,,our ,,nucle> ,,future 444 ,,facts ,,dang]s ,,& ,,opportunities ,,by ,edw>d ,tell] ,,& ,alb]t ,l4 ,latt] ,,crit]ion ,,books ,,new ,,york ,copyright #aieh1 by ,crit]ion ,books1 ,inc4 ,libr>y ( ,congress ,catalog ,c>d ,numb] #eh-hghc ,design$ by ,sidney ,fe9b]g ,,manufactur$ ,,9 ,,! ,,unit$ ,,/ates ,,( ,,am]ica ,,by ,,am]ican ,,book-,,/rat=d ,,press1 ,,inc41 ,,new ,,york ,preface ,?is book has be5 writt5 = ! layman :o has no k ab\t atoms1 bombs & radioactivity4 ,he kn[s t ! _w is made ( atoms1 t bombs might de/roy x & t radioactivity c\ld make x a place mu* less agreeable to live 94 ,we %\ld l to give "s advice ab\t ! use ( ! book3 ,ea* *apt] c be read by itself4 ,! *apt]s ne$ n be tak5 9 ! ord] 9 :i* !y are pr9t$4 ,to read !m all w give a m complete und]/&+--& if y h "t x is be/ to read !m 9 ! ord] !y are arrang$4 ,"s ( ! e>li] *apt]s p]haps ov]fl[ ) facts4 ,9 "s lat] *apt]s we wi% t m facts 7 available4 ,^! latt] ! read] w probably und]/& & rememb] q easily4 ,he may n agree ) all ( _! cont5ts4 ,on ! o!r h& ! m sci5tific *apt]s 7,,ii to ,,viii7 w n be que/ion$ b may be h>d] to read & to rememb]4 ,x w be a help to keep ?is 9 m9d3 ,no *apt] foll[s f ano!r b mo/ *apt]s are relat$ & support "s o!r "p ( ! book4 ,our k ab\t fall\t is increas+ rapidly4 ,"s que/ions :i* are rais$ 9 ! book may already h be5 answ]$4 ,) ?is add$ k we might h be5 m quantitative 9 "s ( our /atem5ts4 ,b we believe ! ma9 conclusions w\ld n be alt]$4 ,?is book 0 complet$ be=e ! ,sputniks4 ,9 _! pres5t =m ^! h little to d ) ! subject ( nucle> en]gy4 ,h[ev]1 to our m9d1 ! urg5cy has become great] = ! non-sci5ti/ to und]/& ^? p>ts ( sci5ce & te*nology :i* may affect 8 safety & well-be+1 & ! safety & well-be+ ( 8 c\ntry4 ,we hope t ?is book w contribute 9 "s measure to su* und]/&+4 ,cont5ts ,preface #e ,i4 ,! ,ne$ to ,"k #ac ,,ii4 ,atoms #ah ,,iii4 ,nuclei #bf ,,iv4 ,! ,law ( ,radioactive ,decay #cg ,v4 ,breakup ( ! ,nucleus #da ,,vi4 ,reactions ,betwe5 ,nuclei #di ,,vii4 ,fission & ! ,*a9 ,reaction #eh ,,viii4 ,action ( ,radiation on ,matt] #fh ,,ix4 ,! ,te/ #hj ,x4 ,! ,radioactive ,cl\d #hg ,,xi4 ,f ! ,soil to ,man #ajd ,,xii4 ,dang] to ! ,individual #aaf ,,xiii4 ,dang] to ! ,race #abg ,,xiv4 ,! ,cobalt ,bomb #acd ,,xv4 ,:at ,ab\t ,future ,te/s8 #acg ,,xvi4 ,has ,some?+ ,happ5$ to ! ,wea!r8 #adf ,,xvii4 ,safety ( ,nucle> ,reactors #aeb ,,xviii4 ,by-products ( ,nucle> ,reactors #afj ,,xix4 ,! ,nucle> ,age #afh ,gloss>y #age ,li/ ( ,illu/rations ,a section ( photographs w be f\nd betwe5 pages #if & #ig4 #a4 ,a %all[ und]gr\nd explosion4 #b4 ,an atomic te/ t[]4 #c4 ,a t[] %ot4 #d4 ,an air %ot4 #e4 ,leg bone ( a rabbit aft] injection ( ,sr4 #f4 ,leg bone ( a woman dead ( radium poison+4 #g4 ,capsules ( cobalt4 #h4 ,cobalt irradiation4 #i4 ,smoke-r+ cl\d f ! air-def5se atomic weapon4 #aj4 ,wilful exposure--an exp]im5t4 #aa4 ,cond5sation trails produc$ 9 a ,wilson ,cl\d ,*amb]4 #ab4 ,closely-spac$ tracks =m a cl\d4 #ac4 ,cutaway section ( a nucle> reactor4 ,,our ,,nucle> ,,future ,,*apt] ,i ,! ,ne$ to ,"k ,our _w is *ang+1 & ! *ange is becom+ m rapid4 ,! mov+ =ce beh9d ?is *ange is sci5tific discov]y4 ,all ( u are deeply affect$ by ! consequ5ces ( sci5ce4 ,at ! same "t1 v few und]/& ! highly te*nical f\ndations ( our civilization4 ,9 ?is situation x is natural t sci5tific & te*nical progress %\ld create uneas9ess & al>m4 ,fe> ( :at we d n "k or d n und]/& has be5 ) u 9 all ages4 ,man1 kn[+ t 8 life w end1 has (t5 be5 prey to an ev5 m t]rible nightm>e--! end ( 8 :ole _w4 ,9 a sci5tific age mo/ ( ! pa/ t]rors h turn$ out to be s5seless *im]as4 ,b "o m5ace rema9s4 ,x is ! great & p]man5t unkn[n3 :at w we humans d to ea* o!r & to ourselves8 ,! worry ab\t our own actions w cont9ue4 ,x may gr[ z our p[] ov] nature increases4 ,aga9/ ?is worry !re exi/ two weapons3 und]/&+ & c\rage4 ,( ! two1 c\rage is m important b und]/&+ mu/ come fir/4 ,we are frequ5tly al>m$ by imag9>y dang]s1 :ile disreg>d+ risks :i* are mu* m real4 ,!re %\ld exi/ a close int]action betwe5 public op9ion on ! "o h& & te*nical progress on ! o!r4 ,= ?is end an und]/&+ ( mod]n sci5tific developm5ts is requir$4 ,!re is an increas+ly urg5t ne$ to "k4 ,little is done to satisfy ?is ne$4 ,! op9ion has ga9$ gr\nd t ?is ne$ c 9 fact n be satisfi$4 ,at ! same "t1 m & m p believe t ! sci5ti/s & te*nical p !mselves are responsible = ! *anges :i* _! ideas & inv5tions h br\ght ab\t4 ,! sci5ti/ is put 9 ! position :]e 8 voice is he>d1 n only 9 ! highly specializ$ fields 9 :i* he is an exp]t1 b also 9 ! mu* m g5]al matt]s :i* are affect$ by 8 discov]ies4 ,! real s\rce ( important decisions 9 our c\ntry is ! p4 ,we believe t ?is is rightly s1 & we believe t x is n prop] if sci5ti/s take ov] any ess5tial "p ( ^! decisions4 ,! responsibility ( a te*nical man c]ta9ly includes two important functions4 ,"o is to explore nature & to f9d out ! possible limits ( our p[] ov] nature4 ,! o!r is to expla9 :at he has f\nd 9 cle>1 simple1 & /raight=w>d t]ms1 s t ess5tial decisions c be made by all ! p ( our c\ntry--to :om ! p[] ( decision prop]ly belongs1 & :om ! consequ5ces ( ^! decisions w ultimately affect4 ,to expla9 sci5tific & te*nical matt]s is n easy1 & to become famili> ) all sci5ce might actually be impossible4 ,9 ! specializ$ field ( physics !re h be5 revolution>y developm5ts 9 ! tw5tie? c5tury l ! !ory ( relativity discov]$ by ,e9/e9 & ! !ory ( ! atom orig9at$ by ,niels ,bohr4 ,^! new discov]ies are n easy to und]/&1 & e good physici/ has sp5t ye>s ( 8 life try+ to get ?or\ghly acqua9t$ ) _! mean+4 ,all ( u :o h done s feel t we are well rew>d$ by ! bett] und]/&+ ( nature :i* we h acquir$4 ,b x is n necess>y to talk ( ^! matt]s "h4 ,:at we h to discuss 9 ?is book is connect$ ) p>ts ( atomic & nucle> physics :i* are mu* m elem5t>y4 ,! facts :i* we %all pres5t 9 a simple fa%ion are suffici5t to give ! read] an ori5tation 9 ! seem+ly bewild]+ fields ( nucle> en]gy & atomic explosions4 ,we %all h to />t by describ+ atoms & nuclei4 ,^! are r small objects1 b ?is circum/ance ne$ n p>ticul>ly bo!r u2 & x is n necess>y to fright5 ourselves ) ! idea t we are talk+ ab\t 8unimag9ably0 small objects4 ,our m9ds adapt !mselves q readily to new dim5sions2 & :ile we are talk+ ab\t nuclei1 we c tempor>ily =get t any bigg] objects exi/4 ,real difficulties arise only :5 sci5ce discov]s laws :i* seem to contradict common s5se4 ,?is does n happ5 frequ5tly1 & we %all n ne$ to dwell ^u su* subjects4 ,! difficulties ( expla9+ sci5ce are increas$ by ! fact t sci5ti/s h develop$ a language ( _! own :i* !y practice & p]fect by talk+ to ea* o!r4 ,"o sometimes has ! impression t !y talk to ea* o!r exclusively4 ,! au?ors feel t _! own 8native tongue0 is ?is sci5tific language2 ?is book is an ef=t at a translation4 ,a fur!r difficulty is connect$ ) ! special subject3 radioactivity4 ,! great practical importance ( ?is subject has dawn$ ^u ! public 9 connection ) ! explosion at ,hiro%ima4 ,?is 0 a fright5+ occasion1 & ! subsequ5t developm5ts & prospects are no less fright5+4 ,x is n necess>y t ev]y?+ connect$ ) nucle> explosions %\ld be equally fright5+2 & x is important t we %\ld approa* ! subject ) an op5 m9d & ) z few emotions z is humanly possible4 ,! emotions h _! necess>y place :5 we get to ! /age 9 :i* we want to decide our actions4 ,we sugge/ to ! read] t he %\ld delay ?is /age until ! "t :5 he has f9i%$ read+ ! book4 ,! greate/ difficulty 9 discuss+ ! radiation haz>ds arises because ! work+ ( liv+ organisms is involv$4 ,basically1 we are 9 ! d>k ab\t ! "q h[ su* an organism works4 ,we are equally 9 ! d>k ab\t ! "q h[ su* an organism is affect$ by radiation4 ,x w\ld !re=e seem t we mu/ rema9 9 d\bt :e!r or n radioactivity is dang]\s1 except = ^? cases :]e obvi\s damage has be5 done4 ,s9ce ! imm$iate effects ( radioactivity are n p]ceiv$ by our s5ses1 we are fac$ ) ! ?\ght ( an invisible m5ace ( unkn[n ext5t4 ,"s ( ! h>mful consequ5ces may %[ up ye>s lat]1 & !re=e ev5 ! abs5ce ( any obs]v$ damage w n reassure p4 ,=tunately1 our practical k is by no means z defici5t z ^! /atem5ts w\ld sugge/4 ,radioactivity1 & processes simil> to radioactivity1 surr\nd u & h surr\nd$ our ance/ors = z long z life has exi/$ on e>?4 ,we d n "k :at life is1 & we d n "k 9 :at detail$ mann] life is affect$ by radioactivity2 b we h broadly bas$ & c]ta9 k t artificial radioactivity w produce simil> effects to ^? produc$ by ! natural backgr\nd ( radioactivity4 ,?is backgr\nd1 !re=e1 provides u ) a y>d/ick to :i* all man-made contam9ations c be comp>$4 ,!re is a f9al ob/acle to ! explanation ( matt]s connect$ ) radioactivity4 ,?is is ! secrecy :i* has be5 associat$ ) ! developm5t ( nucle> en]gy1 & 9 p>ticul> ) ! milit>y applications ( nucle> en]gy4 ,! argum5ts = keep+ in=mation conc]n+ weapons secret are /rong1 prop]1 & g5]ally und]/ood4 ,!re is1 h[ev]1 no su* /rong argum5t1 & 9 fact no possibility = secrecy connect$ ) ! widely disp]s$ radioactivity :i* orig9ates f ! weapons4 ,9 recognition ( ?is fact1 secrecy has be5 completely & prop]ly remov$ f ?is field4 ,x is n surpris+ t x took "s "t to d s4 ,adm9i/rative decisions h be5 involv$1 & ^! are nev] tak5 9 a v great hurry4 ,ev5 ?\gh _w-wide radioactive contam9ation has be5 s9ce #aiee op5 to g5]al sci5tific discussion1 ! "t does n seem to h be5 suffici5t to insure a wide dissem9ation & explanation ( ! results4 ,!re may also rema9 "s l+]+ d\bts :e!r all relevant in=mation has be5 made available4 ,9 actual fact1 ! sci5tific in=mation on ?is important topic is completely & freely available at ! pres5t "t4 ,in=mation conc]n+ ! peaceful applications ( nucle> en]gy is also completely & freely available4 ,ev5 9 ! field ( milit>y applications1 mu* ( ! ess5tial in=mation has be5 publi%$4 ,we are !re=e 9 a position to put be=e ! read] ! mo/ important facts ab\t ! peaceful & milit>y applications ( nucle> en]gy--( ! possible dang]s & ( ! ev5tual b5efits4 ,if we d n succe$1 we _c blame ei!r secrecy or ! difficulty ( ! subject4 ,x is true t ! subject is involv$1 b only 9 ! same way z are ^? subjects ( ev]yday exp]i5ce ) :i* all ( u h to /ruggle once 9 a :ile4 ,no great] intellectual ef=t is ne$$ ?an is involv$ 9 ! und]/&+ ( ! income tax =m or ! rac+ =m1 to m5tion two analogies ( r div]se emotional cont5t4 ,_m ( ! ideas w be unfamili>1 b !y are n complex4 ,fur!rmore1 _! be>+ on our safety1 well-be+1 & ! possible improvem5t ( our lives is great4 ,!re=e we hope t ! read] w give z mu* ( 8 att5tion to ?is matt] z he is accu/om$ to devote to o!r subjects :i* are connect$ ) 8 necessities or 8 amusem5t4 ,,*apt] ,,ii ,atoms ,all matt] is compos$ ( atoms1 :i* are v t9y objects4 ,we _c see !m because waves ( light wa% ov] !m l ocean waves ov] a pebble4 ,an atom is ab\t z big 9 comp>ison to a human cell1 :i* c be cle>ly se5 "u an ord9>y microscope1 z a human cell is 9 comp>ison to a billi>d ball4 ,some:at m precisely1 a hundr$ million atoms laid side by side w\ld be ab\t an in* 9 l5g?4 ,despite its ,greek "n1 :i* means indivisible1 ! atom is made up ( p>ts4 ,x consi/s ( a c5tral nucleus1 :i* c>ries a positive electrical *>ge1 ar\nd :i* "o or m negatively *>g$ electrons are di/ribut$4 ,"o frequ5tly he>s ( ! electrons revolv+ 9 orbits ar\nd ! nucleus1 some:at z ! planets revolve ar\nd ! sun 9 our own sol> sy/em4 ,?is is n q a correct picture1 h[ev]4 ,= "o ?+ ! electrons are m elusive ?an ! planets4 ,!y d n revolve 9 def9ite orbits z ! planets d4 ,also ! orbits are m delicate4 ,"o w\ld de/roy ! atom by ! attempt to f9d out precisely :at ! electron orbits are4 ,illu/ration3 ,?is is h[ an atom does n look4 ,! electrons d n move along well-def9$ pa?s4 ,x is m difficult to convey ! idea ( an atom by a picture ?an x is to make a draw+ ( la/ night's dream4 ,! planets d n fly away f ! sun because ( ! gravitational attraction :i* ! sun ex]ts4 ,! electrons & ! nucleus1 h[ev]1 are held toge!r because positive & negative electrical *>ges attract ea* o!r4 ,! gravitational attraction betwe5 ! electrons & ! nucleus is incr$ibly weak comp>$ to ! electrical attraction4 ,mo/ ( ! atom's weight comes f its nucleus4 ,ev5 ! lighte/ kn[n nucleus weighs ab\t #ahdj times z mu* z an electron4 ,9 spite ( ?is1 ! nucleus occupies only a t9y portion ( ! total volume ( ! atom4 ,9 fact1 ! nucleus is ab\t z big 9 comp>ison to ! :ole atom z ! atom is 9 comp>ison to ! human cell4 ,tw5ty ?\s& nuclei laid side by side w\ld be ab\t equal 9 l5g? to ! diamet] ( ! atom4 ,if matt] 7 compos$ ( no?+ b nuclei d5sely pack$ toge!r1 an object ! size ( a p5ny w\ld weigh approximately =ty million tons4 ,lat] we are go+ to see t ! size ( ! nucleus has a great effect ^u ! ways 9 :i* nuclei react ) ea* o!r4 ,= t v reason ! size ( ! nucleus is a well-def9$ measurable quantity4 ,x is mu* h>d] to say precisely :at "o means by ! size ( ! electron4 ,x seems acceptable to say t x is some:at less ?an ! size ( ! av]age nucleus4 ,9 any case x is c]ta9 t bo? ! electrons & ! nucleus are small comp>$ to ! size ( ! :ole atom4 ,consequ5tly1 ! atom mu/ consi/ mo/ly ( empty space4 ,?is means1 ( c\rse1 t :5 y look at solid matt]1 :at is be=e y\r eyes is empty space ) a slight addition ( real sub/ance4 ,:at l5ds /r5g? to solids is ! int]play ( electric attractions & repulsions inside atoms & betwe5 atoms4 ,:5 a *>g$ p>ticle1 su* z an electron or a nucleus1 happ5s to move ?r\gh solid matt]1 x is con/antly act$ on by l>ge electric =ces4 ,to su* a p>ticle matt] does n seem to be v transp>5t4 ,b if !re 7 su* a ?+ z an electrically neutral p>ticle1 comp>able 9 size to ! nucleus1 x w\ld be able to move ar\nd freely inside matt]1 )\t exp]i5c+ electric =ces1 & only n[ & aga9 bump+ into a nucleus or maybe an electron4 ,z a matt] ( fact1 !re is su* a p>ticle & x c pass "r ?r\gh an in* or two ( solid matt] )\t bump+ into any?+4 ,lat] on 9 ?is book we %all be v int]e/$ 9 ?is p>ticle1 :i* is call$ a neutron4 ,al?\gh ! electrons & ! nucleus are *>g$ p>ticles1 ! atom z a :ole is electrically neutral2 ?is means t ! positive *>ge ( ! nucleus mu/ be equal 9 magnitude to ! total *>ge ( all ! negative electrons4 ,all electrons h precisely ! same *>ge1 :i* is ! smalle/ *>ge t has ev] be5 obs]v$4 ,:at is p>ticul>ly /range & n yet expla9$ is ! fact t all o!r *>ges are z big z ! electron *>ge1 or twice z big1 or ?ree times z big1 or a million times z big4 ,b we nev] f9d a *>ge :i*1 express$ 9 t]ms ( ! electron *>ge1 is fractional4 ,no object ev] c>ries ?ree & a half electron *>ges4 ,! electron *>ge !re=e may be us$ conv5i5tly z a /&>d unit ( *>ge4 ,e atom c be di/+ui%$ by ! *>ge ( its nucleus4 ,! simple/ atom "o c imag9e w\ld cle>ly be "o ) a s+le electron revolv+ ar\nd a nucleus hav+ "o unit ( positive *>ge4 ,su* an atom exi/s & is call$ hydrog54 ,an atom ) a nucleus ( *>ge two & two electrons revolv+ ar\nd x1 is call$ helium2 ?ree1 li?ium 444 six1 sev51 eight2 c>bon1 nitrog51 oxyg5 444 #ib1 uranium4 ,atoms ) almo/ all *>ges f "o to #ib are f\nd 9 nature1 & practically none above #ib are f\nd4 ,"s odd *>ges--#dc1 #fa1 #he1 & #hg--;are miss+4 ,! reason = ^! miss+ atoms is connect$ ) ! prop]ties ( ! nucleus4 ,! nucleus w soon become our ma9 object ( int]e/4 ,! mo/ surpris+ fact ab\t atoms is _! simil>ity1 inde$ _! id5tical behavior4 ,if two atoms h ! same k9d ( nucleus & h ! same numb] ( electrons revolv+ ar\nd ^! nuclei1 !n ^! two atoms are apt to be enc\nt]$ 9 a condition :i* is mo/ precisely ! same = ! two4 ,"o c\ld imag9e t ! v>i\s compon5t p>ts ( ! atom w\ld be arrang$ 9 diff]5t ways & f\nd 9 diff]5t /ates ( motion1 9 a v>iety )\t limit4 ,:5ce ! complete simil>ity8 ,! answ] to ?is "q is n only mo/ surpris+1 b x is ev5 9 app>5t contradiction to common s5se4 ,= ?is v reason x is difficult to expla94 ,! h>de/ ?+s to und]/& are n ^? :i* are complicat$ b ^? :i* are unexpect$4 ,=tunately = our purpose we ne$ n g into ?is m intricate portion ( atomic physics4 ,x is suffici5t to say t !re is "o arrangem5t or patt]n ( motion ( ! electrons :i* is pref]r$ & :i* leads to ! greate/ /ability ( ! atom4 ,if ! electrons are 9 ?is p>ticul> /ate ( motion1 :i* is call$ ! gr\nd /ate1 !y h less en]gy ?an !y w\ld h if !y 7 9 any o!r /ate ( motion4 ,!re are o!r less /able1 b n less %>ply def9$1 /ates ( atoms :i* we call 8excit$0 /ates4 ,:5 an atom is 9 su* an excit$ /ate1 x t5ds to be un/able & tries to get into ! gr\nd /ate z soon z possible4 ,s9ce ! gr\nd /ate conta9s less en]gy ?an any o!r /ate1 ! atom mu/ release en]gy 9 ! process ( adju/m5t4 ,! releas$ en]gy manife/s itself 9 ! =m ( electromagnetic radiation--(t5 z a little pulse ( visible light4 ,! color ( ?is light dep5ds ^u ! am\nt ( en]gy releas$1 go+ progressively ?r\gh ! ra9b[ f r$ t[>d blue z ! am\nt ( en]gy increases4 ,!re are v few /ates 9 :i* ! excitation en]gy is small4 ,b ( /rongly excit$ /ates !re is a great abundance4 ,9 ! region ( ?is high excitation small additional *anges are possible4 ,?us we approa* a situation m 9 accordance ) exp]i5ce & common s5se3 ! patt]n ( motion c be *ang$ by any small am\nt4 ,! description we h j giv5 is ( c\rse incomplete4 ,we mu/ avoid "h ! crucial que/ions :y only "s patt]ns ( motion are possible1 :y "o l[e/ level is /able & :y ! electrons nev] desc5d into decreas+ /ates ( en]gy1 foll[+ ! attraction ( ! nucleus4 ,at ! same "t "o %\ld emphasize t a complete explanation ( ^! facts has be5 giv54 ,?is explanation makes precise pr$ictions ab\t _m ( ! prop]ties ( matt]1 & we c h complete confid5ce t1 b = ! involv$ ma!matical proc$ure1 all ord9>y prop]ties ( mat]ials c\ld be precisely pr$ict$4 ,! atom has be5 expla9$ z completely z ,newton has expla9$ ! motion ( planets4 ,to =m an idea :at an atom is or :y two atoms (1 let u say1 hydrog5 are precisely ! same1 x is n necess>y to se>* = intricate reasons or deep mean+s4 ,two atoms ( ! same k9d are alike z two pawns are = ! *ess play]1 except = "o little po9t3 9 ! case ( ! pawns we d n c>e ab\t ! diff]5ce2 9 ! case ( ! atoms !re is no diff]5ce4 ,?is is a simple /atem5t & x hone/ly describes a simple situation4 ,! beauty ( sci5ce is due to ! fact t ! correct answ]s to our mo/ int]e/+ que/ions h turn$ out to be surpris+ by _! simplicity4 ,9 ord] to und]/& an atom "o mu/ consid] ! di/ribution ( electrons ar\nd "o nucleus4 ,9 ord] to und]/& a molecule "o has to consid] ! di/ribution ( electrons ar\nd two or m nuclei4 ,! *emical behavior ( an atom is ! mann] 9 :i* x int]acts ) o!r atoms1 & t means ! precise way 9 :i* ! electrons re>range !mselves :5 two or m atoms approa* ea* o!r4 ,! int]action betwe5 atoms occurs ma9ly betwe5 _! out]mo/ electrons4 ,x may happ5 t two q diff]5t atoms1 conta9+ nuclei ( diff]5t *>ges & diff]5t numb]s ( electrons1 may nev]!less be simil> 9 ! /ructure ( _! out]mo/ electrons4 ,9 ?is case ! two atoms exhibit simil> *emical prop]ties4 ,examples are li?ium ) *>ge #c & sodium ) *>ge #aa2 also helium1 *>ge #b & neon1 *>ge #aj4 ,a mo/ important example = our purpose is ! set ( ?ree *emically simil> atoms3 calcium1 *>ge #bj1 /rontium1 *>ge #ch2 & radium1 *>ge #hh4 ,:5 two or m atoms approa* ea* o!r1 :e!r !y are simil> or diff]5t1 _! electrons--p>ticul>ly ! out]mo/ ones--f9d new /ates ( motion in/ead ( ^? t 7 available to !m :5 !re 0 only "o nucleus 9 ! vic9ity4 ,x may n[ happ5 t among/ ^! new /ates ( motion !re are "s t are ev5 m /able ?an ! /ate ( ! sep>at$ atoms4 ,9 ?is ev5t ! atoms w t5d to /ick toge!r1 & ! electrons w adopt :atev] new /ate ( motion n[ corresponds to maximum /ability4 ,! composite sy/em ( ! atoms is call$ a molecule1 & its /ate ( maximum /ability1 ! gr\nd /ate ( ! molecule4 ,!re are atoms ( p>ticul>ly great /ability :i* _c increase _! /ability by comb9+ ) o!r atoms4 ,examples are helium1 neon1 & argon4 ,^! atoms t5d to rema9 s+le1 reta9 _! indep5d5t motion 9 a r 8p]man5t0 gase\s /ate1 & are g5]ally unsociable4 ,!y are call$ !re=e ! noble gases4#a ,an especially simple example ( ! =mation ( a molecule is ! comb9+ ( sodium & *lor9e to =m ord9>y table salt4 ,! sodium atom happ5s to h a r loosely b\nd out] electron4 ,! *lor9e atom possesses a conv5i5t ni*e = an extra electron4 ,consequ5tly ! en]gy sp5t 9 pry+ ! out] electron loose f ! sodium atom is l>gely repaid by add+ x to ! *lor9e atom4 ,! rema9+ sodium 8atom10 depriv$ ( "o ( its electrons1 n[ has a net positive *>ge4#b ,! *lor9e 8atom0 ) its extra electron has a net negative *>ge4 ,! two 8atoms0 !re=e attract ea* o!r to make a molecule ( sodium *loride4 ,actually matt] w cont9ue to aggregate4 ,a great numb] ( positive sodium 8atoms0 & negative *lor9e 8atoms0 w arrange !mselves into a beautiful & regul> lattice :i* is ! sodium *loride cry/al4 ,! simple/ molecule :i* does n t5d to gr[ into a bigg] aggregate is made up ( two hydrog5 atoms4 ,ar\nd two hydrog5 nuclei a p>ticul>ly /able patt]n ( two electrons c be =m$4 ,because ( ?is fact hydrog5 atoms associate pairwise s t ?is patt]n %\ld become possible4 ,! ways 9 :i* atoms c be jo9$ are incr$ibly manifold4 ,!y c =m metals 9 :i* ! out] electrons roam freely & c>ry electric curr5ts ) ! greate/ ( ease4 ,!y c =m liquids 9 :i* atoms or molecules are ti$ toge!r 9 a loose & disord]ly fa%ion4 ,!y c move indep5d5tly mak+ occasional enc\nt]s1 :i* is :at happ5s 9 a gas4 ,& !y c =m long spiral+ molecules :]e gr\ps ( atoms are /rung toge!r )\t an app>5t simple ord]1 b 9 a way :i* is someh[ relat$ to ! processes ( life4 ,illu/ration3 ,arrangem5t ( sodium & *lor9e 8atoms0 9 a cry/al ( common salt4 ,we all "k 9 h[ _m =ms matt] c appe> & h[ *angeable ^! =ms are4 ,t ! /one & ! spray1 ! air & an insect1 & ev5 ! human bra9 %\ld be compos$ ( ! same few k9ds ( atoms1 & t ^! atoms %\ld be subject to laws :i* are subtle & simple & precisely describ$--?is c]ta9ly is ! mo/ rem>kable fact t we h le>n$ s9ce ,newton prov$ t ! same sci5ce applies to ! e>? & 9 ! heav5s4 ,,*apt] ,,iii ,nuclei ,up to n[ we h reg>d$ atoms z be+ divisible into electrons & nuclei4 ,electrons & nuclei1 h[ev]1 we h reg>d$ z indivisible entities4 ,?is po9t ( view is p]fectly adequate to acc\nt = all ! facts ( *emi/ry & mo/ ( ! facts ( physics4 ,ev5 9 physics1 x has n be5 necess>y to ascribe an int]nal /ructure to ! electron4#c ,! electron is a truly elem5t>y p>ticle 9 ?is s5se4 ,h[ev]1 to und]/& "s physical ph5om5a1 & radioactivity is "o ( ^!1 x is necess>y to recognize t ! nucleus is n indivisible b consi/s ( p>ts4 ,! p>ts ( ! nucleus are call$ protons & neutrons4 ,! simple /atem5ts ( ! previ\s *apt] apply to ^! small] p>ticles also4 ,all electrons are equal--precisely equal4 ,all protons are equal & all neutrons are equal4 ,!re are me?ods :i* w\ld h %[n up exce$+ly small diff]5ces betwe5 ^! p>ticles4 ,no su* diff]5ces h be5 discov]$4 ,z f> z we "k ^! p>ticles are always ! same4 ,we _c p\r en]gy into !m & excite !m z 0 ! case ) ! atoms4 ,:5 we come to consid] ^! small p>ticles1 ! complex /ructure ( ! _w has an end4 ,in/ead :at we f9d is simple4 ,a proton & a neutron h almo/ exactly ! same weight4 ,! proton has "o unit ( positive *>ge1 :i* means t its *>ge is ! same z t ( ! electron except t x is opposite 9 sign4 ,! neutron1 z its "n implies1 is an electrically neutral p>ticle4 ,h5ce ! *>ge ( ! nucleus is equal to ! numb] ( protons x conta9s1 & is indep5d5t ( ! numb] ( neutrons4 ,! weight ( ! nucleus1 h[ev]1 tak+ ! proton 7or ! neutron7 z a unit ( weight1 is equal to ! numb] ( protons plus ! numb] ( neutrons4 ,imag9e t we h two atoms ^: nuclei h ! same numb] ( protons b a diff]5t numb] ( neutrons4 ,su* atoms exi/ 9 nature & are call$ isotopes4 ,! po9t ab\t ^! isotopes is t s9ce !y h ! same numb] ( protons1 !y h ! same nucle> *>ge1 ! same electron /ructures1 & h5ce !y h almo/ ! same *emical prop]ties4 ,_! nuclei h some:at diff]5t volumes4 ,b ! nucleus is small 9 any case4 ,x is almo/ z ?\gh we tri$ to look = ! diff]5ce betwe5 no?+ & twice-no?+4 ,! diff]5ce 9 ! weights ( isotopes due to ! diff]5ce 9 _! numb]s ( neutrons1 has only a negligible influ5ce on _! *emical behavior4 ,an important consequ5ce ( ?is fact is t molecules :i* diff] only 9 t "o isotope has be5 sub/itut$ = ano!r are biologically indi/+ui%able4 ,!y ta/e ! same & smell ! same4 ,!y are +e/$ 9 our bodies 9 ! same way1 & !y are deposit$ or excret$ 9 ! same way4 ,! simple/ isotopes are ! isotopes ( hydrog54 ,mo/ ( ! hydrog5 atoms we f9d 9 nature h a nucleus :i* is a s+le proton4 ,?is is ! common hydrog5 or light hydrog54 ,a few hydrog5 atoms1 h[ev]1 h nuclei :i* consi/ ( a proton & a neutron4 ,?is is ! heavy hydrog51 f\nd 9 heavy wat]4 ,9 all natural s\rces ( wat] ^! two k9ds ( hydrog5 are mix$ 9 a ratio :i* is practically ! same = e sample4 ,! electron circulat+ ar\nd ! nucleus behaves almo/ exactly ! same way :e!r ! extra neutron is pres5t or n4 ,on ! /ate ( t electron dep5d mo/ prop]ties ( ! atom & ! molecules :i* conta9 x4 ,( c\rse1 heavy hydrog5 has twice ! weight ( common hydrog51 & heavy wat] is some:at m d5se ?an light wat]4 ,b o!rwise !re is little diff]5ce4 ,! /ory ( ! discov]y ( ! hydrog5 isotopes is amus+4 ,ab\t half a c5tury ago--be=e ! discov]y ( any isotope--two sci5ti/s tri$ to measure ! d5sity ( wat]4 ,!y purifi$ ! wat] by boil+ x & cond5s+ ! vapor4 ,b ! m !y purifi$1 ! light] x became--slightly b p]ceptibly4 ,f9ally !y gave up3 wat] seem$ to h no d5sity6 ,:at really happ5$ 0 ?is3 ,light wat] boils a little bit m easily ?an heavy wat]4 ,)\t realiz+ x1 ^! sci5ti/s _h />t$ to sep>ate isotopes4 ,_m ye>s lat] ,h>old ,urey--on ! basis ( "s mi/ak5 exp]im5ts ( o!r p--conclud$ t heavy hydrog5 mu/ exi/4 ,he look$ = x & f\nd x1 b f\nd mu* less ?an he _h expect$4 ,!re 0 s little heavy hydrog5 t on ! basis ( correct exp]im5ts ,urey nev] w\ld h guess$ its pres5ce4 ,x seems t an unf\nd$ idea is mu* m fruitful ?an ! abs5ce ( an idea4 ,almo/ all naturally occurr+ elem5ts are f\nd to consi/ ( m ?an "o isotope4 ,uranium1 = example1 is compos$ ma9ly ( two1 "o hav+ #adc neutrons & ! o!r hav+ #adf4 ,s9ce bo? ( ^! isotopes h #ib protons1 _! weights are #ib #adc #bce & #ib #adf #bch respectively4 ,x is cu/om>y to ref] to ^! isotopes z ,u & ,u4 ,! ,u1 :i* is valuable 9 atomic reactors & 9 ! manufacture ( atomic bombs1 is comp>atively r>e1 occurr+ z only "o "p 9 #adj ( natural uranium4 ,! sep>ation ( ?is r>e isotope f ! common #bch 0 "o ( ! major und]tak+s ( ! two billion doll> ,manhattan ,project dur+ ,_w ,w> ,,ii4 ,we come n[ to a mo/ important "q1 "o t w lead u to ! idea ( radioactivity3 ,:at is x t det]m9es :i* isotopes a giv5 elem5t w h8 ,= example1 uranium has isotopes weigh+ #bce & #bch4 ,small am\nts ( ,u & ,u are also f\nd 9 nature4 ,:y d we n f9d ,u1 ,u1 ,u or ,u8 ,evid5tly only c]ta9 numb]s ( neutrons w hang toge!r ) #ib protons4 ,consid] ano!r example1 ?is "t ( ! lighte/ kn[n elem5t1 hydrog54 ,we h already m5tion$ two isotopes ( hydrog53 light hydrog5 ) weight #a 7symboliz$ ,h71 hav+ a nucleus consi/+ ( a s+le proton & no neutrons1 & heavy hydrog5 7also call$ deut]ium7 ( weight #b 7,h71 hav+ "o proton & "o neutron4 ,! latt] isotope occurs z only ab\t "o "p 9 #e1jjj ( natural hydrog54 ,!re is also a slight trace ( tritium 7,h71 hav+ "o proton & two neutrons4 ,b "h ! sequ5ce /ops4 ,:at has happ5$ to ,h1 ,h1 ,h1 etc8 ,?is "q is relat$ to ! e>li] "o3 :y !re are no atoms 9 nature ( *>ge #dc1 #fa1 #he1 & #hg1 & :y !re are none ) *>ges great] ?an #ib4 ,to answ] ^! que/ions requires a little k ab\t ! laws :i* gov]n ! motion ( neutrons & protons )9 ! nucleus1 & ! nature ( ! =ces :i* are ex]t$ by a neutron on a neutron1 a neutron on a proton1 & a proton on a proton4 ,! motion ( neutrons & protons )9 ! nucleus is gov]n$ by ! same laws :i* gov]n ! motion ( electrons )9 ! atom4 ,= bo? ! nucleus & ! atom !re is a gr\nd /ate ( motion :i* has m /ability 7less en]gy7 ?an any o!r /ate4 ,( c\rse ! arrangem5t & motion ( electrons 9 ! atom dep5d n only on ?is g5]al rule b also on ! specifically electrical nature ( ! =ces :i* act betwe5 ! electrons & ! nucleus4 ,9 ! same way ! arrangem5t & motion ( ! neutrons & protons )9 ! nucleus dep5d ^u ! nature ( ! =ces :i* act betwe5 neutrons & protons4 ,^! =ces are def9itely n ( gravitational orig94 ,gravitational attraction is extremely weak comp>$ to ! attraction betwe5 neutrons & protons1 & is utt]ly negligible 9 ! realm ( nucle> ph5om5a4 ,nei!r c ! nucle> =ces be electrical 9 orig94 ,! neutrons are electrically neutral2 & ! protons actually repel ea* o!r by virtue ( _! electrical *>ge4 ,! nucle> =ces are some?+ entirely new4 ,!y are ! /ronge/ =ces yet enc\nt]$1 & !y are )\t a c\nt]p>t 9 ! macroscopic _w4 ,nucle> =ces are n yet completely und]/ood4 ,b to und]/& nucle> /ability we ne$ to "k only "o peculi> fact gov]n+ ! behavior ( neutrons & protons 7& incid5tally also electrons73 ,!y want to be diff]5t4 ,to ea* p>ticle a /ate or patt]n ( motion c be assign$4 ,:5 any two neutrons are comp>$1 _! patt]n ( motion mu/ be ess5tially diff]5t4 ,! same holds = any two protons4 ,a neutron & a proton1 h[ev]1 may be f\nd 9 simil> patt]ns s9ce !y diff] anyway 9 _! *>ge4 ,n[ among ! possible patt]ns ( motion "s h l[] & "s h high] en]gies4 ,individual neutrons & protons w fir/ occupy ! l[e/ en]gy /ates1 9 accordance ) ! rule ( lea/ en]gy = maximum /ability4 ,!n ! dem& = a diff]5ce w =ce subsequ5t p>ticles into patt]ns ( high] & high] en]gies4 ,s9ce a neutron does n exclude a proton f be+ 9 ! same patt]n1 ! l[e/ en]gy /ate may be occupi$ simultane\sly by "o neutron & "o proton4#d ,if ano!r neutron or proton is add$1 x mu/ be put into ! next /ate ( high] en]gy4 ,= ?is reason we w\ld expect t nuclei are mo/ /able :5 !y conta9 an equal or ne>ly equal numb] ( neutrons & protons4 ,= nuclei :i* are n too heavy1 ?is is inde$ ! case4 ,= example1 nitrog51 :i* has sev5 protons1 has two /able isotopes1 ,n & ,n1 ) sev5 & eight neutrons respectively4 ,= heavy nuclei1 h[ev]1 ! situation is a little diff]5t4 ,! nucle> =ce betwe5 neutrons & protons acts only ov] a v %ort range--! p>ticles mu/ almo/ be 9 contact ) ea* o!r 9 ord] to exp]i5ce a sizeable attraction4 ,consequ5tly a neutron or a proton int]acts only ) its imm$iate neighbors 9 ! nucleus4 ,! electrical repulsion betwe5 ! protons1 h[ev]1 acts ov] a mu* long] range4 ,a proton is repell$ by all ! o!r protons 9 ! nucleus4 ,= heavy nuclei ?is repulsion is suffici5t to r$uce ! numb] ( protons relative to ! numb] ( neutrons4 ,lead1 = example1 ) #hb protons1 has f\r /able isotopes1 ) #abb1 #abd1 #abe1 & #abf neutrons4 ,we h said t sev5 protons w comb9e /ably ) sev5 or eight neutrons4 ,:at happ5s if sev5 protons are comb9$ ) six or n9e neutrons 7to make ,n or ,n78 ,our rule does n prev5t !m f /ick+ toge!r2 x says only t ^! comb9ations w\ld be m /able if a proton c\ld be conv]t$ into a neutron 79 ! case ( six7 or a neutron into a proton 79 ! case ( n9e74 ,actually sev5 protons & n9e neutrons d /ick toge!r1 b su* a nucleus is n /able & does n cont9ue to exi/ indef9itely4 ,! reason is q simple & a little surpris+3 ,! conv]sion ( a neutron into a proton is actually a physically realizable process1 & fur!rmore x releases "s en]gy4 ,simil>ly a nucleus conta9+ sev5 protons & six neutrons w h an exi/5ce ( only f9ite duration because ! conv]sion ( a proton into a neutron c also occur4 ,( c\rse ! proton is *>g$ & ! neutron is n4 ,:at happ5s to ! *>ge dur+ ^! trans=mations8 ,actually ! neutron is trans=m$1 n into a proton1 b into a proton plus an electron4 ,! proton is trans=m$ likewise into a neutron plus some?+ else4 ,?is some?+ else is call$ a positron & is id5tical ) ! electron 9 e respect except 9 hav+ a positive in/ead ( a negative *>ge4 ,! *anges j describ$ occur spontane\sly4 ,!y are examples ( radioactivity4 ,m specifically !y are call$ 8beta decay0 processes because an electron 7or a positron7 :5 emitt$ by a nucleus is call$ a beta ray4 ,su* beta-radioactive sub/ances are produc$ :5ev] nucle> en]gy is us$ 9 an explosion or 9 a p[] plant4 ,_m ( ! difficulties & worries conc]n+ nucle> en]gy are connect$ ) ^! beta activities4 ,we %all be conc]n$ ) !m (t5 z h>mful1 sometimes z helpful ag5ts4 ,:5 a neutron is conv]t$ into a proton & an electron inside a nucleus1 ! electron escapes imm$iately1 b ! proton rema9s 9 ! nucleus4 ,simil>ly1 :5 a proton is conv]t$ into a neutron & a positron1 ! positron escapes & ! neutron rema9s 9 ! nucleus4 ,s9ce ! electron & ! positron h a negligible weight comp>$ to a proton or a neutron1 ! process ( beta decay leaves ! weight ( ! nucleus ne>ly un*ang$4 ,s9ce ! electron & ! positron are *>g$1 ! process ( beta decay increases or decreases ! *>ge ( ! nucleus by "o unit4 ,aft] beta decay a nitrog5 nucleus ) sev5 protons & six neutrons 7,n7 becomes a nucleus ) six protons & sev5 neutrons--c>bon ) weight #ac 7,c71 :i* is a /able comb9ation4 ,simil>ly a nitrog5 nucleus ) sev5 protons & n9e neutrons 7,n7 becomes a nucleus ) eight protons & eight neutrons1 oxyg5 ) weight #af 7,o71 :i* is ord9>y /able oxyg54 ,sometimes aft] a beta decay ! residual nucleus f9ds itself ) a 8correct0 numb] ( neutrons & protons b ) an excess ( en]gy4 ,t is1 ! residual nucleus is n 9 its gr\nd /ate b is excit$4 ,?is happ5s 9 ab\t two ?irds ( ! kn[n cases ( beta decay4 ,x happ5s1 = in/ance1 :5 ,n decays to ,o4 ,9 ?is situation ! excit$ nucleus w behave l an excit$ atom4 ,an excit$ atom1 ! read] w recall1 gets rid ( its excess en]gy by emitt+ electromagnetic radiation1 usually visible or ne>-visible light4 ,! excit$ nucleus w get rid ( its excess en]gy 9 exactly ! same way4 ,! only diff]5ce is t ! am\nt ( en]gy c>ri$ by ! electromagnetic radiation f ! nucleus is approximately a million times great] ?an t c>ri$ by ! electromagnetic radiation f ! atom--an indication ( ! l>ge quantity ( en]gy /or$ up inside ! nucleus4 ,su* en]getic electromagnetic radiation emanat+ f a nucleus is usually call$ a gamma ray4 ,gamma-ray emission1 or gamma decay1 l beta decay1 is an en]gy-releas+ process :i* *anges an un/able nucleus into a /able "o1 or at lea/ into a m /able "o4 ,m g5]ally1 any spontane\s en]gy-releas+ process 7:i* t5ds to /abilize ! nucleus7 is call$ radioactivity4 ,beta & gamma decay are two examples4 ,lat] on we %all consid] a ?ird example call$ alpha decay4 ,an alpha p>ticle is ! nucleus ( ! helium atom & consi/s ( two neutrons & two protons4 ,! decay ( a neutron & ! decay ( a proton appe> to be q analog\s processes4 ,actually !re is an important diff]5ce betwe5 ! two4 ,a free neutron--"o n conf9$ inside a nucleus--w decay into a proton & an electron2 b a free proton w n decay into a neutron & a positron4 ,?is diff]5ce is due to ! fact t ! proton has a slightly l[] weight ?an ! neutron & !re=e has less en]gy4 ,= ! proton to decay1 x mu/ be inside a nucleus :]e x c absorb "s en]gy f ! o!r protons & neutrons4 ,"o sometimes f9ds pairs ( nuclei :i* c\ld trans=m into ea* o!r by a proton-neutron 7or neutron-proton7 conv]sion2 nev]!less nei!r ( ^! conv]sions c occur 9 ! way we h j describ$4 ,! reason is t 9 a proton-neutron or neutron-proton conv]sion an additional electron or positron has to be emitt$4 ,n[ accord+ to ,e9/e9 ! mass ( ! electron or positron corresponds to "s en]gy 7,e mc71 & x may happ5 t nei!r ! neutron-proton trans=mation or ! proton-neutron trans=mation releases en\gh en]gy to make an electron or a positron4 ,9 su* cases "o ( ! inn]mo/ electrons ( ! atom may comb9e ) a proton to make a neutron4 ,su* an electron-capture process w always release en]gy provid$ t ! rev]se process--! trans=mation ( a neutron into a proton & an electron--is connect$ ) an en]gy deficit4 ,?us1 exclud+ ! possibility ( a really exact co9cid5ce ( two en]gies1 "o ( ! two trans=mations f neutron to proton or proton to neutron w always be possible4 ,x is "o ( ! mo/ firmly e/abli%$ laws ( nature t en]gy is always cons]v$4 ,"o w\ld !re=e expect t ! en]gy ( a beta ray w\ld be exactly equal to ! diff]5ce betwe5 ! en]gy ( ! nucleus be=e ! beta decay & ! en]gy ( ! nucleus aft] ! beta decay4 ,z a matt] ( fact ! en]gy ( a beta ray is f\nd nev] to be z great z ?is am\nt4 ,frequ5tly x is mu* less4 ,"s ( ! en]gy has app>5tly disappe>$ & ! suspicion has be5 voic$ t en]gy may n be cons]v$ aft] all4 ,x has turn$ out1 h[ev]1 t ! miss+ en]gy is smuggl$ out ( ! nucleus1 & ! smuggl] 7:o has only rec5tly be5 caught7 is call$ ! neutr9o4 ,! neutr9o is an electrically neutral p>ticle1 l ! neutron1 b its weight1 l ! weight ( a ray ( light1 is equal to z]o4 ,l su* a ray1 x moves ) ! velocity ( light4 ,! en]gy releas$ by ! nucleus 9 ! beta-decay process is %>$ m or less equally betwe5 ! neutr9o & ! beta ray4 ,we %all see lat] t ! electron gives rise to a numb] ( effects4 ,"s ( ^! are h>mful4 ,! neutr9o1 h[ev]1 is n 9 ! lea/ dang]\s4 ,l an ideal smuggl] x passes unnotic$ & practically )\t a trace4 ,x int]acts s slightly ) matt] t sev]al billion ( !m may g "r ?r\gh ! :ole sph]e ( our e>? be=e a s+le collision occurs4 ,v rec5tly ?is /range little p>ticle has upset "o ( our mo/ unque/ion$ concepts ab\t symmetry4 ,we h always believ$ t nature made no di/9ction betwe5 h] "r h& & h] left h&2 t = e natural process t exi/s1 !re exi/s also ! mirror image ( ?is process4 ,! neutr9o1 h[ev]1 is an exception4 ,x has a def9ite symmetry1 l a screw4#e ,?is fact may turn out to be mo/ important 9 ! developm5t ( sci5ce4 ,x has no be>+1 h[ev]1 on ! que/ions to be discuss$ 9 ?is book4 ,neutr9os rea* u f "s di/ant & hidd5 places l ! int]ior ( our sun & ( explod+ />s4 ,x may become possible to use neutr9os z mess5g]s to reveal ! k9d ( nucle> reactions f :i* ! en]gy ( ! />s is d]iv$4 ,neutr9os are also emitt$ e "t we release "s nucle> en]gy4 ,among all ! rem>kable practical consequ5ces ( nucle> en]gy1 ! neutr9os h a unique di/9ction3 !y are nev] useful1 & !y are nev] h>mful4 ,!y h n ev5 be5 suspect$ ( any mis*ief4 ,,*apt] ,,iv ,! ,law ( ,radioactive ,decay ,a radioactive nucleus is "o t w ev5tually dis9tegrate & release "s en]gy4 ,b :58 ,"o might imag9e t a radioactive nucleus w\ld beg9 to 8age0 f ! mom5t ( its bir?1 & t aft] ! passage ( a pr$et]m9$ "t1 ! dis9tegration process w\ld take place4 ,?is is h[ radioactivity might "w 9 a det]m9i/ic univ]se4 ,:at actually happ5s to a radioactive nucleus1 h[ev]1 is mu* m int]e/+4 ,at any in/ant ( its life1 ! radioactive nucleus has "s probability ( dis9tegrat+ 9 ! next second4 ,?is probability is unaffect$ by its age4 ,no matt] h[ long ! nucleus has liv$1 its *ance ( dis9tegrat+ 9 ! next second is always ! same4 ,x is z if a game ( r\lette 7 be+ play$4 ,! :eel sp9s1 & if its numb] comes up1 ! nucleus dis9tegrates 9 ! fir/ second4 ,if n1 ! :eel sp9s aga94 ,ea* "t ! :eel sp9s !re is "s probability ( its numb] com+ up4 ,! precise value ( ?is probability is a *>act]i/ic ( ea* p>ticul> radioactive species4 ,! high] ! probability1 ! m rapidly ! nucleus may be expect$ to dis9tegrate4 ,b a giv5 nucleus ne$ n d at any p>ticul> "t :at is expect$ ( x4 ,! notion ( probability 7or *ance7 has mean+ only :5 appli$ to a l>ge numb] ( cases4 ,to say t a giv5 nucleus has "o *ance 9 a hundr$ ( decay+ 9 ! next second means t out ( "s l>ge numb] 7say #ajj million7 ( su* radioactive nuclei1 "o p] c5t 7"o million7 w decay 9 ! next second4 ,b x is absolutely impossible to say be=eh& :i* nuclei w be ! ones to decay4 ,a p>ticul> nucleus may decay imm$iately or only aft] "s v long "t4 ,! collection z a :ole1 h[ev]1 w always d ! expect$ ?+4 7,?is is ! pr9ciple on :i* insurance companies op]ate47 ,! situation is be/ describ$ 9 t]ms ( a "t span :i* is call$ ! half-life ( ! radioactive species4 ,! half-life is def9$ z ! am\nt ( "t :i* is requir$ = "o half ( a l>ge numb] ( id5tical radioactive nuclei to dis9tegrate4 ,x makes no diff]5ce :at ?is l>ge numb] is1 provid$ only t x is l>ge en\gh4 ,if ! numb] is n l>ge en\gh1 fluctuations w occur1 & in/ead ( #ej p] c5t ( ! nuclei decay+ dur+ ! p]iod ( a half-life1 x may be #dj p] c5t or #fj p] c5t4 ,z a matt] ( fact ! #dj p] c5t to #fj p] c5t limits correspond to a sample size ( ab\t #ajj nuclei4 ,= #aj1jjj nuclei1 ! limits w be #di p] c5t to #ea p] c5t4 ,! numb] ( radioactive nuclei ) :i* we cu/om>ily deal1 is ab\t #aj 7#ajj1jjj1jjj1jjj1jjj1jjj1jjj1jjj74 ,?is is ! numb]1 = example1 ( radioactive nuclei 9 ab\t an ounce ( radium4 ,= su* a l>ge numb] ( nuclei ! deviation f #ej-p]-c5t decay dur+ a half-life w be utt]ly negligible4 ,?us we live 9 a univ]se :i*1 on a macroscopic scale1 appe>s ord]$ & subject to exact laws2 :ile und]ly+ ^! laws1 on a microscopic scale1 nature plays out a game ( *ance1 full ( r&omness & unc]ta9ty 9 ! individual case4 ,we may draw a graph %[+ h[ ,n1 ! numb] ( ! rema9+ radioactive nuclei1 v>ies ) ! "t t4 ,! graph %[s t3 9 ! fir/ half-life ,t1 half ( ! orig9al numb] ,n ( radioactive nuclei decay4 ,9 ! second half-life1 half ( ^? rema9+ decay1 & s on4 ,aft] ! "t ,t1 "o half ( ! orig9al radioactive nuclei /ill rema92 aft] #b,t1 "o qu>t] rema92 & s =?4 ,illu/ration3 uncaption$ ,diff]5t radioactive species h diff]5t half-lives4 ,_m are only a small fraction ( a second2 "s are billions ( ye>s4 ,n decays to ,o 7plus an electron & a neutr9o7 ) a half-life ( ab\t eight seconds4 ,a free neutron decays into a proton1 an electron1 & a neutr9o ) a half-life ( #ac m9utes4 ,/rontium ) weight #ij 7,sr7 und]goes a beta decay ) a half-life ( #bh ye>s4 7,?is is an isotope t is n f\nd any:]e 9 nature1 b is made 9 fairly l>ge quantities 9 ! fission process47 ,potassium ) weight #dj 7,k71 :i* is pres5t 9 ! am\nt ( #j4ja p] c5t 9 ord9>y potassium1 has a half-life ( "o billion ye>s4 ,x has presumably be5 left ov] f ! "t :5 ! primordial elem5ts 7 =m$4 ,half-lives = gamma decay are extremely %ort by comp>ison to ^? = beta decay4 ,!y usually am\nt to a small fraction ( a second4 ,radioactivity is *>act]iz$ by ! k9d ( p>ticle emitt$ f ! nucleus 7our examples1 s f>1 h be5 ( beta & gamma p>ticles71 by ! en]gy possess$ by ?is p>ticle1 & by ! half-life 9 :i* ! radioactive decay takes place4 ,! biological haz>d f radioactivity dep5ds on all ?ree ( ^! *>act]i/ics4 ,no matt] :e!r ! radioactive nuclei are produc$ 9 an atomic explosion or 9 an atomic reactor1 "s "t w 9 g5]al elapse be=e a human population c become expos$4 ,if ?is "t is long comp>$ to ! half-life ( ! radioactive species1 mo/ ( ! nuclei w h dis9tegrat$1 & ! haz>d w !reby be r$uc$4 ,if1 on ! o!r h&1 ! half-life is long comp>$ to ?is "t1 z well z to ! life-span ( a human be+1 ! rate at :i* dis9tegrations occur w be l[1 & aga9 ! haz>d w be r$uc$4 ,9 %ort ! dang]\s half-lives are ! int]m$iate ones1 n too long1 n too %ort4 ,sr is an example4 ,,*apt] ,v ,breakup ( ! ,nucleus ,! positive electric *>ges )9 an atomic nucleus repel "o ano!r4 ,9 ! mo/ heavily *>g$ nuclei ?is repulsion becomes s great t ! nucleus c break into two p>ts1 simultane\sly releas+ a consid]able am\nt ( en]gy4 ,9 ! case ( spontane\s nucle> fission ! two p>ts are m or less equal 9 size4 ,9 ! process ( alpha decay "o ( ! p>ts 7! alpha p>ticle7 is mu* small] ?an ! o!r4 ,an alpha p>ticle consi/s ( two neutrons & two protons & is id5tical ) ! nucleus ( ! helium atom4 7,! symbol = ?is nucleus is ,he47 ,s9ce two neutrons & two protons c simultane\sly occupy ! l[e/ en]gy /ate1 ! alpha p>ticle is an especially /able nucle> unit4 ,z a result1 f "t to "t 9 heavy nuclei1 two neutrons & two protons w coalesce into an alpha p>ticle1 :i* may !n attempt to escape4 ,9 attempt+ to escape f ! nucleus1 h[ev]1 an alpha p>ticle enc\nt]s consid]able resi/ance because ( ! %ort-range nucle> attraction ( ! o!r neutrons & protons4 ,?is resi/ance :i* an alpha p>ticle exp]i5ces 9 try+ to leave ! nucleus is usually ref]r$ to z an 8en]gy b>ri]40 ,if ! alpha p>ticle c\ld acquire a little additional en]gy1 x w\ld be able to ov]come ! b>ri] & get away f ! nucle> attraction4 ,once outside ! nucleus1 j beyond ! rea* ( ! nucle> attraction1 ! alpha p>ticle w\ld be accel]at$ viol5tly outw>d by ! l>ge electrical repulsion betwe5 its two protons & ! o!r protons 9 ! residual nucleus4 ,illu/ration3 ,h[ an alpha p>ticle escapes f ! nucleus4 ,f ,a to ,b x goes 8uphill10 los+ spe$4 ,at ,b its spe$ is z]o & x almo/ always turns ar\nd4 ,) a small probability x may sneak ?r\gh ! en]gy b>ri] ,b to ,c4 ,beyond ,c1 x is repell$ & em]ges ) increas+ spe$4 ,! alpha p>ticle ne$s "s extra en]gy to escape4 ,accord+ to ! laws ( old] physics !re is no possibility = x to obta9 ?is extra en]gy & !re=e escape is impossible4 ,b ! m newly discov]$ laws gov]n+ ! motion ( neutrons & protons 7! laws ( quantum me*anics7 are n s /r+5t2 !y p]mit ! alpha p>ticle to use 8borr[$0 en]gy to ov]come ! en]gy b>ri]4 ,( c\rse ! alpha p>ticle mu/ always repay ! loan--:i* x c easily d out ( ! l>ge fund ( electric en]gy t is releas$ :5 x gets out ( ! repulsive range ( ! residual nucleus4 ,!re is no int]e/ on ! loan4 ,su* en]gy loans are n automatically grant$ 9 nature4 ,!re are two factors :i* make ! loan improbable3 if ! am\nt is big or if ! t]m is long4 ,^! re/rictions effectively limit ! p>ticles :i* may apply = an en]gy loan4 ,objects ( great size & weight are unable to qualify1 b ! small p>ticles ( ! atomic _w (t5 d4 ,! m en]gy c>ri$ (f by ! alpha p>ticle aft] ! alpha decay1 ! less en]gy mu/ be borr[$ 9 ord] to ov]come ! b>ri]1 & ! m rapidly ! decay may be expect$ to occur4 ,s s5sitive is ! decay to ! en]gy ( ! alpha p>ticle1 t an alpha p>ticle c>ry+ twice ! en]gy is emitt$ a hundr$ trillion times fe/]4 ,half-lives = alpha decay v>y f a fraction ( a second to billions ( ye>s4 ,b ev5 ! %orte/ half-life = alpha decay is rem>kably long comp>$ to ! "t requir$ = ! alpha p>ticle to cross ! nucleus4 ,?is means t ! alpha p>ticle makes a trem5d\s numb] ( attempts to escape f ! nucleus be=e x actually succe$s4 ,accord+ to ! old] classical !ory ! alpha process %\ld nev] occur1 & 9 fact x occurs ) a v small probability4 ,a s+le alpha decay is n usually a suffici5t process to br+ ab\t /ability ( ! daught] nucleus4 ,a :ole *a9 ( radioactive decays is usually requir$ be=e /ability is a*iev$4 ,mo/ nuclei :i* emit alpha p>ticles belong to "o ( ^! radioactive decay *a9s4 ,! heavy nuclei = :i* alpha decay occurs all conta9 a l>ge excess ( neutrons4 ,s9ce ! alpha p>ticle c>ries (f exactly two neutrons & two protons1 ! ratio ( ! numb] ( neutrons to ! numb] ( protons is increas$ 9 ! daught] nucleus4 ,?is has an un/abiliz+ influ5ce4 7,actually1 9 light] nuclei /ability requires t ! ratio ( neutrons to protons be clos] to unity47 ,! daught] nucleus is ?us apt to be beta-active1 conv]t+ a neutron into a proton 7plus an electron & a neutr9o7 9 ord] to decrease its ratio ( neutrons to protons4 ,9 ?is way a *a9 ( radioactive decays may occur1 m or less alt]nat+ betwe5 alpha & beta emissions1 ) gamma rays be+ occasionally emitt$ also4 ,!re are f\r radioactive *a9s4 ,"o ( !m />ts ) ! abundant isotope ( uranium1 ,u4 ,?is isotope und]goes a few alpha decays & a c\ple ( beta decays to become radium1 :i* has a *>ge ( #hh & a weight ( #bbf4 ,all ! radium 9 ! _w is produc$ 9 ?is mann] z a daught] product 9 ! fif? decay ( ! *a94 ,aft] a numb] ( fur!r decays1 /able lead 7weight #bjf7 is produc$ & ! *a9 t]m9ates4 ,! o!r *a9s are simil> to ! ,u *a91 ?\gh n q z long4 ,"o *a9 />ts ) ! r>e isotope ( uranium1 ,u2 ano!r />ts ) ! isotope ( ?orium t weighs #bcb4 ,bo? ( ^! t]m9ate 9 /able isotopes ( lead4 ,9 all cases ! fir/ decay ( ! *a9 has a v long half-life4 ,! half-life ( ,u is #d4e billion ye>s2 ( ,u1 #gaj million ye>s2 & ( ?orium1 #ad billion ye>s4 ,! f\r? radioactive *a9 has be5 made 9 ! laboratory b is n f\nd 9 nature because its fir/ isotope1 neptunium ) weight #bcg1 has too %ort a half-life4 ,x decays 9 two million ye>s & all ! o!r memb]s ( ! *a9 live = ev5 %ort] p]iods4 ,?us ! neptunium *a9 decay$ long ago1 :]eas ! ?ree o!r *a9s h surviv$ f ! "t :5 ! elem5ts 7 made4 ,x is int]e/+ to notice t ! less] abundance ( ,u1 z comp>$ ) ,u1 is connect$ ) its %ort] half-life4 ,assum+ t comp>able am\nts ( bo? isotopes 7 pres5t at ! beg9n+ ( ! univ]se 7& !re is good reason to believe t ?is 0 ! case71 "o w\ld expect to f9d significantly less ,u ?an ,u aft] a p]iod ( a few hundr$ million ye>s4 ,aft] #gaj million ye>s 7! half-life = ,u7 only "o half ( ! orig9al numb] ( ,u nuclei w\ld /ill exi/4 ,b #ij p] c5t ( ! orig9al ,u nuclei 7half-life #d4e billion ye>s7 w\ld rema94 ,f ! pres5tly obs]v$ ratio ( ,u to ,u nuclei 7#a to #aci71 x may be calculat$1 us+ ! law ( radioactive decay1 t #f billion ye>s ago natural uranium consi/$ ( equal p>ts ( ,u & ,u4 ,! age ( ! univ]se is hotly debat$4 ,) ea* pass+ ye> ! univ]se seems to be a billion ye>s old]4 ,"r n[ six billion ye>s does n seem widely (f ! m>k4 ,natural radioactivity occurs ma9ly among ! heavy elem5ts1 b !re are a few light elem5ts t are naturally radioactive4 ,( ^!1 potassium is an especially int]e/+ "o because x c decay ei!r by electron emission or by electron capture4 ,! processes are3 potassium calcium electron neutr9o1 7#a4a billion ye>s7 & potassium electron argon neutr9o4 7#aa billion ye>s7 ,calcium & argon are bo? /able nuclei4 ,! second reaction is foll[$ imm$iately by a gamma ray emission f ! argon4 ,! "o p] c5t ( argon f\nd 9 ! e>?'s atmosph]e comes almo/ entirely f ! second reaction4 ,^! radioactivities are also int]e/+ because appreciable am\nts ( potassium are always pres5t 9 human tissue4 ,all nuclei at ! heavy end ( ! p]iodic sy/em are radioactive alpha emitt]s4 ,uranium1 = example1 has no /able isotopes2 !y all und]go alpha decay4 ,b !re is ano!r mode ( spontane\s decay ( uranium1 :i* is mu* less frequ5t ?an alpha decay b is ( mu* great] practical importance4 ,?is is ! fission process4 ,! fission process is j l alpha decay 9 t ! nucleus breaks up into two fragm5ts4 ,! ma9 diff]5ce betwe5 ^! processes is 9 ! relative weights ( ! fragm5ts4 ,9 ! alpha decay ( ,u1 = in/ance1 "o fragm5t has a weight ( f\r & ! o!r #bcd4 ,9 ! fission process ! fragm5ts t5d to be m ne>ly equal 9 weight4 ,= example1 "o may weigh #ij & ! o!r #adh4f ,o!r weight comb9ations are also possible4 ,! explanation ( spontane\s fission is 9 ess5ce ! same z t ( alpha decay4 ,spontane\s fission1 h[ev]1 is a less probable process because ! two fragm5ts are m /rongly b\nd to ea* o!r by ! nucle> =ces ?an !y are 9 alpha decay4 ,m en]gy mu/ be borr[$1 & x mu/ be borr[$ = a long] t]m 9 ord] to p5etrate ! en]gy b>ri]4 ,! relative likelihoods ( spontane\s fission & alpha decay c be appreciat$ f ! foll[+ fact4 ,9 "o h\r 9 a gram ( ,u !re occur ab\t #de million alpha decays b only ab\t #be spontane\s fissions4 ,once ! en]gy b>ri] has be5 ov]come1 ! en]gy releas$ 9 alpha decay or spontane\s fission is proportional to ! *>ges on ! two fragm5ts4 ,= alpha decay1 ! product ( ! *>ges is #b #ij #ahj2 = spontane\s fission1 ?is product w typically be ab\t #dj #eb #b1jhj4 ,h5ce "o might expect ! fission en]gy release to be #aj to #ae times great] ?an ! alpha en]gy release4 ,z a matt] ( fact ! fission en]gy release is ev5 great] ?an ?is e/imate indicates1 be+ ab\t #cj to #ej times great] ?an ! alpha en]gy release4 ,t s l>ge an am\nt ( en]gy is releas$1 is a v important feature ( ! fission process f ! po9t ( view ( practical utilization ( atomic en]gy4 ,be+ at ! end ( ! p]iodic sy/em1 uranium requires a l>ge ratio ( neutrons to protons = its greate/ /ability4 ,! fission fragm5ts1 h[ev]1 lie 9 ! middle ( ! sy/em ( elem5ts1 requir+ a mu* small] ratio ( neutrons to protons = /ability4 ,?is has two consequ5ces4 ,"o is t ! fragm5ts !mselves may be expect$ to be un/able4 ,!y w und]go beta decay 7electron emission7 sev]al times consecutively be=e a /able comb9ation ( neutrons & protons is rea*$4 ,?is radioactivity ( ! fission products con/itutes a pot5tial haz>d 9 any practical application ( fission atomic en]gy4 ,9 lat] *apt]s ( ?is book we %all consid] p>ticul>ly ! possible haz>d f ! fall\t ( radioactive fission products creat$ 9 atomic explosions1 & also ! haz>d associat$ ) ! op]ation & ma9t5ance ( atomic reactors4 ,! second consequ5ce ( ! neutron excess is t neutrons may boil (f f ! fragm5ts imm$iately aft] ! fission process has occurr$4 ,?is c happ5 because a lot ( disord]ly int]nal motion is g5]at$ by ! fission process )9 ! fragm5ts1 & ^! fragm5ts d n h a p>ticul>ly /rong hold on _! neutrons4 ,! practical value ( ! releas$ neutrons is some?+ we %all discuss at l5g? 9 a lat] *apt]4 ,= ! pres5t we m5tion only t ^! neutrons provide ! me*anism :]eby a *a9 reaction is made possible4 ,spontane\s fission & alpha decay are responsible = ! fact t elem5ts ) *>ge great] ?an #ib are n f\nd 9 nature4 ,!re is little d\bt t ^! elem5ts 7 made 9 ! beg9n+4 ,b !y h long s9ce decay$4 ,an int]e/+ case ( spontane\s nucle> fission is cali=nium 7*>ge #ih71 ) a half-life ( #ee days4 ,?is isotope is =m$ 9 l>ge quantities 9 c]ta9 /ell> explosions call$ sup]-novae4 ,once 9 a mill5nium "o ( a collection ( a billion />s fl>es into incr$ible brilliance4 ,= a few weeks ?is s+le /> %9es ) ! comb9$ en]gy & lu/] ( a billion ord9>y />s--!n x fades away gradually4 ,su* a 8new0 /> 7nova71 ) ! greate/ p[] ( radiation1 is call$ a 8sup]-nova40 ,we believe t _m nucle> reactions take place 9 a sup]-nova4 ,x has be5 obs]v$ t a few weeks aft] ! initial outbur/ ( light1 ! int5sity ( light is r$uc$ almo/ exactly by a factor ( two e #ee days = a ye> or s4 ,?is is precisely :at w\ld be expect$ if ! en]gy g5]at$ 9 ! /> dur+ ?is "t 7 due to ! spontane\s fission ( cali=nium4 ,"h we see a model ( :at happ5s to naturally radioactive elem5ts4 ,( ^! we h reta9$ on e>? only ! ones ) ! longe/ half-lives1 l uranium1 ?orium1 & potassium4 ,,*apt] ,,vi ,reactions ,betwe5 ,nuclei ,! al*emi/s tri$ to trans=m "o elem5t into ano!r artificially4 ,!y us$ heat1 !y us$ *emicals2 !y ev5 us$ wit*craft4 ,!y fail$4 ,_! simple/ me?od--to heat ! sub/ance 9 ord] to trans=m x--0 really correct4 ,! tr\ble 0 t _! temp]atures 7 too l[ by a factor ( m ?an #aj1jjj4 ,:at is ne$$1 is a temp]ature ( ! ord] ( t5s ( millions ( degrees4 ,at su* high temp]atures two nuclei may occasionally approa* ea* o!r 9 spite ( ! electrical repulsion betwe5 !m4 ,sometimes !y may ev5 get close en\gh to ea* o!r to und]go a nucle> reaction4 ,?is1 ( c\rse1 happ5s ) lea/ difficulty if ! nucle> *>ge is small4 ,hydrog5 nuclei1 :i* c>ry *>ge #a1 p>ticipate 9 su* reactions mo/ easily4 ,9 ! int]ior ( />s temp]atures range f ab\t #aj to #ajj million degrees1 & nucle> reactions d occur4 ,! reaction responsible = ! production ( en]gy 9 ! />s is3 #d;,h ,he en]gy ,f\r protons comb9e to make an alpha p>ticle ) a release ( en]gy4 ,actually ?is reaction does n take place all at once b sev]al /eps are requir$4 ,t en]gy %\ld be releas$1 "o expects f ! fact t ! alpha p>ticle is v /able4 ,any process 9 :i* light nuclei comb9e to =m a heavi] nucleus ) a release ( en]gy is kn[n z 8fusion40 ,! p>ticul> fusion process t goes on 9 ! />s releases its en]gy 9 _m =ms3 z positrons1 neutr9os1 electromagnetic radiation1 & motion ( ! react+ p>ticles4 ,! positrons also c>ry (f ! excess *>ge ( ! reaction4 ,! neutr9os fly ?r\gh ! /> )\t int]act+1 c>ry+ _! en]gy away into out] space1 probably nev] aga9 to make contact ) ! mat]ial univ]se4 ,! rema9d] ( ! fusion en]gy is deposit$ )9 ! />'s int]ior1 :i* is ?us kept hot en\gh s t ! fusion reaction c keep go+4 ,! "n 8!rmonucle>0 is appropriately appli$ to ?is type ( reaction4 ,a lot ( ef=t & imag9ation is be+ devot$ to ! problem ( mak+ a controll$ !rmonucle> reaction4 ,! motivation = ?is project comes f ! fact t good !rmonucle> fuels1 su* z deut]ium 7,h71 are abundant & *eap4 ,!re is en\gh deut]ium 9 ! oceans ( ! _w to supply man's en]gy ne$s = _m millions ( ye>s4 ,"o difficulty1 ( c\rse1 is to f9d a conta9] = ! reaction4 ,ev5 "u /ell> conditions ! rate ( fusion reactions is n v great4 ,x takes approximately a billion ye>s = only "o p] c5t ( ! nuclei to react4 ,consequ5tly ev5 high] temp]atures ?an ^? f\nd 9 />s are requir$ to produce l>ge am\nts ( en]gy 9 a %ort "t4 ,b no kn[n mat]ials c )/& temp]atures ( m ?an a few ?\s& degrees c5tigrade4 ,"o idea is to keep ! 8burn+0 fuel away f mat]ial walls by means ( magnetic fields4 ,is !re a way to make nuclei react )\t ! extreme temp]atures ne$$ 9 ! !rmonucle> reactions8 ,:at "o is really try+ to d is br+ two nucle> p>ticles into intimate en\gh contact s t ! nucle> =ces c act betwe5 !m4 ,!re is no reason :y "o %\ld n use a cold t>get mat]ial1 :i* is bomb>d$ f ! outside by en]getic nucle> projectiles1 = example protons or alpha p>ticles4 ,! projectiles1 if !y are en]getic en\gh1 c ov]come ! electrical repulsion ( ! t>get nuclei1 & !y actually c p5etrate4 ,! result+ 8comp\nd0 nuclei w\ld ei!r be un/able & dis9tegrate in/antane\sly1 or else be almo/ /able 7i4e41 radioactive7 & dis9tegrate aft] "s p]iod ( "t4 ,9 ei!r case nuclei ( new elem5ts w\ld probably be =m$ 9 ! reaction4 ,?is proc$ure s\nds simple1 b x has its difficulties4 ,illu/ration3 ,int]ior ( ! sun4 ,! !rmonucle> reactions take place ma9ly 9 ! v hot1 v d5se c5tral region 7%ad$74 ,?is region is ab\t #bj1jjj miles 9 radius & has a d5sity approximately #hj times ! d5sity ( wat]4 ,! ma9 difficulty is t ! nucleus is a v t9y t>get4 ,its area is ab\t #ajj million times small] ?an ! area ( ! atom z a :ole4 ,if a piece ( matt] is bomb>d$ by an en]getic p>ticle1 *ance alone w det]m9e :e!r ! p>ticle is direct$ t[>d a nucleus4 ,to be sure1 if ! p>ticle misses ! nucleus ( "o atom1 x /ill has ! opportunity ( hitt+ ! nuclei ( o!r atoms :i* may lie 9 its pa?4 ,x does n h _m su* opportunities1 h[ev]1 because1 be+ *>g$1 x con/antly int]acts ) ! atomic electrons1 :i* gradually absorb en]gy caus+ ! p>ticle to sl[ d[n4 ,z ! p>ticle sl[s d[n1 its *ance ( hitt+ a nucleus decreases1 ev5 if x is head+ directly t[>d "o1 because ( ! repulsion betwe5 its *>ge & t ( ! nucleus4 ,unless ! p>ticle has suffici5t spe$1 x _c ov]come ?is repulsion4 ,*>g$ p>ticles may be giv5 ! requir$ spe$s by accel]at+ !m ?r\gh l>ge electric fields4 ,if a unit *>ge is accel]at$ ?r\gh a pot5tial diff]5ce ( "o volt1 x acquires an en]gy ( "o electron-volt4 ,! en]gies requir$ = nucle> bomb>dm5t are ( ! ord] ( sev]al million electron-volts1 :i* c be provid$ by atom-sma%+ ma*9es su* z ! cyclotron4 ,ev5 at su* high en]gies v few ( ! nucle> projectiles actually f9d _! way to a t>get nucleus4 ,mo/ ( !m are sl[$ d[n by ! electrons1 wa/+ _! en]gy 9 heat+ up ! t>get mat]ial4 ,p]haps "o p>ticle out ( a million w be lucky en\gh to induce a nucle> reaction4 ,if ! purpose ( ! nucle> accel]at+ ma*9es 7 to produce *eap en]gy1 !y w\ld n be ( mu* value4 ,a nucle> reaction may typically release five to #bj million electron-volts ( en]gy4 ,b to obta9 ?is reaction1 a million p>ticles _h to be accel]at$ to en]gies ( sev]al million electron-volts4 ,! recov]able & useable en]gy w be only a m9ute fraction ( ! total inve/$4 ,on ! o!r h&1 z a tool = sci5tific discov]y1 ! atom-sma%]s h be5 ( great importance4 ,t "o ev5t 9 a million has giv5 u mu* ( our k ( nucle> physics4 ,! a*ievem5t ( nucle> reactions by p>ticle bomb>dm5t did n actually wait on ! inv5tion ( man-made accel]at+ ma*9es4 ,en]getic alpha p>ticles are available f ! radioactive decay ( heavy elem5ts4 ,9 #aiai ,erne/ ,ru!r=d us$ su* radioactive elem5ts z a s\rce ( alpha p>ticles4 ,! alpha p>ticles 7 made to bomb>d ord9>y nitrog51 caus+ ! reaction3 ,he ,n ,o proton 7#b protons7 7#g protons7 7#h protons7 7#b neutrons7 7#g neutrons7 7#i neutrons7 ,t is1 an alpha p>ticle plus a nitrog5 nucleus react to produce a nucleus ( 7/able7 oxyg5 plus a proton4 ,oxyg5 is a nucleus ) #h protons & #i neutrons4 ,! ord9>y abundant =m ( oxyg5 has #h protons & #h neutrons4 ,natural oxyg5 conta9s a small am\nt ( oxyg54 ,lat]1 9 #aicd1 ,ir5e ,curie ,joliot 7! daught] ( ! discov]] ( radium1 ,madame ,curie7 & h] husb&1 ,fr$]ic ,joliot1 us$ naturally available alpha p>ticles to make artificial radioactive nuclei = ! fir/ "t4 ,! reaction 03 ,he alum9um phosphorus neutron 7#b protons7 7#ac protons7 7#ae protons7 7#b neutrons7 7#ad neutrons7 7#ae neutrons7 ,phosphorus is an un/able nucleus & emits a beta ray 7a positron7 to become silicon 7:i* is /able74 ,! half-life = ?is decay is ab\t #b4e m9utes4 ,! ,joliots' reaction 0 ! fir/ in/ance 9 :i* man _h produc$ radioactivity & kn[n x4 ,actually cyclotrons _h be5 produc+ radioactivity 9 good abundance = ! prec$+ two ye>s--b physici/s _h be5 unaw>e ( ?is fact4 ,x is amus+ t nature has also provid$ u ) an atom-sma%+ ma*9e & inde$ "o t produces f> great] en]gies ?an any app>atus yet devis$ by man4 ,?is ma*9e op]ates on ! pr9ciple ( fluctuat+1 turbul5t magnetic fields 9 int]/ell> space4 ,cosmic p>ticles--ma9ly protons1 b also "s alpha p>ticles & ev5 heavi] nuclei--are accel]at$ by ^! *ang+ magnetic fields & hurl$ occasionally into ! e>?'s atmosph]e4 ,! en]gies ( ^! cosmic p>ticles are enorm\s1 rang+ f billions ( electron-volts to values a million times high]4 ,:5 a cosmic p>ticle gets inside ! e>?'s atmosph]e1 x does n g f> be=e collid+ ) a nucleus ( nitrog5 or oxyg54 ,out ( ?is nucle> ev5t em]ge all ! fundam5tal p>ticles m5tion$ s f>1 & "s o!rs kn[n z mesons4 ,mesons are p>ticles :i* may be *>g$ or neutral1 & :i* h a weight a few hundr$ times t ( ! electron4 ,"s ( ^! p>ticles are believ$ to be connect$ ) ! =ces t hold ! nucleus toge!r4 ,! nucle> debris f ! collision w itself be v en]getic & w fur!r disrupt o!r nitrog5 & oxyg5 nuclei4 ,!re soon develops a cascade ( electrons1 positrons1 mesons1 neutrons1 protons1 & electromagnetic radiation mov+ t[>d ! surface ( ! e>?4 ,ab\t once a second e squ>e in* ( ! e>?'s atmosph]e receives su* an en]getic p>ticle f out] space4 ,! cascade t results c>ries p5etrat+ radiations to ! surface ( ! e>?4 ,all liv+ organisms are con/antly subject$ to ?is radiation backgr\nd4 ,x is an important fact t ! int5sity ( ?is radiation is r$uc$ 9 its passage ?r\gh ! air1 & inhabitants ( ,d5v] or ,lima receive m cosmic radiation ?an ! inhabitants ( ,los ,angeles or ,new ,york4 ,"s neutrons made by collisions ( ! prim>y cosmic p>ticles 9 ! atmosph]e may collide ) nuclei ( nitrog54 ,:5 ?is happ5s1 ! foll[+ reaction occurs3 nitrog5 neutron c>bon proton 7#g protons7 7#f protons7 7#g neutrons7 7#h neutrons7 ,c>bon is a radioactive electron emitt] ) a half-life ( #e1fjj ye>s4 ,?is half-life is long en\gh s t mu* ( ! c>bon 9 ! _w today 0 probably made t5 to tw5ty ?\s& ye>s ago4 ,will>d ,libby /udi$ ?is process 9 a c>eful & quantitative way1 trac$ ! hi/ory ( ! radioactive c>bon f ! atmosph]e into liv+ be+s1 &1 by measur+ ! c>bon cont5t 9 hi/orical rema9s1 op5$ up a :ole new bran* ( ar*eology4 ,liv+ organisms brea! 9 c>bon 79 ! =m ( c>bon dioxide7 f ! air4 ,mo/ ( ?is c>bon is ord9>y /able c>bon2 a t9y fraction is radioactive c>bon4 ,! organism is unable to di/+ui% betwe5 ! two isotopes1 & takes 9 c>bon 9 ! same ratio to c>bon z exi/s 9 ! atmosph]e4 ,?is ratio p]si/s ?r\gh\t ! organism's lifetime1 b :5 ! organism dies & no m c>bon is assimilat$1 ! ratio beg9s to decrease z ! c>bon nuclei gradually dis9tegrate4 ,by obs]v+ ! ratio ( c>bon to c>bon 9 fossil rema9s & o!r ar*eological objects1 ! date at :i* dea? occurr$ c be calculat$4 ,9 ?is way ! age ( anci5t ,egyptian mummies has be5 f\nd1 & x has be5 %[n t "s sequoia wood is m ?an #a1ejj ye>s old4 ,by measur+ ! c>bon 9 trees t 7 kill$ by ! la/ advance ( glaciation1 & look+ into o!r rema9s ( life f ! la/ ice age1 x has be5 possible to %[ t ?is la/ ice age occurr$ only #aj1jjj ye>s ago--in/ead ( #bj1jjj ye>s1 z _h be5 previ\sly believ$4 ,c>bon-dat+ has !re=e ?or\ghly revis$ our ideas ab\t ! rapidity ) :i* ! empires kn[n to hi/ory h em]g$ f ! mo/ primitive conditions4 ,a crucial "p ( ! argum5t is t isotopes ( ! same elem5t are *emically indi/+ui%able4 ,an alt]native reaction :i* may occur :5 neutrons /rike nitrog51 is ,n neutron c>bon ,h 7#g protons7 7#f protons7 7#a proton7 7#g neutrons7 7#f neutrons7 7#b neutrons7 ,h1 triton1 is also radioactive1 und]go+ a beta decay to become ,he 7#b protons & #a neutron7 ) a half-life ( #ab4be ye>s4 ,tritons too c be us$ = dat+ old objects--= example1 old w9e4 ,! wat] 9 ! w9e _c be repl5i%$ ) cosmic-ray tritons aft] ! w9e has be5 bottl$4 ,?us fifty p] c5t ( ! tritons disappe> e #ab4be ye>s4 ,we h "h two examples ( nucle> reactions induc$ by neutron bomb>dm5t4 ,recall+ ! disadvantages ( *>g$ p>ticles z nucle> projectiles = al*emi/s1 x mu/ surely seem t neutrons w\ld be ideal = ?is purpose4 ,be+ *>geless1 !y are nei!r electrically repell$ by ! nuclei nor con/antly sl[$ d[n by en]gy-los+ collisions ) ! electrons4 ,! fate ( almo/ e neutron mov+ 9 a l>ge piece ( matt] is ev5tual collision ) a nucleus4#g ,neutrons are ideal nucle> projectiles1 except = "o ?+3 !y are h>d to get4 ,protons & alpha p>ticles are f\nd abundantly 9 nature z ! nuclei ( hydrog5 & helium atoms4 ,neutrons1 h[ev]1 are n f\nd 9 nature1 & 9 ! pa/ h be5 made 9 nucle> reactions t 7 !mselves initiat$ by *>g$ p>ticles4 ,= example1 ,he b]yllium ,c neutron 7#b protons7 7#d protons7 7#f protons7 7#b neutrons7 7#e neutrons7 7#f neutrons7 ,b n[ we enc\nt] aga9 ! difficulty associat$ ) *>g$ p>ticles4 ,only "o alpha p>ticle 9 a million und]goes a nucle> reaction to produce a neutron4 ,! neutron1 ( c\rse1 makes a nucle> reaction e "t4 ,ov]-all1 !n1 we obta9 two nucle> reactions p] million nucle> projectiles1 in/ead ( "o p] million4 ,) su* me?ods we are n s mu* bett] (f ?an ! old al*emi/s4 ,a *eap & pl5tiful s\rce ( neutrons w\ld1 h[ev]1 put ! al*emi/ 9 bus9ess4 ,9 ?is way "o c\ld make r>e elem5ts & radioactive isotopes1 & :at is m important1 he w\ld be able to utilize conc5trat$ nucle> en]gy4 ,,*apt] ,,vii ,fission & ! ,*a9 ,reaction ,neutrons are ideal projectiles = nucle> bomb>dm5t because !y c>ry no *>ge1 c approa* nuclei easily1 & int]act ) !m /rongly4 ,^! neutral p>ticles1 discov]$ by ,james ,*adwick 9 #aicb1 7 us$ soon aft]w>d by ,enrico ,f]mi & 8 collaborators to bomb>d mo/ ( ! elem5ts ( ! p]iodic table4 ,v (t5 9 ^! exp]im5ts a nucleus w\ld capture a neutron & become un/able ) too mu* weight = its *>ge4 ,/ability w\ld !n be re/or$ by a beta decay1 leav+ ! nucleus ) "o m unit ( *>ge ?an x _h to beg9 )4 ,9 #aicd ,f]mi tri$ ?is exp]im5t ) uranium1 *>ge #ib1 ! mo/ highly *>g$ elem5t kn[n at t "t4 ,he hop$ to make a transuranic elem5t ) *>ge #ic4 ,?r\gh\t ! exp]im5ts ! uranium 0 obs]v$ ) radioactive c\nt]s & f\nd to become f> m radioactive ?an uranium ord9>ily is 9 its natural /ate4 ,!re 0 no way to acc\nt = all ?is radioactivity except to assume t new elem5ts _h be5 =m$ 9 ! process ( neutron bomb>dm5t4 ,a *emical analysis reveal$ no elem5ts ) *>ges betwe5 #hf & #ia4 ,f ?is evid5ce ,f]mi conclud$ t no elem5ts ( *>ge less ?an #ib _h be5 made & !re=e ! radioactivity mu/ be due to *>ges great] ?an #ib4 ,he conclud$ t transuranic elem5ts _h be5 made 9 ! laboratory4 ,nei!r ,f]mi nor anyone else1 h[ev]1 0 happy ) ?is conclusion4 ,!re 0 f> too great a v>iety ( radioactivity = com=t4 ,x _h to be assum$ t n only 0 ! elem5t ) *>ge #ic be+ made1 b also elem5ts ) *>ges #id1 #ie1 & _m m4 ,?is 0 v h>d to und]/&4 ,ida ,noddack1#h a *emi/1 publi%$ a pap] propos+ an alt]native explanation ( ! exp]im5t3 t a nucleus ( uranium1 :5 x captures a neutron1 might break up into two fragm5ts t c\ld h any ( v>i\s weights & *>ges4 ,9 o!r words1 %e sugge/$ t ,f]mi _h produc$ nucle> fission4 ,f]mi1 h[ev]1 believ$ t ! fission process 0 an impossibility4 ,he _h a conv9c+ pro(1 bas$ on ! measur$ values ( ! weights ( nuclei & ! =mula ( ,e9/e91 ,e mc4 ,f ?is =mula ,f]mi calculat$ ! en]gy lib]at$ :5 uranium breaks into two pieces2 !n he took into acc\nt ! en]gy ( electric repulsion betwe5 ! pieces & f\nd t ! en]gy b>ri] 0 s l>ge t ! fission process c\ld n take place4 ,?is pro( 0 absolutely correct4 ,! only tr\ble 0 t ! measur$ values ( ! weights ( nuclei happ5$ to be inaccurate at t "t6 ,b = ?is accid5t1 fission w\ld h be5 discov]$ 9 #aicd in/ead ( #aich4 ,if x _h be51 ,nazi ,g]many might easily h be5 ! fir/ c\ntry to make ! atomic bomb4 ,at t "t "s ,g]man sci5ti/s 7 active 9 ! field ( milit>y applications4 ,! ,am]ican physici/s _h n yet turn$ mu* att5tion to ! subject4 ,an important feature ( ,f]mi's exp]im5t is ! l>ge am\nt & v>iety ( radioactivity t he f\nd4 ,! reason = ?is v>iety1 z we n[ "k1 is t ! fission process does n take place 9 a unique mann]4 ,! two prim>y fission fragm5ts are v r>ely ( equal weight & *>ge4 ,on ! av]age ! light] fragm5t weighs ab\t #ij1 & ! heavi] "o ab\t #adj4 ,sometimes ! light] fragm5t w weigh z little z #ge1 & ! heavi] "o z mu* z #afj4 ,z ! weight v>ies1 ( c\rse1 s also does ! *>ge4 ,! *>ge ( ! light] fragm5t av]ages #ch1 :i* is /rontium1 & ! heavi] "o #ed1 :i* is x5on4 ,all 9 all !re are m ?an a hundr$ diff]5t species ( nuclei repres5t$ among ! prim>y fission fragm5ts4 ,practically all ( ^! nuclei are radioactive & und]go ?ree or f\r dis9tegrations be=e rea*+ /ability4 ,ov]all !re=e1 sev]al hundr$ di/9ct radioactive species are creat$ by ! fission process 9 uranium4 ,elem5ts ) *>ges #dc & #fa 7:i* are n f\nd 9 nature7 h be5 id5tifi$ z fission products 9 fairly appreciable quantities4 ,mo/ ( ! fission products are %ort-liv$ electron & gamma emitt]s t c contribute only to ! local & imm$iate radioactive haz>d4 ,two ( ! long-liv$ products are abundant & important4 ,^! are cesium & /rontium4 ,cesium has a half-life ( #cj ye>s & emits a gamma ray ) an en]gy ( #j4f million electron-volts4 ,/rontium has a half-life ( #bh ye>s & emits an electron ) an av]age en]gy ( #j4bb million electron-volts4 ,! daught] nucleus 9 ?is process is yttrium1 :i* emits ano!r electron ) an av]age en]gy ( "o million electron-volts4 ,! half-life ( yttrium is #fd h\rs4 ,9 effect1 !re=e1 /rontium emits two electrons1 ea* ) an av]age en]gy ( #j4f million electron-volts4 ,= ! long-t]m radioactive haz>d1 p>ticul>ly ! _w-wide fall\t associat$ ) atomic explosions1 ! two isotopes cesium & /rontium are ! mo/ significant4 ,/rontium is ! m dang]\s to liv+ organisms because x is deposit$ 9 ! bones & reta9$ 9 ! body = long p]iods4 ,besides radioactivity !re is ano!r feature ( ! fission process :i* is s conspicu\s t x may seem h>d to und]/& h[ ,f]mi fail$ to notice x--namely ! l>ge am\nt ( en]gy releas$4 ,! fission ( a s+le nucleus ( uranium releases an en]gy ( #bjj million electron-volts z contra/$ ) ord9>y radioactive decay en]gies ( #e to #aj million electron-volts4 7,! en]gy releas$ f ! burn+ ( "o atom ( coal is only #d electron-volts47 ,( ! #bjj million electron-volts releas$ 9 fission1 ab\t #aj million g into gamma rays & neutrons creat$ 9 ! fission process itself4 ,?is en]gy contributes to ! imm$iate & local radiation dang]4 ,ano!r #bd million electron-volts g into radioactivity ( ! fission products1 & ( ?is1 ab\t half g into neutr9os1 :i* are nei!r dang]\s nor useful2 ! o!r half is c>ri$ by electrons & gives rise to ! delay$ radioactive haz>d4 ,b ! bulk ( ! en]gy1 ov] #afj million electron-volts1 goes into k9etic en]gy ( ! two prim>y fission fragm5ts4 ,( ?is am\nt1 #ajj million1 on ! av]age1 g to ! light] fragm5t4 ,"o hundr$ million electron-volt fission fragm5ts %\ld c]ta9ly h be5 notic$ by ,f]mi's radioactive c\nt]s--if !y _h be5 able to rea* ! c\nt]s4 ,! fragm5ts 7 n able to rea* ! c\nt]s1 h[ev]4 ,! reason is t ,f]mi 0 a c>eful work]4 ,he knew t 8 sample ( uranium w\ld emit "s radioactive p>ticles ev5 be=e neutron bomb>dm5t4 ,?is natural radioactivity he did n want to get mix$ up ) ! radioactivity t w\ld be produc$ 9 ! exp]im5t4 ,s he put an absorb+ foil betwe5 ! uranium sample & ! radioactive c\nt]s4 ,! fission fragm5ts c\ld n get ?r\gh ! foil4 ,x is amus+ t %ortly aft]w>d ano!r not$ physici/ repeat$ ,f]mi's exp]im5t1 b ?is "t )\t ! foil4 ,he report$ t he 0 unable to get any significant results because 8 c\nt]1 = reasons unkn[n1 />t$ to sp>k4 ,?us fission rema9$ a secret4 ,b 9 ,engl& ,leo ,szil>d obta9$ pat5t pap]s on ! nucle> *a9 reaction4 ,he po9t$ out t 9 "s nucle> reactions free neutrons might be releas$4 ,^! neutrons might !n succe$ 9 produc+ fur!r reactions :i* w\ld produce m neutrons4 ,provid$ t at lea/ "o neutron made 9 ea* reaction 7 able to induce a reaction 9 ano!r nucleus1 a *a9 reaction w\ld take place4 ,! ma9 problem1 ( c\rse1 0 to avoid excessive neutron losses4 ,!re are two ways 9 :i* ! losses ma9ly occur4 ,"o is by wa/eful1 nonreproductive capture 9 ! nuclei2 ! o!r1 by neutron leakage f ! mat]ial surface4 ,?is second loss1 ,szil>d %[$1 c\ld be m9imiz$ by us+ a suffici5tly l>ge am\nt ( *a9-react+ mat]ial4 ,! po9t is t a neutron born 9 a nucle> reaction mu/ travel on ! av]age a c]ta9 di/ance be=e x c produce ano!r reaction4 ,if ! size ( ! *a9-react+ mat]ial is mu* less ?an ?is di/ance1 practically all ( ! neutrons produc$ w be able to escape ?r\gh ! mat]ial surface1 & no *a9 reaction w be possible4 ,if ! size ( ! mat]ial is l>ge comp>$ to ?is di/ance1 ! leakage loss becomes negligible1 & ! possibility ( a *a9 reaction dep5ds entirely on ! magnitude ( ! fir/ k9d ( loss1 ! wa/eful captures 9 nuclei4 ,if ?is loss is n too great1 & a *a9 reaction is possible1 !re w be a critical size ( ! mat]ial at :i* on ! av]age exactly "o neutron p] reaction w be able to induce ano!r reaction4 ,a j critical *a9 reaction ( ?is k9d is :at is ne$$ = an atomic reactor4 ,if ! size ( ! mat]ial is great] ?an ! critical size1 on ! av]age m ?an "o neutron p] reaction w cause ano!r reaction & ! *a9 reaction w run away4 ,if1 = example1 two neutrons c cause ano!r reaction1 !re w be two neutrons aft] ! fir/ g5]ation1 f\r aft] ! second1 eight aft] ! ?ird1 & s =?4 ,?is is ! pr9ciple ( ! atomic bomb4 ,aft] ab\t #hj g5]ations1 an appreciable fraction ( all ! nuclei 9 ! mat]ial w h und]gone a nucle> trans=mation & s mu* en]gy w h be5 releas$ t ! mat]ial w n /ay toge!r ev5 = ! %ort "t ne$$ to produce ! next g5]ation4 ,! :ole mat]ial beg9s to fly ap>t1 ! sy/em becomes sub-critical1 & ! *a9 reaction /ops4 ,! entire process la/s only a fraction ( a microsecond4 ,?us ev5 be=e fission 0 discov]$1 ,szil>d laid ! basis = con/ruct+ ! atomic bomb & ! nucle> *a9 reactor4 ,z mat]ials 9 :i* a *a9 reaction might conceivably be made to occur he nam$ ?orium1 uranium & b]yllium4 ,on b]yllium he 0 wrong because ! mass ( ?is atom 0 incorrectly kn[n4 ,on ?orium1 8 guess 0 good4 ,on uranium1 he hit ! bull's eye4 ,f9ally 9 ,decemb] #aich ! secret broke4 ,hahn & ,/rassmann 9 ,g]many made a *emical analysis ( a uranium t>get t _h be5 expos$ to neutrons4 ,!y 7 f> m ?or\gh ?an previ\s inve/igators _h be51 & !y f\nd b>ium1 *>ge #ef1 :i* _h n be5 pres5t 9 ! t>get mat]ial be=e ! exp]im5t4 ,! only possible explanation 0 ! fission process4 ,)9 a few weeks ! viol5t kicks caus$ by ! fission products 9 c\nt]s 7 f\nd1 & 9 ! foll[+ days ?is exp]im5t 0 repeat$ ar\nd ! _w4 ,!re 0 no d\bt t neutrons c\ld induce fission 9 uranium nuclei4 ,a few m weeks1 & x 0 asc]ta9$ t ! fission process releas$ neutrons :i* might lead to m fissions4 ,! *a9 reaction1 h[ev]1 0 /ill f> f a reality4 ,niels ,bohr & ,john ,:eel] prov$ t a neutron c\ld n cause fission 9 ,u unless its en]gy 7 great] ?an ab\t "o million electron-volts4 ,:5 ! neutrons are fir/ made 9 ! fission process1 _m ( !m d h en]gies great] ?an "o million electron-volts4 ,b be=e !y c cause a fission1 !y usually make a few nonfission collisions ) uranium nuclei1 giv+ "p ( _! en]gy to ! nuclei & escap+ ) ! rema9d]4 ,! nuclei are !n left ) too little en]gy to und]go fission & ! neutrons ) too little en]gy to cause fissions 9 _! next enc\nt]s4 ,?us too few neutrons reproduce !mselves & no *a9 is possible4 ,bohr & ,:eel] sugge/$1 h[ev]1 t ! r>e isotope ( uranium1 ,u1 c und]go fission :5 any neutron1 ev5 a sl[ neutron1 hits x4 ,?us a *a9 reaction is possible 9 ,u4 ,?is 0 confirm$ exp]im5tally %ortly aft]w>ds by ,john ,dunn+ & ,alfr$ ,dri] & _! co-work]s at ,columbia ,univ]sity4 ,:y ! isotopes #bce & #bch behave s diff]5tly1 is n difficult to und]/&4 ,! #bce is m explosive & m prone to und]go fission ?an #bch because x is small] & !re=e its protons repel ea* o!r m /rongly4 ,m important /ill1 :5 a neutron is captur$ by #bce1 x acquires a great] k9etic en]gy by virtue ( ! %ort-range nucle> attraction ?an a neutron acquires :5 x is captur$ by #bch4 ,?is happ5s = ! simple reason t nuclei t5d to be m /able :5 !y h an ev5 numb] ( neutrons 7or protons7 ?an :5 !y h an odd numb]4 ,u1 hav+ an odd numb] ( neutrons1 is m eag] to receive an additional neutron ?an #bch1 :i* already has an ev5 numb] ( neutrons4 ,consequ5tly1 ! capture ( a sl[ neutron by #bce almo/ always ev5tuates 9 ! fission process2 :ile 9 #bch1 ! excess en]gy1 introduc$ by ! neutron1 is m]ely eject$ f ! nucleus 9 ! =m ( a gamma ray1 & ,u becomes ,u4 ,a *a9 reaction is possible 9 ,u 1 b x is necess>y to sep>ate ?is r>e isotope f ! abundant ,u4 ,! sep>ation process is any?+ b simple s9ce isotopes ( ! same elem5t are *emically indi/+ui%able4 ,ev5 ! weight diff]5ce 9 ?is case1 is little m ?an "o p] c5t4 ,bohr reject$ ! idea ( a l>ge-scale sep>ation ) ! rem>k3 8,y w\ld h to turn ! :ole c\ntry into a factory40 ,( c\rse x is n[ a matt] ( hi/ory t ! job 0 actually done "u ! ,manhattan project dur+ ,_w ,w> ,,ii4 ,dur+ ! w> ,bohr 7alias ,ni*olas ,bak]7 aga9 visit$ ! ,unit$ ,/ates & 0 %[n ! sep>ation plants4 ,he said3 8,y see ,i 0 "r4 ,y did turn ! c\ntry into a factory40 ,natural uranium conta9s ,u 9 ! ratio ( #a "p to #aci ( ,u4 ,x 0 hop$ at fir/ t ?is conc5tration w\ld be suffici5t to make a *a9 reaction1 & t ! exp5sive enri*m5t processes c\ld be avoid$4 ,?is seem$ possible because at en]gies ( a fraction ( an electron-volt ! neutrons are mu* m easily caught by ,u ?an by ,u1 :i* comp5sates = ! l[ conc5tration4 ,actually neutrons are sl[$ d[n until _! en]gy is z l[ z ! en]gy ( all o!r p>ticles p>ticipat+ 9 ! g5]al agitation caus$ by ! temp]ature4 ,?is en]gy is l[ en\gh = ! purpose4 ,h[ev]1 ! neutrons are made 9 ! fission process ) an en]gy ( ab\t a million electron-volts4 ,be=e !y sl[ d[n suffici5tly1 !y mu/ pass ?r\gh a /age 9 :i* _! en]gy is ab\t #g electron-volts4 ,9 ! neighborhood ( ?is en]gy1 x happ5s t ! ,u has an extremely high probability = captur+ a neutron & *ang+ into ,u4 ,ne> "s o!r en]gies1 simil> ?\gh small] absorption hurdles mu/ be pass$4 ,!re=e natural uranium by itself _c be us$ to make a *a9 reaction4 ,9 #aidj1 ,f]mi & ,szil>d1 work+ n[ 9 ! ,unit$ ,/ates1 f\nd a way ar\nd ?is difficulty4 ,_! trick 0 to mix ! natural uranium ) a mat]ial ^: nuclei are s lightweight t !y suff] a big recoil :5 /ruck by a neutron & ?us absorb a l>ge fraction ( ! neutron en]gy4 ,! neutron is ?us mod]at$ d[n to a l[ en]gy1 rapidly & 9 big en]gy jumps1 s t ei!r x does n sp5d mu* "t at ! unfavorable en]gies :]e x c be caught by ,u or else x misses ^! en]gies altoge!r4 ,by imb$d+ ! uranium 9 lumps 9 ! mod]at+ mat]ial in/ead ( mak+ a homog5e\s mixture ( ! two1 ! absorption c be circumv5t$ ev5 bett]4 ,= ! purpose ( mak+ a controll$ *a9 reaction1 "o may use ! me?od ( enri*m5t1 or ! me?od ( mod]ation1 or bo?4 ,b to produce a viol5t *a9 reaction1 an atomic bomb1 only ! enri*m5t me?od w "w4 ,! reason is t all ! en]gy ( ! bomb mu/ be g5]at$ 9 a "t t is z %ort z ! "t x takes ! bomb to fly ap>t1 :i* is a fraction ( a microsecond4 ,if natural uranium 7 us$1 ! reaction w\ld be sl[ & sluggi% & w\ld be ext+ui%$ be=e a sub/antial fraction ( ! nuclei c\ld h react$4 ,x is int]e/+ to consid] t *a9-react+ sub/ances c\ld h be5 obta9$ easily six billion ye>s ago1 be=e ! ,u _h "t to decay & become a r>e isotope4 7,! ,u 0 !n ab\t z abundant z ,u47 ,a *emical sep>ation w\ld /ill h be5 necess>y & s we d n ne$ to imag9e t *a9-react+ mixtures accumulat$ spontane\sly on ! "y e>?4 ,on ! o!r h&1 six billion ye>s f n[ ,u w h become s r>e t x w be impossible to get a reactor go+ by mod]ation4 ,at ! same "t ! isotope sep>ation w h become mo/ exp5sive s9ce ! isotope to be sep>at$ w be pres5t 9 an abundance ( less ?an #ajj p>ts 9 a million4 ,= ^? :o l to worry ab\t ! di/ant future we %\ld ha/5 to add t o!r me?ods ( obta9+ atomic en]gy w rema9 possible4 ,& 9 any case !re is good reason to believe t "s /ell> explosions produce fre% supplies ( ,u :i* space m]*ants c\ld und\bt$ly make available4 ,z to our pres5t t]re/rial supplies3 uranium1 l o!r heavy elem5ts1 is q r>e4 ,b ! e>? is divid$ into lay]s ( :i* ! topmo/ #aj miles1 =m+ some?+ ( a slag or scum1 conta9 q a few r>e comp\nds4 ,9 p>ticul> almo/ all ( ! uranium 9 our planet is conv5i5tly collect$ "r "u our feet1 = u to use z we see fit4 ,,*apt] ,,viii ,action ( ,radiation on ,matt] ,:5 an en]getic p>ticle moves ?r\gh matt] 7liv+ or nonliv+71 :at happ5s is a "q ( *emi/ry4 ,*emi/ry is ! subject t deals ) ! arrangem5t & re>rangem5t ( electrons 9 atoms & molecules4 ,a *emical re>rangem5t g5]ally requires an en]gy 9 ! neighborhood ( a few electron-volts4 7,z we h se51 an electron-volt is ! en]gy releas$ :5 an electron moves ?r\gh a pot5tial ( "o volt1 i4e41 a little less ?an "o p] c5t ( ! driv+ =ce 9 a /&>d electric outlet47 ,an en]getic p>ticle1 su* z might be emitt$ 9 a radioactive decay1 typically has an en]gy ( a few million electron-volts4 ,?us a s+le su* p>ticle has ! pot5tiality ( ab\t a million *emical re>rangem5ts4 ,en]getic p>ticles may be *>g$ or neutral1 light or heavy1 or electromagnetic 9 nature4 ,because ( ?is div]sity "o might ?9k !re w\ld be no common gr\nds = comp>+ ! action on matt] ( diff]5t p>ticles4 ,ea* p>ticle might conceivably make its own inimitable v>iety ( *emical re>rangem5ts4 ,actually ?is is n ! case4 ,unlike "s *emical poisons1 :i* seek out specific molecules 9 our body1 ! en]getic p>ticles /rike at :atev] atoms or molecules happ5 to get 9 _! way4 ,!y act1 9 ?is s5se1 l a sl$ge hamm]4 ,_! effects c be measur$ directly f ! /r5g? 7or en]gy7 ( ! bl[4 ,:i* p>ticle deliv]s ! bl[ is ( little consequ5ce provid$ ! same am\nt ( en]gy is deliv]$ & provid$ ! same tissues are affect$ 79 ! case ( liv+ matt]74 ,aft] ! bl[1 h[ev]1 "s specific *emical effects may occur4 ,:5 wat] or "s o!r molecule 9 ! body is brok5 up by radiation1 ! fragm5ts produc$ may !mselves be *emical poisons & attack ! biologically important l>ge molecules 9 a second>y way4 ,9 fact1 x seems probable t a consid]able "p ( ! radiation damage caus$ 9 liv+ sy/ems1 bo? heal?wise & g5etically1 occurs 9 ?is mann]4 ,al?\gh ! en]getic p>ticles are all simil> 9 _! ultimate action on matt]1 namely 9 produc+ :olesale de/ruction ( atoms & molecules1 !y diff] some:at 9 ! way 9 :i* !y br+ ab\t ?is de/ruction4 ,*>g$ p>ticles act 9 "o way1 gamma rays 9 ano!r1 & neutrons 9 /ill ano!r4 ,x is simple/ to beg9 our discussion ) ! *>g$ p>ticles4 ,! mo/ important *>g$ p>ticles are ^? connect$ ) ! natural backgr\nd ( radioactivity & cosmic rays1 & ! fission process4 ,^! include alpha rays1 beta rays1 mesons1 & fission fragm5ts4 ,= review1 a table ( ! weights & *>ges ( ^! p>ticles1 z well z a few o!rs1 is %[n4 ,z usual1 we h us$ ! weight & *>ge ( ! proton z units4 ,p>ticle ,weight ,*>ge proton #a #a alpha #d #b electron beta rays #a_/ahdj -#a positron 0 #a_/ahdj #a deut]on #b #a triton #c #a meson #a_/h #a1 -#a av]age light fission fragm5t #ig #bj av]age heavy fission fragm5t #ach #bb ,if ! fission fragm5ts 7 completely /ripp$ ( _! orbital electrons1 !y w\ld h *>ges ev5 great] ?an ! values indicat$ 9 ! table4 ,! read] w recall t ! av]age *>ge ( ! nucleus ( ! light fission fragm5t is #ch1 & ( ! heavy1 #ed4 ,b su* highly positively *>g$ p>ticles ex]t an enorm\s attraction on electrons4 ,"s ( ^! rema9 atta*$ ev5 dur+ ! fission process itself4 ,z ! fission products lose _! spe$ dur+ passage ?r\gh matt]1 !y pick up m electrons & gradually lose _! *>ge4 ,:5 any ( ^! en]getic *>g$ p>ticles moves ?r\gh matt]1 x int]acts ) electrons 9 ! atoms4 ,z a result ( ?is int]action1 ! electrons may be dislodg$ f _! usual /ates ( motion4 ,if ! int]action is g5tle--ei!r because ! *>g$ p>ticle passes ! atom at a consid]able di/ance or else because ! p>ticle is mov+ s rapidly t ! int]action la/s = only a %ort "t--! electron may be left undi/urb$4 ,if ! int]action is m viol5t1 h[ev]1 ! electron may be excit$ to a m en]getic /ate ( motion :ile /ill rema9+ 9 ! same atom or molecule2 or x may actually be eject$1 end+ up at "s o!r atomic site4 ,9 ?is latt] ev5t ! orig9al atom is left ) a residual positive *>ge & is said to be ioniz$4 ,at ! same "t ! displac$ electron is apt to unite ) :atev] atom or molecule happ5s to be ne>by1 creat+ 9 ?is way a negative ion4 ,! :ole process may be describ$ z =m+ an ion pair4 ,9 ! wake ( ! *>g$ p>ticle "o f9ds1 !re=e1 ioniz$ & excit$ atoms & molecules4 ,a re>rangem5t ( atoms w n[ ensue :i* leads to new *emical comp\nds4 ,! important ?+ = u is1 h[ev]1 t ^! *emical *anges d n dep5d v mu* on ! type ( p>ticle :i* produc$ ! ionization2 ! proportion betwe5 ionization1 excitation1 & ev5tual *emical reaction rema9s m or less ! same4 ,r\ghly speak+1 ! m ion pairs t are =m$ 9 liv+ cells1 ! great] is ! ext5t ( biological damage4 ,to make an ion pair requires ! exp5diture ( a c]ta9 am\nt ( en]gy4 ,x might seem z ?\gh ?is am\nt %\ld dep5d crucially on ! weight1 *>ge1 & en]gy ( ! p>ticle1 & also on ! m$ium ?r\gh :i* ! p>ticle is mov+4 ,?is is n s4 ,!re is "s dep5d5ce1 ( c\rse1 b only slight4 ,any *>g$ p>ticle1 irrespective ( its en]gy1 mov+ 9 any m$ium--air1 wat]1 soil1 or liv+ tissue--creates ion pairs at ! rate ( ab\t "o p] #cb electron-volts4 ,a "o-million-electron-volt p>ticle produces ab\t #cj1jjj ion pairs be=e los+ all ( its en]gy4 7,:5 x does lose its en]gy1 if x is a positively *>g$ p>ticle1 x w pick up en\gh electrons to become neutral4 ,an alpha p>ticle1 = example1 w become an ord9>y helium atom2 a proton w become an atom ( hydrog547 ,we h said t two *>g$ p>ticles hav+ ! same en]gy1 produce ! same total numb] ( ionizations4 ,!re is an important respect1 h[ev]1 9 :i* *>g$ p>ticles ( ! same en]gy may diff]4 ,t is1 9 ! d5sity ( ionization along _! pa?s4 ,9 p>ticul>1 ! m sl[ly ! p>ticle is mov+ & ! great] its *>ge1 ! m ionization & damage x w produce 9 a giv5 di/ance4 ,at ! same "t x w lose en]gy at a great] rate4 ,if we comp>e two *>g$ p>ticles ( ! same en]gy pl[+ into matt]1 ! "o :i* leaves ! deep] furr[ w be /opp$ m quickly4 ,= a great] *>ge x is easy to und]/& t ! electrical int]action is increas$ & h5ce ea* atomic electron is m /rongly di/urb$4 ,if1 on ! o!r h&1 ! p>ticle moves m sl[ly 7:i* is usually ! case if x is heavy7 x sp5ds a long] "t 9 ! neighborhood ( ! atomic electrons4 ,! electrical int]action ?us has a long] duration & is m effective 9 eject+ an electron4 ,= ?is same reason ! d5sity ( ionization along ! pa? ( a p>ticul> *>g$ p>ticle %\ld t5d to become great] & great] z ! p>ticle sl[s d[n4 ,actually ?is t5d5cy is oppos$ 9 ! case ( a fission fragm5t by ! increas$ likelihood ( ! p>ticle's pick+ up electrons & r$uc+ its *>ge4 ,z a result1 ! ionization d5sity = ^! fragm5ts is r uni=m4 ,if a heavily *>g$1 sl[ p>ticle moves ?r\gh matt] x leaves s _m di/urb$ & disrupt$ molecules beh9d t n[ ^! molecules may react ) ea* o!r4 ,!re=e heavy ionization may lead to peculi> effects4 ,nev]!less all ioniz+ p>ticles give rise to r\ghly simil> *emical *ange & de/ruction4 ,except = ! beta rays1 all ! *>g$ p>ticles are v heavy comp>$ to ! electron4 ,consequ5tly1 z !y move ?r\gh matt] & int]act ) ! atomic electrons1 _! pa?s are n p]ceptibly deflect$ f ! orig9al direction4 ,! beta rays1 on ! o!r h&1 hav+ ! same weight z ! atomic electrons1 are appreciably affect$ by _! enc\nt]s & are frequ5tly =c$ to *ange direction4 ,_! pa?s are ?us w9d+ & r&om4 ,because ! beta ray does n travel 9 a /raight l9e1 its ability to p5etrate matt] mu/ n be measur$ by its total pa? l5g?4 ,z a rule ( ?umb1 ! range ( a beta p>ticle1 be+ ! di/ance x travels along ! l9e ( its orig9al direction1 is ab\t "o half ( its total pa? l5g?4 ,= heavi] *>g$ p>ticles1 h[ev]1 no di/9ction ne$ be made betwe5 range & actual di/ance travel$4 ,! mo/ important fact ab\t ! ranges ( *>g$ p>ticles is t !y are small4 ,an alpha p>ticle1 = in/ance1 ) a typical radioactive en]gy ( a few million electron-volts1 has a range 9 wat] 7or liv+ tissue7 ( a few ?\s&?s ( an in*4 ,su* a p>ticle c\ld n p5etrate a %eet ( pap]4 ,a fission fragm5t1 despite its great en]gy1 is ev5 less p5etrat+ ?an ! alpha p>ticle4 ,! proton has a some:at great] range ?an ! alpha p>ticle4 ,b ! beta ray1 because ( its l[ weight1 has by f> ! greate/ range ( any ( ! *>g$ p>ticles4 ,ev5 x1 h[ev]1 goes only a fraction ( an in* 9 solid or liquid mat]ials4 ,! foll[+ table %[s ! ranges 79 in*es7 ( "s ( ! *>g$ p>ticles 9 air & wat] z a function ( en]gy 79 millions ( electron-volts73 ,range ,air ,wat] 7,same z liv+ tissue7 ,en]gy #e #a #b #e #e #a #b #e alpha #j4a #j4b #j4d #a4d #j4jjja #j4jjjb #j4jjjd #j4jjad proton #j4c #j4i #b4h #ac4d #j4jjje #j4jja #j4jjc #j4jad beta #di4 #acj4 #cjj4 #ggj4 #j4jfc #j4af #j4ch #a4j ,! table %[s t *>g$ p>ticles travel only %ort di/ances 9 matt]4 ,= ?is reason ^! p>ticles are n a s]i\s ext]nal radiation haz>d4 ,! protons & ! alpha rays are usually /opp$ by less ?an a foot ( air4 ,ord9>y clo?+ or ev5 ! out] lay] ( our sk9 7:i* is compos$ ( nonliv+ cells7 w /op !m completely4 ,beta rays are /opp$ by less ?an sev5ty feet ( air or an in* or less ( solid mat]ial4 7,actually mo/ ( ! beta rays produc$ 9 ! fission process h en]gies less ?an a million electron-volts or s1 & h5ce _! ranges are ev5 small]47 ,radioactive contam9ation ( beta emitt]s directly on "o's clo!s or body c\ld cause tr\ble2 b a good scrubb+ soon aft] exposure w elim9ate ?is problem4 ,! int]ior ( a h\se or build+ %\ld be q safe f any outside s\rce ( *>g$ p>ticles emitt$ by radioactive sub/ances except possibly ! mo/ en]getic beta rays4 ,only if ! s\rce ( *>g$ p>ticles is inside ! body s t 9 spite ( _! limit$ ranges ! p>ticles c f9d _! way to s5sitive tissues1 is !re any dang]4 ,9 ?is case1 z we %all see 9 a lat] *apt]1 ! dang] may be consid]able4 ,*>g$ p>ticles ( "o type /& pretty mu* by !mselves4 ,^! are ! mesons f\nd 9 cosmic rays4 ,^! p>ticles move z fa/ z en]getic beta rays &1 l ! beta rays1 c>ry unit *>ge4 ,_! biological effects are !re=e ! same z ! biological effects ( beta radiation1 ) "o important diff]5ce4 ,! cosmic ray mesons c>ry mu* m en]gy & !re=e h a mu* great] range4 ,:]eas ! beta rays are /opp$ 9 ! sk91 ! mesons c cause damage ?r\gh\t ! entire body4 ,! mesons produce ! same effects z a sub/ance :i* emits beta radiation uni=mly 9 ! :ole body4 ,?is fact is important4 ,x puts u 9 ! position to comp>e effects ( man-made radioactivity ) effects ( ! cosmic rays to :i* we are con/antly expos$4 ,n all ! en]gy 9 cosmic rays is c>ri$ by mesons4 ,we also f9d %[]s ( electrons4 ,^! are almo/ ! same z beta rays except t !y h m en]gy & arrive frequ5tly 9 fairly sizeable numb]s travel+ along ne>ly p>allel tracks4 ,_! effects1 h[ev]1 are ! same z ! effects ( ! mesons4 ,we h be5 talk+ n[ ab\t ! int]actions betwe5 *>g$ p>ticles & ! atomic electrons4 ,no m5tion has be5 made ( int]actions betwe5 ! *>g$ p>ticles & nuclei4 ,nucle> int]actions d occur sometimes1 b by & l>ge !y h only a negligible influ5ce 9 sl[+ d[n ! *>g$ p>ticle4 ,!y d affect1 h[ev]1 beta rays4 ,:5 a beta ray collides ) a highly *>g$ nucleus1 ! beta p>ticle is viol5tly deflect$4 ,! viol5ce ( ?is process is due to ! heavy *>ge ( ! nucleus & ! small mass ( ! beta p>ticle4 ,9 ! sudd5 *ange ( velocity :i* occurs1 "p ( ! electric =ce field :i* surr\nds ! electron breaks loose2 ! result is high-frequ5cy radiation call$ ,x-rays4 ,! importance ( su* electromagnetic radiation is t x c p5etrate m deeply into matt]4 ,9 our bodies1 = typical beta-ray en]gies1 only a small "p ( ! beta-ray en]gy is conv]t$ into ,x-rays4 ,b 9 _m radioactive processes gamma rays 7:i* are physically ! same z ,x-rays7 are produc$ q abundantly4 ,^! rays may c>ry z mu* or m en]gy ?an ! beta rays4 ,unlike *>g$ p>ticles1 :i* con/antly int]act z !y move ?r\gh matt]1 gamma rays c g = long di/ances )\t hav+ a s+le enc\nt]4 ,! actual di/ance dep5ds on ! en]gy ( ! gamma ray1 ! m$ium 9 :i* x moves1 & pure *ance4 ,on ! av]age1 a "o-million-volt gamma ray goes ab\t six in*es 9 wat] be=e any?+ at all happ5s to x4 ,a f\r-million-volt gamma ray goes ab\t a foot4 ,9 liv+ matt] ! di/ances are approximately ! same4 ,?us gamma rays f an ext]nal s\rce c f9d _! way deep inside ! body4 ,( c\rse liv+ matt] is n injur$ by ! m]e pres5ce ( a gamma ray4 ,!re is a small probability t ! gamma ray c\ld g "r ?r\gh ! body )\t a s+le enc\nt]4 ,if s1 !re w\ld be no biological effect4 ,an effect is produc$ only :5 ! gamma ray int]acts ) ! matt]4 ,!re are ?ree mo/ important ways 9 :i* su* an int]action may occur4 ,"o way is simple absorption ( ! gamma ray by "o ( ! atomic electrons4 ,! gamma ray disappe>s 9 ?is process1 & ! electron acquires all ( its en]gy4 ,a t9y bit ( ?is en]gy is us$ = ! electron to break its bond ) ! atom4 ,! rema9d] goes into k9etic motion ( ! electron4 ,! electron is n[ on ! loose & c cause biological damage by excit+ & ioniz+ o!r atomic electrons4 ,9 fact x is n[ ! same ?+ :i* we us$ to call a beta ray4 ,a second way 9 :i* ! gamma ray may int]act ) matt] is by scatt]+4 ,9 ?is case ! gamma ray does n disappe> b m]ely loses a "p ( its en]gy to ! atomic electron4 ,aga9 ! electron is free to cause biological damage1 :ile ! gamma ray goes on to its next enc\nt]4 ,! ?ird way requires t ! gamma ray be ne> a nucleus & h an en]gy great] ?an a million electron-volts4 7,ord9>y ,x-rays su* z are us$ 9 m$ical practice are n en]getic en\gh = ?is process to occur47 ,"u ^! conditions ! gamma ray may disappe>1 ) ! simultane\s appe>ance ( an electron & a positron4 ,?is is an example ( ! creation ( matt] out ( pure en]gy4 ,9 accordance ) ! =mula ,e mc1 a "p ( ! gamma-ray en]gy is consum$ 9 produc+ p>ticles ) def9ite masses4 ,?is am\nts to ab\t "o million electron-volts4 ,! rema9d] ( ! gamma-ray en]gy goes into k9etic motion ( ! two p>ticles4 ,aga9 biological damage results f ! subsequ5t ionization due to ! *>g$ p>ticles4 ,aft] ! positron has exp5d$ its k9etic en]gy 9 ! ionization process1 x w jo9 ) an electron 9 a disappe>+ act4 ,! en]gy reappe>s 9 ! =m ( two or ?ree gamma rays 7ea* hav+ less en]gy ?an ! orig9al gamma ray74 ,9 no case is ! gamma ray directly responsible = any biological damage4 ,! damage is always made by electrons 7or positrons7 to :i* ! gamma ray has transf]r$ "s or all ( its en]gy4 ,b ?is only makes gamma rays ! m dang]\s4 ,!y c fir/ p5etrate to ! s5sitive tissues ( ! body1 & !n cause ionization4 ,we h already m5tion$ t ,x-rays are ! same z gamma rays4 ,! latt] are produc$ by an excit$ nucleus1 ! =m] 9 ! collision ( an electron 7or a beta ray7 ) a nucleus4 ,! man-made ,x-rays are obta9$ by fir/ accel]at+ a /ream ( electrons & !n lett+ !m imp+e on a t>get conta9+ highly *>g$ nuclei4 ,! usefulness ( ,x-rays is1 ( c\rse1 due to _! p[] ( p5etration2 t is ! same prop]ty :i* r5d]s ,x-rays dang]\s4 ,"o c use ,x-rays to f9d out :at happ5s to be inside ! human body4 ,b ?is _c be done )\t produc+ "s disruption & re>rangem5t 9 ! tissues :i* lie 9 ! pa? ( ! ,x-rays4 ,! damage is ( ! same k9d z t caus$ by radioactivity or cosmic rays4 ,! effects ( neutrons on matt] are r simil> to ! effects ( gamma rays4 ,l gamma rays1 neutrons c travel long di/ances 9 matt] )\t int]act+4 ,on ! av]age1 a million-volt neutron goes a few in*es 9 wat] be=e hav+ a collision ( any k9d4 ,also l ! gamma rays1 ! neutrons are n !mselves directly responsible = any biological damage4 ,be+ neutral1 !y int]act only ) ! atomic nuclei to :i* !y are /rongly attract$4 ,by f> ! mo/ important ( ^! int]actions is ) ! nuclei ( hydrog54 ,!re are a great numb] ( ^! 9 liv+ tissue 9 ! =m ( prote9 & wat] molecules4 ,! collisions ) hydrog5 nuclei 7i4e41 protons7 are important because a l>ge fraction ( ! neutron en]gy is transf]r$ 9 ! process4 ,?is happ5s because ! neutron & ! proton h v ne>ly ! same weight4 ,if ! neutron hits a heavy nucleus1 x loses only a small fraction ( its en]gy 9 ! impact4#i ,aft] collid+ ) hydrog5 or a heavi] nucleus1 ! neutron cont9ues on to o!r su* collisions4 ,! nucleus1 h[ev]1 be+ *>g$ & en]getic1 n[ causes excitation & ionization ( atomic electrons4 ,?us1 l gamma rays1 en]getic neutrons are exce$+ly dang]\s1 because !y c fir/ p5etrate & !n cause ionization4 ,neutrons are dang]\s ev5 :5 !y are n en]getic4 ,a non5]getic neutron may react ) nuclei ( liv+ matt] 9 a numb] ( ways ( :i* two are p>ticul>ly probable4 ,ei!r ! neutron may be captur$ by a proton to =m a deut]on1 9 :i* case ! excess en]gy w be emitt$ 9 ! =m ( a two-million-volt gamma ray t w cause fur!r damage4 ,or ! neutron may react ) a nucleus ( nitrog5 7abundantly pres5t 9 liv+ matt]7 to produce a nucleus ( c>bon & an en]getic proton4 ,?us a non5]getic neutron w h a biological effect equival5t to an en]getic gamma ray1 or to an en]getic proton plus an en]getic c>bon ion4 ,9 summ>y1 all p>ticles1 *>g$ or n1 h a simil> action on matt]4 ,directly or indirectly1 !y produce excit$ atoms1 molecules1 & ion pairs4 ,^! processes always occur 9 practically ! same proportions1 & !re=e ! numb] ( ion pairs =m$ c be us$ z a measure ( ! radiation effects4 ,! m ion pairs produc$ 9 liv+ matt]1 ! great] ! ext5t ( biological damage4 ,= ?is reason x is cu/om>y to describe radiation effects 9 t]ms ( ! numb] ( ion pairs creat$ p] gram ( liv+ tissue 9 v>i\s p>ts ( ! body4 ,s9ce ea* ion pair corresponds to an en]gy transf] ( ab\t #cb electron-volts1 an alt]native description may be giv5 9 t]ms ( ! am\nt ( en]gy deposit$4 ,! unit 9 common usage = ?is purpose is ! ro5tg51 :i* means specifically an en]gy equival5t to lift+ ! body 79 :i* ! radiation is deposit$7 by "o tw5ty-fif? ( an in*4 ,?is is equival5t to ab\t #fj million million ion pairs 9 ea* ounce4 ,x is less exact b m significant to say t "o ro5tg5 deposits 9 a cell ( our body a few ?\s& ion pairs4 ,( c\rse ! am\nt ( ionization )9 individual cells is n a quantity t is easily measur$4 ,:at "o usually kn[s in/ead1 is ! ro5tg5 dosage to a piece ( tissue1 :i* consi/s ( _m cells4 ,if ! *>g$ p>ticles induc+ ! ionization are electrons 7z !y are :5 ! prim>y radiation is a beta ray or a gamma ray71 ! ionization w be di/ribut$ m or less uni=mly among ! cells 9 ! affect$ neighborhood4 ,if ! *>g$ p>ticle is heavy--a proton or an alpha ray--! d5sity ( ionization :i* x produces is mu* great]1 s t "s cells receive a good _m m ion pairs1 :ile o!rs ne>by may receive none4 ,= ?is reason x is sometimes important to specify n j h[ _m ro5tg5s ! tissue has be5 expos$ to1 b also :i* k9d ( radiation has be5 responsible4 ,9 a lat] *apt] we %all discuss ! biological effects ( v>i\s am\nts ( radiation4 ,we may m5tion "h1 h[ev]1 t #ajjj ro5tg5s ( ,x-rays or gamma rays deliv]$ m or less uni=mly ov] ! :ole body ( a human be+ 9 a "t less ?an a few h\rs or s1 w lead to almo/ c]ta9 dea?4 ,& x is a rem>kable fact t nature has n provid$ u ) a w>n+4 ,radiation does n hurt4 ,! great] is ! ne$ t we und]/& ?is process :i* affects our well-be+ b n our s5ses4 ,,*apt] ,,ix ,! ,te/ ,te/+ ( atomic explosives is usually c>ri$ out 9 beautiful surr\nd+s4 ,!re is a good reason = ?is3 ! radioactive fall\t4 ,because ( ! fall\t1 ! te/ site mu/ be isolat$4 ,! pres5ce ( human population does n improve nature 7) exceptions :i* are q r>e & ! m notable74 ,also1 to keep ! site clean1 te/s mu/ be c>ri$ out 9 ! abs5ce ( ra94 ,!re=e1 at ! site "o usually f9ds sun%9e & solitude4 ,= ! p>ticipants ! beauty ( nature =ms ! back-drop to prep>ations ( exp]im5ts :i* are difficult & excit+ to ev]yone involv$4 ,at ! end1 ! atomic explosion is always dw>f$ by its sett+4 ,b ! "w t culm9ates 9 ! detonation is rew>d$ by some?+ q diff]5t f a fla% & a bang4 ,! really important results ( a te/ consi/ 9 m>ks on photographic plates4 ,mo/ ( ! app>atus t produc$ ! plates has be5 de/roy$ 9 ! explosion4 ,b en\gh is sav$ s t "o c conclude :at has happ5$ 9 ! %ort fractions ( a second t pass betwe5 ! press+ ( ! button & ! k 9 ! obs]v]3 ?is 0 x4 ,9 ^? fractions ( a second ano!r /one 0 add$ to ! /ructure :i* we may call a/rophysical eng9e]+4 ,:at happ5s & :at is obs]v$ 9 nucle> explosions are closely relat$ to ! behavior ( matt] 9 ! int]iors ( ! />s4 ,! details ( ! nucle> explosion _c be describ$ "h = ?ree reasons4 ,fir/1 ! details are secret4 ,second1 ! size ( ?is book & ! =be>ance ( ! read] set limitations4 ,& ?ird1 we und]/& only a small "p ( ! process4 ,)9 ^! limitations1 ?is is :at happ5s3 ,! actual nucle> reaction takes only a fraction ( a microsecond 7"o microsecond "o million? ( a second74 ,all ! en]gy ( ! bomb is releas$ 9 ?is %ort p]iod4 ,at ! end ( ?is p]iod1 ! ma9 body ( ! nucle> mat]ial is mov+ ap>t at a rapid rate & by ?is motion fur!r nucle> reactions are /opp$4 ,9 addition to ! m or less ord]ly outw>d motion1 consid]able portions ( ! en]gy are f\nd 9 ! disord]ly temp]ature motion1 :i* has /ripp$ mo/ ( ! electrons (f ! nuclei & has trans=m$ ! atoms into a freely & *aotically mov+ assembly ( *>g$ p>ticles4 ,by ?is "t _m ( ! orig9al nuclei h be5 trans=m$ into nuclei ( radioactive species1 p>tly by ! fission process & p>tly by ! capture ( neutrons 9 all sorts ( atoms :i* _h be5 orig9ally pres5t 9 ! bomb mat]ials4 ,/ill ano!r portion ( ! en]gy is pres5t z electromagnetic radiation4 ,?is radiation closely resembles light except t x is ( %ort] wave l5g? & is !re=e n actually visible2 b x c be absorb$ & re-emitt$ by all sorts ( mat]ials1 & is 9 a viol5t ex*ange ( en]gy ) ! explod$ bomb fragm5ts4 ,all ?is p]turbation spreads outw>d f ! region :]e ! nucle> reaction has tak5 place into ! surr\nd+ compon5ts ( ! bomb4 ,dur+ ! outw>d spread1 m atoms & m space get engulf$4 ,! agitation & ! radiation become some:at less hot4 ,?is hot region t5ds to be limit$ by a %>ply def9$ b\nd>y :i* is call$ a %ock front & :i* is mov+ outw>d at a spe$ ( sev]al hundr$ miles p] second4 ,?is front f9ally rea*es ! limits ( ! m or less d5se mat]ial 9 :i* ! :ole bomb /ructure 0 orig9ally encas$4 ,x !n breaks ?r\gh into ! surr\nd+ air4 ,! air heats up 9 ! imm$iate vic9ity1 & ?is is ! beg9n+ ( ! fireball4 ,f ?is po9t on1 ! en]gy spreads due to ! pu% ( ! high-temp]ature air4 ,a %>p %ock front =ms & keeps mov+ outw>d at a spe$ greatly surpass+ ord9>y s\nd spe$4 ,! radioactive mat]ial is conta9$ )9 ?is hot & exp&+ sph]e4 ,z ! fireball exp&s & ! temp]ature falls1 m & m visible radiation is emitt$4 ,actually1 ! surface is gr[+ less brilliant z ! /ructure exp&s & cools1 b its great] size & ! long] "t t is available = ! emission ( radiation ov]come ?is disadvantage4 ,f9ally1 at a radius ( p]haps a few hundr$ feet = a small bomb & a mile = a big "o1 ! fireball expansion halts4 ,?is happ5s because ! %ock front is no long] /rong en\gh to make ! air lum9\s4 ,! lum9osity n only /ops advanc+ b is actually p>tly dimm$ by absorb+ sub/ances =m$ by ! badly mi/reat$ air molecules4 ,! "t :i* has elaps$ to rea* ?is /age ( ! explosion dep5ds on ! bomb en]gy4 ,if two explosions are comp>$1 & ! bigg] "o has a ?\s& times ! explosive p[] ( ! small] "o1 !n ! "t ne$$ to rea* ! extreme expansion ( ! fireball w be approximately t5 times great] = ! m viol5t ev5t4 ,9 any case1 a reasonably close obs]v] has to use /rongly absorb+ glasses dur+ ?is "t if he is n to be bl9d$4 ,= small bombs1 ! expansion ( ! fireball is too %ort to regi/]4 ,= ! really big ones1 y c see ! expansion develop+ & y wond] :5 x w /op4 ,to ! unprotect$ eye ! small bombs are almo/ z dang]\s z ! big ones1 because !re is n en\gh "t to bl9k4 ,9 ! meantime1 ! %ock wave1 n[ sep>at$ f ! fireball1 travels ?r\gh ! air & c>ries ) x a consid]able fraction ( ! orig9al explosive p[]4 ,an important "p ( ! damage :i* a bomb c cause is due to ?is invisible pressure wave :i* spreads ) a spe$ close to t ( s\nd1 ov] a di/ance ( miles1 be=e x settles d[n into h>mless rumbl+4 ,! re/ ( ! en]gy is /ill sitt+ 9 ! fireball ne> ! po9t :]e ! explosion occurr$ & ! hot air n[ comm5ces to asc5d1 break+ up into a turbul5t mu%room z x goes4 ,! hot int]ior portions get occasionally expos$ & ! object gives ! appe>ance ( an enorm\s flam+ mass1 at lea/ :5 se5 9 a motion picture :i* sl[s d[n ! action & r$uces ! size4 ,! radiant tongues are too big & too fa/ = any ord9>y flames4 ,dur+ ?is /age ! display gradually pales suffici5tly s t x c be view$ ) ! nak$ eye4 ,! orig9ally hot masses h n[ emitt$ en\gh en]gy 9 ! =m ( light & mix$ ) a suffici5tly great mass ( cool air t !y no long] gl[ viol5tly4 ,?is mass ( c5tral & ris+ gas conta9s practically all ! radioactivity1 n only t orig9ally =m$ 9 ! explosion b also "s produc$ by neutrons :i* leak$ out ( ! bomb & got captur$ by a v>iety ( nuclei 9 ! air1 wat]1 or gr\nd )9 ! neighborhood4 ,& n[ ! aft]ma? ( ! explosion is turn+ into a display gr[+ rapidly & yet 9 a measur$ mann] s t n only ! eye ( ! obs]v] b 8 m9d & 8 feel+s c foll[ ! ev5ts4 ,! mu%room :i* has be5 =m$ by ! fir/ updraft develops into a column ) m & m agitat$ boil+ masses add$ on ! top & ) slant+ skirts ( a sn[y appe>ance desc5d+ t[>d ! sides4 ,:at is ?is :ite mass t looks j l a cl\d ( peculi> %ape & t has gr[n up to ! high heav5s 7or z ! meteorologi/s call x3 ! /ratosph]e7 9 a few m9utes be=e our eyes8 ,x is actually a cl\d3 a collection ( droplets ( wat] too small to turn into ra9 b big en\gh to reflect ! :ite light ( ! sun4 ,& x is =m$ 9 a simil> way to ! cumulus cl\ds ( a ?und]/orm4 ,inde$ x is a beautiful example ( a _m-/ori$ ca/le ( cumulus ^u cumulus4 ,b /rangely en\gh :at makes ?is cl\d is n ! heat ( ! bomb4 ,x is ! cool+ ( ! air masses t h be5 suck$ 9 z ! remnants ( ! fireball ru% upw>d l a giant balloon4 ,"u ?is balloon air is drawn upw>d4 ,z ?is air rises1 x cools & wat] vapor conta9$ 9 x cond5ses into droplets3 precisely ! same me*anism :i* gives rise to ?und]heads on a hot summ] day4 ,! :ite skirts 7:i* are n always pres5t7 d n consi/ ( any mat]ial t is fall+ out ( ! cl\d4 ,on ! contr>y1 a moi/ lay] ( air is suck$ up into ! cl\d f ! side & ! droplets :i* =m 9 ?is lay] give rise to a cl\d-%eet ) ! appe>ance ( a skirt4 ,9 big bombs ne> ! top a p>ticul>ly smoo? & :ite cap is se54 ,?is is aga9 cond5sation1 n into droplets b into f9e cry/als ( ice4 ,9 "s explosions m ?an "o ( ^! caps are pres5t4 ,f9ally ! cl\d has ga9$ its full height4 ,dep5d+ on ! size ( ! bomb x may h gr[n to #bj1jjj feet1 to #ajj1jjj feet or m4 ,!n ! w9d bl[+ at v>i\s levels 9 v>i\s directions te>s ! /ructure ap>t sweep+ "s ( x to ! ea/1 "s to ! we/4 ,! radioactive debris 9 ! cl\d has />t$ on its travel4 ,:at ?is radioactivity w d1 h[ x c affect liv+ be+s1 h[ dang]\s x actually is1 we %all discuss 9 succe$+ *apt]s4 ,b "o ?+ is cle> & rema9s pres5t 9 ! m9ds ( all p>ticipants 9 an atomic te/3 ,! dang] ( ! te/ is no?+ comp>$ to ! cata/rophe t may occur if great numb]s ( ^! weapons %\ld be us$ 9 an unre/rict$ nucle> w>4 ,x has be5 frequ5tly ass]t$ t our pres5t atomic explosives c wipe out ! cities & indu/ries ( ! greate/ c\ntries4 ,:y cont9ue ) fur!r developm5t & te/+8 ,! answ] is simple3 ,! ma9 purpose ( a w> is n to de/roy ! enemy's civilian c5t]s b r to defeat 8 arm$ =ces1 & = ?is purpose we ne$ flexible ref9$ weapons ( all k9ds & sizes4 ,we also ne$ weapons ) :i* to def5d our own cities4 ,we ne$ weapons ) :i* to def5d our allies & 9 p>ticul> we ne$ weapons :i* w d _! job aga9/ an aggressor & w d ! lea/ possible damage to ! innoc5t by/&]4 ,9 ?is la/ respect1 9 p>ticul>1 notable progress has be5 made4 ,we are develop+ clean weapons :i* are effective by _! bla/ & _! heat1 b :i* produce little radioactivity4 ,( c\rse1 bla/ & heat w d damage only ne> ! po9t ( detonation4 ,radioactivity may be c>ri$ by ! w9ds & escape ! control ( man to a consid]able ext5t4 ,x is cle> t w> is & always has be5 t]rible4 ,we refuse to believe t w>s w always be ) u b we _c disreg>d ! dang] ( w> z long z ! _w is half free & half slave4 ,an atomic w>1 limit$ or ev5 unlimit$1 ne$ n be connect$ ) m suff]+ ?an pa/ w>s4 ,h[ev]1 su* a w> w\ld probably be m viol5t & x w\ld be %ort]4 ,! /ory is told t a w> :i* turn$ out to be p]haps ! mo/ dreadful 9 ! hi/ory ( mank9d 0 />t$ ) ?is message3 8,?\ ha/ *os5 w>4 ,t w happ5 :i* w happ5 & :at is to be we "k n4 ,god alone kn[s40 ,p]haps ! only possible pa? = a free p is to be well prep>$ = w> b nev] to *oose w> z long z ! *oice is free4 ,b :at w happ5 ,god alone kn[s4 ,,*apt] ,x ,! ,radioactive ,cl\d ,9 ,febru>y #aied prep>ations 7 made on ,bik9i ,atoll = ! explosion ( a hydrog5 bomb4 ,m>* #a 0 ! 8ready0 date4 ,x did n seem probable t ! %ot w\ld actually be fir$ on t date because ! %ot c\ld be fir$ only "u q favorable w9d conditions4 ,l>ge am\nts ( radioactivity1 especially fission products1 7 expect$ f ! explosion4 ,! %ot c\ld be fir$ only if no inhabit$ places lay 9 ! d[nw9d direction4 ,bik9i is an oval-%ap$ coral reef1 an atoll4 ,x is "o ( sev]al su* atolls belong+ to ! gr\p call$ ! ,m>%all ,isl&s4 ,if y look at ! map1 y w see t we/ ( ,bik9i at a di/ance ( #bjj miles lies ,eniwetok1 on :i* our p 7 mak+ prep>ations = fur!r te/s4 ,to ! ea/ ( ,bik9i1 a hundr$ miles or s1 is ,rongelap ,atoll4 ,at t "t #fd p 7 liv+ !re4 ,!y liv$ primitively 9 palm h\ses on ! s\!rn "p ( ! atoll4 ,! nor!rn "p 0 un9habit$4 ,on ne>by ,ail+9ae ,atoll #ah ( ! ,m>%allese isl&]s 7 on a fi%+ exp$ition1 :ile f>!r to ! ea/ on ,rong]ik #bh ,am]ican s]vicem5 7 /ation$4 ,! s]vicem5 liv$ & work$ 9 alum9um huts4 ,_! ma9 job 0 to collect wea!r data4 ,illu/ration3 ,map ( ! ,m>%all ,isl&s ,mu* f>!r to ! ea/1 #cjj miles f ,bik9i1 is ,utirik4 ,"o hundr$ & fifty-sev5 ,m>%allese p liv$ on ?is atoll4 ,e>ly on ! morn+ ( ,m>* #a1 a ,japanese fi%+ boat lay some:]e to ! nor? ( ,rongelap4 ,h] "n 0 ,fukuryu ,m>u1 :i* means 9 ,engli% ! ,=tunate ,dragon4 ,!re 7 #bc m5 on bo>d4 ,actually %e 0 9 a patroll$ zone b _h n be5 sight$ by ! patrol aircraft4 ,op]ations = ! te/ 7 be+ direct$ f %ips ( ,jo9t ,task ,=ce #g4 ,= sev]al days prior to ! morn+ ( ,m>* #a1 ! wea!rm5 _h be5 mapp+ ! w9ds4 ,a w9d to ! we/ w\ld be bad = ,eniwetok4 ,a w9d to ! ea/ might hurt ,rongelap & ,rong]ik4 ,a w9d to ! s\? c\ld affect ,kwajale94 ,! ideal direction w\ld h be5 due nor?1 b ?is probably w\ld n happ5 = mon?s4 ,on 8%ot0 morn+ ! w9d 0 bl[+ to ! nor!a/4 ,! meteorologi/s gave _! 8,o4,k40 ,x 0 at dawn1 ! fir/ ( ,m>*1 #aied4 ,! fir+ crew ( n9e p l$ by a man ( consid]able exp]i5ce1 ,jack ,cl>k1 7 responsible = ! f9al arrangem5ts4 ,!y 7 9 a blockh\se on ! s\? side ( ! atoll #bj miles f ! bomb4 ,o!rs1 m ?an #ajjj p1 wat*$ f %ipbo>d "u ! direction ( ,al ,graves1 :o 0 responsible = ! te*nical phases ( ! op]ation4 ,! %ips lay s\? & a little ea/ ( ,bik9i4 ,! fir+ me*anism 0 set into op]ation 9 ! blockh\se4 ,"o aft] ano!r signals indicat$ t ! v>i\s exp]im5ts & obs]vations 7 set to "w4 ,f9ally a r$ light w5t (f & a gre5 light appe>$ on ! panel4 ,?is meant t ! bomb _h be5 detonat$4 ,! m5 on %ipbo>d wat*$ ! enorm\s fireball ?r\gh d>k5$ glasses4 ,! fir+ crew1 seal$ (f 9 ! blockh\se1 saw no?+4 ,a c\ple ( long seconds & ,graves' voice ann\nc$ ov] _! radio3 8,x 0 a good %ot40 ,a quick e/imate indicat$ #ae megatons4 ,"s m sl[ seconds & ! expect$ gr\nd %ock arriv$4 ,x 0 l a big e>?quake4 ,a bad mom5t pass$4 ,! blockh\se rock$ b held4 ,ano!r m9ute or s & ! air %ock pass$ ov]4 ,"o c\ld he> ! h+es groan--b ?is 0 no long] fright5+4 ,w\ld ! wat] wave p\r ov] ! blockh\se8 ,ev]y?+ 0 wat]tight4 ,aft] fifte5 m9utes a por?ole 0 op5$--no wat] came 94 ,! m5 9 ! blockh\se em]g$ to look at ! drift+ atomic cl\d4 ,:ile !y wat*$1 ,jack ,cl>k's radiation in/rum5t began to %[ a read+4 ,! fir+ crew 0 call$ back into ! blockh\se4 ,!re1 9 ! l[e/ corn] %ield$ by a consid]able am\nt ( s&1 !y 7 safe4 ,outside1 ! evaporat$ & cond5s+ coral came d[n 9 pellets c>ry+ m & m radioactivity4 ,9 ! meantime !re 0 fall\t on ! %ips too4 ,! w9d _h def9itely ve]$ aft] %ot "t4 ,quickly ! activity 0 wa%$ d[n4 ,no "o got a dang]\s exposure4 ,b x 0 wis] to sail away4 ,a message 0 s5t to ! blockh\se3 8,we w come back = y 9 ! ev5+40 ,aft] a little m ?an an h\r ! activity ar\nd ! blockh\se />t$ sl[ly to decrease4 ,! fir+ crew wait$ pati5tly inside )\t communication1 )\t light = ! re/ ( ! day4 ,f9ally ! %ips came back4 ,at sund[n a helicopt] w5t out to ! isl& us+ ! la/ ( daylight & all[+ z mu* "t z possible = ! activity to decay4 ,cl>k & 8 fri5ds ru%$ out ( ! blockh\se wrapp$ 9 %eets to /op ! beta rays & keep (f ! radioactive du/4 ,!y mov$ z fa/ z possible to avoid unnecess>y exposure4 ,x 0 a h>d exp]i5ce b !y got no m ?an two ro5tg5s--no m reason to worry ?an if !y _h _h a m$ical ,x-ray4 ,t[>d ! ea/1 h[ev]1 "s p 7 9 real tr\ble4 ,six or sev5 h\rs aft] ! %ot ! ,am]ican s]vicem5 on ,rong]ik notic$ a mi/like fall\t ( highly radioactive du/4 ,! w9d _h ve]$ en\gh to c>ry ! atomic cl\d ov] ! occupi$ isl&s ( ,ail+9ae1 ,rongelap1 & ,rong]ik4 ,9 ! anxi\s h\rs :i* foll[$ no "o c\ld say h[ mu* damage _h be5 done4 ,! ,am]icans on ,rong]ik _h _h "s education 9 ! dang]s ( radioactivity4 ,!y wa%$ !mselves1 put on extra clo!s1 & rema9$ inside ( ! alum9um huts z mu* z possible4 ,^! actions help$ to protect !m aga9/ beta ray burns on ! sk94 ,! ,m>%allese on ,rongelap & ,ail+9ae knew no?+ ( ! dang] & took no precautions4 ,_m ( !m suff]$ q sev]e sk9 burns4 ,all ( ! expos$ p]sons 7 evacuat$ to ,kwajale9 z soon z ! ,task ,=ce facilities w\ld p]mit4 ,b x 0 n until a week or s aft] ! explosion t arrangem5ts c\ld be made = m5 ) radiation measur+ in/rum5ts to t\r ! atolls & det]m9e :at ! levels ( exposure _h be54 ,on ! s\!rn tip ( ,rong]ik !y measur$ ! activity & calculat$ t ! ,am]ican s]vicem5 _h receiv$ approximately #gh ro5tg5s4 ,?is 0 good news because a dosage ( #ej to #ajj ro5tg5s is n le?al & only 9 r>e cases leads to any sickness4 ,9 any ev5t full recov]y c\ld be expect$ )9 a few days4 ,z !y pr[l$ ar\nd ,rong]ik atoll1 ! measur+ crew f\nd places :]e ! radiation levels _h be5 mu* high]4 ,at ! nor!rn end a p]son w\ld h receiv$ m ?an #bjj ro5tg5s4 ,on ,ail+9ae ! measur$ values 7 comp>able to ^? on ,rong]ik4 ,! e/imat$ dosage to ! ,ail+9ae p 0 #fi ro5tg5s4 ,on ,rongelap ! situation 0 mu* worse4 ,measurem5ts 9 ! s\!rn "p ( ! atoll %[$ t ! ,rongelap p _h gott5 a dose ( ab\t #age ro5tg5s4 ,su* a dose w\ld n be fatal1 b at lea/ "s ( ! p w\ld probably be sick4 ,! crew !n w5t on to explore ! re/ ( ! atoll4 ,z !y mov$ nor?1 ! dose levels rose high] & high]4 ,9 ! middle ( ! atoll1 only t5 or fifte5 miles f ! inhabit$ "p1 a p]son w\ld h receiv$ #djj ro5tg5s ( radiation4 ,at ?is level he w\ld h a fifty-fifty *ance ( surviv+4 ,on ! nor!rn tip ( ! atoll1 ab\t ?irty miles away1 ! dose w\ld h be5 ov] a ?\s& ro5tg5s4 ,su* a dose means c]ta9 dea? 9 less ?an a mon?4 ,! foll[+ table conta9s a summ>y ( :at happ5$3 ,numb] ,"t ( ,"t ( ,dose ( fall\t evacuation 7ro5tg5s7 p]sons aft] aft] %ot %ot 7h\rs7 7h\rs7 ,rongelap #fd #d to #f #ea #age ,ail+9ae #ah #d to #f #eh #fi ,rong]ik #bh #g #cb #gh ,utirik #aeg #bb #fe #ad ,=tunate ,dragon #bc #d #bjj ,on ,kwajale9 ! ,m>%allese 7 c>$ = & und]w5t m$ical obs]vation4 ,z soon z possible _! sk9 & hair 7 scrubb$ ) soap & wat]4 ,! coconut oil 9 _! hair made decontam9ation difficult4 ,dur+ all ?is "t ! pres5ce ( ! ,japanese fi%+ boat 9 ! area 0 n ev5 suspect$4 ,n until two weeks aft] ! explosion1 :5 ! little boat return$ to ,yaizu h>bor1 did ! _w f9d out4 ,by ?is "t ! #bc fi%]m5 7 pretty sick4 ,we d n "k precisely :at dose ! fi%]m5 receiv$1 b ! be/ guess is ab\t #bjj ro5tg5s4 ,unhappily1 "o ( ! fi%]m5 di$1 presumably f complications associat$ ) ! exposure to radiation4#aj ,! o!r #bb1 h[ev]1 are 9 good heal? & back at "w4 ,our m$ical in=mation on ! ,m>%allese isl&]s is complete4 ,aft] /ay+ ?ree mon?s on ,kwajale9 !y 7 remov$ to ,majuro atoll1 :]e homes 7 built = !m & :]e !y h be5 c>$ = & "u cont9u\s surveillance s9ce ! incid5t4 ,frequ5t & ?or\gh m$ical exam9ations h be5 conduct$1 h&icapp$ some:at by ! problem ( communicat+ ?r\gh an int]pret]4 ,9 ! fir/ tw5ty-f\r h\rs "s ( ! victims compla9$ ( nausea1 fev]1 & /oma*-a*e4 ,b ^! symptoms abat$ promptly 9 e case )\t treatm5t4 ,!re 0 also "s compla9t ( sk9 it*+ & a burn+ s5sation1 b ^! symptoms also la/$ only a c\ple ( days4 ,!n foll[$ a week or s ( com=t & no compla9t4 ,aft] t sk9 lesions & loss ( hair began to occur4 ,fifty to eighty p] c5t ( ! beta rays dur+ ! exposure p]iod _h an av]age en]gy ( #j4c million electron-volts4 ,mu* ( ?is en]gy 0 /opp$ 9 ! out] lay] ( sk91 :i* is two ?\s&?s ( an in* ?ick4 ,! rema9d] ( ! beta rays _h an av]age en]gy ( #j4f million electron-volts2 ^! beta rays c\ld easily p5etrate into ! deep] lay] ( live sk94 ,! mo/ important fact1 h[ev]1 0 t clo?+ ( any k9d1 ev5 a ?9 cotton fabric1 provid$ protection aga9/ all ! beta rays4 ,lesions develop$ only on ! expos$ p>ts ( ! body & 9 a few o!r places su* z ! armpits & ! creases ( ! neck :]e mat]ial t5ds to accumulate4 ,b>e feet 7 especially bad4 ,dur+ ! acute p]iod "s ( ! p walk$ on _! heels4 ,at ! end ( six mon?s lo/ hair _h gr[n out aga9 unalt]$ 9 texture & color1 & ! sk9 lesions _h heal$4 ,ev]yone appe>$ heal?y & normal ) no app>5t aft] effects4 ,!re _h be5 f\r pregnancies among/ ,rongelap wom5 at ! "t ( ! exposure4 ,"o baby 0 born dead1 b ! o!r ?ree 7 q normal4 ,!re 0 no evid5ce t ! /illbir? _h be5 due to radiation effects4 ,9 fact ! p]c5tage ( /illbir?s among/ ! ,rongelapese is normally high4 ,/ati/ically1 "o 9 f\r is n an unusual ratio4 ,today1 m ?an ?ree ye>s s9ce ! accid5t1 all ( ! ,m>%allese & ,am]ican victims seem to be fully recov]$4 ,no malignancies or leukemias h %[n up1 b ^! long-t]m effects are /ill be+ c>efully wat*$ = by an ,,aec m$ical gr\p4 ,all 9 all "s s]i\s b limit$ h>m has be5 done4 ,x 0 a close %ave4 ,to see h[ close1 "o only ne$s to glance at ! map bel[1 :i* %[s ! ro5tg5 dosage = #dh h\rs ( exposure4 ,at ! s\!rn tip ( ,rongelap1 :]e ! inhabitants liv$1 ! dosage 0 #age ro5tg5s4 ,b at ! nor!rn tip1 less ?an ?irty miles away1 ! dosage 0 m ?an a ?\s& ro5tg5s4 ,if ! w9d _h ve]$ j a little bit f>!r to ! s\?1 probably all ( ! p on ,ail+9ae1 ,rongelap1 & ,rong]ik w\ld h be5 kill$4 ,illu/ration3 ,dosage 9 ,fir/ #dh ,h\rs ,aft] ,fall\t ,began ,?is %ot prov$ :at _h be5 argu$ = _m ye>s3 t radioactivity is n j an incid5tal "p ( an atomic explosion4 ,! p on ,rongelap 7 f> outside ! area ( dang] f bla/ & !rmal effects4 ,b !y receiv$ a sizeable dose ( radiation4 ,9 fact1 a p]son c\ld h /ood unprotect$ at a di/ance ( ?irty miles f ! explosion & be5 p]fectly safe f ! bla/ & !rmal radiation4 ,b at t same di/ance 9 a d[nw9d direction he w\ld h accumulat$ a le?al dose ( radiation )9 a matt] ( m9utes aft] ! fall\t began4 ,because ( ! radioactive fall\t1 ! te/ sites mu/ be locat$ 9 remote p>ts ( ! _w4 ,x w\ld be desirable if sites c\ld be f\nd :i* are s remote f popul\s areas t ! te/s c\ld be conduct$ )\t reg>d to ! direction ( ! w9ds4 ,un=tunately ! bombs are too big & ! planet is too small4 ,z a result ! w9ds mu/ be wat*$ be=e e te/2 & ! te/s mu/ be delay$ until ! w9ds are favorable4 ,:at happ5$ to ! ,m>%allese 0 an accid5t :i* might h be5 avoid$ if ! w9ds _h be5 bl[+ m directly t[>d ! nor? at %ot "t4 ,s9ce ?is accid5t ! w9d requirem5ts = ! te/s h become f> m /r+5t1 our k ( ! dang] has increas$1 & ! rules ( safety h 9 all respects improv$4 ,_m l>ge yield weapons h be5 te/$ s9ce ,m>* #a1 #aied1 b no o!r accid5ts h occurr$4 ,we c be confid5t t accid5ts ( ?is k9d are n[ v improbable4 ,at ! ,u4 ,s4 te/ site 9 ,nevada !re has be5 no in/ance ( a major fall\t on a populat$ area4 ,probably ! mo/ worrisome situation :i* has occurr$ !re 0 9 ! spr+ ( #aiec dur+ ! ,up%ot-,kno?ole te/ s]ies4 ,aft] ! n9? %ot ( ! s]ies ! cl\d drift$ ea/w>d ov] ,/4 ,george1 ,utah1 a t[n ( ab\t #ejjj p4 ,"s fall\t occurr$ %ortly be=e n9e o'clock 9 ! morn+4 ,ab\t n9e-?irty ,,aec (ficials issu$ a w>n+ advis+ ! resid5ts to /ay indoors4 ,by noon ! w>n+ 0 )drawn & p 7 all[$ to cont9ue ) _! normal affairs4 ,! incid5t left ev]yone a little bit sc>$1 b no "o _h receiv$ a radiation dose great] ?an two or ?ree ro5tg5s4 ,we h be5 talk+ ab\t ! local fall\t :i* occurs )9 a few hundr$ miles ( ! te/ site4 ,n all ! radioactivity :i* is made 9 ! explosion goes into ?is fall\t4 ,"s ( x travels = really long di/ances1 n hundr$s b actually ?\s&s ( miles f gr\nd z]o4 ,?is "p ( ! radioactivity is dissem9at$ _w-wide & completely escapes ! control ( man4 ,to be sure1 by ! "t ?is radioactivity is di/ribut$ ov] a l>ge fraction ( ! e>?'s surface1 ! dosage levels ( radiation are v t9y1 less ?an a t5 ?\s&? ( a ro5tg5 = a megaton explosion4 ,!re is no dang] :atev] t a p]son w\ld die or ev5 become mildly sick f ?is am\nt ( radiation4 ,!re is1 h[ev]1 ! possibility ( long-range effects su* z bone canc]1 leukemia1 & g5etic mutation4 ,! _w-wide dang] is1 ( c\rse1 prim>ily due to ! big bombs4 ,! little ones1 su* z are te/$ 9 ,nevada1 release ab\t t5 kilotons 7,,tnt equival5t7 ( fission en]gy4 ,"s ( ! big ones 9 ! ,pacific release a few megatons ( fission en]gy4 ,s9ce ! am\nt ( radioactivity is proportional to ! fission en]gy releas$1 "o big bomb is equival5t to sev]al hundr$ or possibly a ?\s& little ones4 ,altoge!r 9 ,nevada1 to date1 !re h be5 only sixty or sev5ty %ots4 ,x may be desirable to m9imize ! _w-wide fall\t f ! big %ots 9 ! ,pacific4 ,b = ! little %ots 9 ,nevada1 x is probably m important to m9imize ! local fall\t4 ,h[ mu* radioactivity goes into ! local fall\t1 h[ mu* into ! _w-wide1 & h[ ^! relative am\nts c be controll$1 are ! ma9 topics = ! rema9d] ( ?is *apt]4 ,n all ! radioactivity :i* is made 9 ! explosion contributes to ! fall\t1 ei!r local or _w-wide4 ,"s ( ! radioactive fission fragm5ts 7gamma emitt]s7 h su* %ort half-lives#aa t !y actually dis9tegrate be=e ! bomb has disassembl$4 ,a great _m o!rs dis9tegrate 9 ! fir/ few m9utes :ile ! atomic cl\d is ris+4 ,! en]getic beta & gamma rays releas$ 9 ^! e>ly1 rapid dis9tegrations are /opp$ 9 %ort di/ances & m]ely add to ! havoc at ! sc5e ( ! explosion4 ,illu/ration3 ,,usaec--,jo9t ,(fice ( ,te/ ,in=mation #a4 ,a %all[ und]gr\nd explosion4 ,! radioactivity & ! gr\nd dirt are ?or\ghly mix$4 ,illu/ration3 ,,usaec--,look\t ,m\nta9 ,laboratory1 ,,usaf #b4 ,an atomic te/ t[]--five hundr$ feet high4 ,illu/ration3 ,,usaec #c4 ,a t[] %ot4 ,gr\nd dirt rises along ! /em1 b v little actually mixes ) ! fireball4 ,illu/ration3 ,elton ,p4 ,"l--,,usaec #d4 ,an air %ot--#c1ejj feet above gr\nd4 ,no dirt4 ,illu/ration3 #e4 ,leg bone ( a ?ree-mon?-old rabbit kill$ t5 m9utes aft] injection ( ,sr4 ,! d>k5$ areas %[ :]e ! /rontium has be5 deposit$4 ,sr & normal ,sr w\ld be deposit$ 9 ! same places4 ,x is an important fact t ! deposition is fairly uni=m 9 ! calcifi$ portions ( ! bone4 ,f a *apt] by ,vaughan1 ,tutt1 & ,kidman 9 ! book ,biological ,haz>ds ( ,atomic ,en]gy1 edit$ by ,hadd[1 publi%$ by ,ox=d ,univ]sity ,press1 #aieb ,illu/ration3 #f4 ,leg bone ( a woman :o di$ ( radium poison+4 ,! bright regions %[ :]e ! radium has be5 deposit$4 ,hot spots are cle>ly visible4 ,f an article1 8,! ,late ,effects ( ,int]nally ,deposit$ ,radioactive ,mat]ials 9 ,man10 by ,aub et al41 9 ,m$ic9e--a pr(essional j\rnal1 ,vol4 #ca1 ,no4 #c1 ,septemb]1 #aieb ,illu/ration3 ,,usaec--,knolls ,atomic ,p[] ,laboratory #g4 ,capsules ( cobalt1 %ield$ 9 a wat] tank4 ,"o hundr$ & ?irty million doll>s' wor? ( radium1 twice ! _w's pres5t supply1 w\ld be ne$$ to equal ! rays f ?is p[]ful gamma s\rce4 ,illu/ration3 ,,usaec #h4 ,cobalt irradiation4 ,illu/ration3 #a4 ,! metallic elem5t cobalt is ma*9$ into waf]s slightly l>g] ?an a dime4 ,illu/ration3 #b4 ,! waf]s are plac$ edge to edge 9 alum9um conta9]s1 !n ins]t$ into an atomic furnace1 or reactor4 ,illu/ration3 #c4 ,"u bomb>dm5t ( neutrons1 ! nuclei ( ! cobalt atoms become excit$ & emit radiation1 or rays4 ,illu/ration3 #d4 ,aft] 8cook+0 9 ! reactor a c]ta9 "t1 ! cobalt is remov$ & plac$ 9 %ield$ conta9]s = %ipm5t4 ,illu/ration3 #e4 ,! n[ radioactive cobalt goes f ! ,savannah ,riv] ,plant to ,oak ,ridge = re-%ipm5t to m$ical c5t]s all ov] ! c\ntry4 ,illu/ration3 #f4 ,at m$ical c5t]s1 x is plac$ 9 tele-!rapy ma*9es4 ,its p[]ful rays aid m$ical speciali/s 9 ! fight aga9/ canc]4 ,illu/ration3 ,,nto--,look\t ,m\nta9 ,laboratory ,photo #i4 ,! smoke-r+ cl\d f ! air-def5se atomic weapon4 ,illu/ration3 ,wide ,_w ,photo #aj4 ,illu/ration3 ,univ]sity ( ,cali=nia ,radiation ,laboratory #aa4 ,! /reaks are cond5sation trails produc$ by *>g$ p>ticles 9 a ,wilson ,cl\d ,*amb]4 ,!y appe> bright because ! *amb] is illum9at$ & ! cond5sation trails reflect light j z an ord9>y cl\d does4 ,illu/ration3 ,univ]sity ( ,cali=nia ,radiation ,laboratory #ab4 ,ano!r picture 9 ! ,wilson ,cl\d ,*amb]4 ,a l>ge numb] ( closely-spac$ tracks =m a cl\d4 7,! tracks are curv$ because ( ! pres5ce ( a magnetic field47 ,illu/ration3 ,,usaec--,argonne ,national ,laboratory #ac4 ,cutaway section ( a nucle> reactor4 ,! he>t ( ! reactor is a small region at ! c5t] :]e ! fission en]gy is g5]at$4 ,mo/ ( ! weight & volume are ne$$ = cool+ app>atus & %ield+ mat]ial to keep 9 nucle> radiation4 ,= ! radioactivity to affect areas at a l>ge di/ance f ! po9t ( ! explosion1 consid]able "t mu/ elapse :ile ! atomic cl\d rises & drifts 9 ! horizontal w9ds4 ,dur+ ?is "t m dis9tegrations occur1 due ma9ly to ! %ort-liv$ nuclei4 ,! rate at :i* !y occur keeps dim9i%+ z ! %ort-liv$ nuclei disappe>4 ,r\ghly speak+1 ! rate dim9i%es simply 9 proportion to ! "t4 ,m precisely1 ! rate drops some:at fa/]1 decreas+ by a factor ( t5 :5 ! "t increases by a factor ( sev54 ,a m9ute aft] ! explosion ! activity is less ?an "o p] c5t ( :at x is at a second4 ,aft] an h\r x is less ?an "o p] c5t ( its value at a m9ute4 ,?is law = ! decrease 9 activity ( fission products is1 ( c\rse1 q diff]5t f ! simple law ( radioactive decay4 ,! latt] law applies to a s+le radioactive species4 ,! fission products consi/ at any in/ant ( _m diff]5t radioactive species4 ,ea* "o obeys ! simple law ( radioactive decay1 b ! totality foll[s a diff]5t law4 ,x %\ld be kept 9 m9d t ! product nucleus ( a radioactive dis9tegration may itself be radioactive ) a diff]5t half-life4 ,= example1 !re is /rontium4 ,only a small am\nt ( ?is isotope is made directly 9 ! fission process4 ,! fission process yields l>ge quantities ( krypton1 :i* decays ) a half-life ( "o-half m9ute into rubidium4 ,! latt] has a half-life ( ?ree m9utes & decays into /rontium4 ,?is is h[ practically all ( ! /rontium is made 9 ! explosion4 ,?us bo? ! int5sity & ! nature ( ! radioactivity keep *ang+ ) "t4 ,^! facts are important because !y det]m9e ! magnitude & ! "* ( ! dang] :5 ! radioactivity f9ally falls out ( ! cl\d & is deposit$ on ! surface ( ! e>?4 ,^? radioactive p>ticles :i* dis9tegrate :ile /ill 9 ! cl\d ne$ n worry u s9ce ?is radiation c h no effect on liv+ organisms t may be und]nea?4 ,provid$ t ! cl\d is m ?an a few hundr$ feet above ! gr\nd1 ! beta & gamma rays releas$ 9 ^! dis9tegrations m]ely dissipate _! en]gy 9 ioniz+ ! air4 ,! "t :i* ! radioactive debris sp5ds 9 ! cl\d dep5ds mo/ critically on "o factor3 ! proximity ( ! explosion to ! gr\nd surface4 ,! nature ( ! surface1 :e!r x is soil or wat]1 also plays a role4 ,if ! explosion has tak5 place "r on ! gr\nd1 on a soil surface1 a lot ( big1 heavy dirt p>ticles become incorporat$ into ! fireball & beg9 to fall "u ! action ( gravity ev5 be=e ! cl\d /ops ris+4 ,?is fall\t cont9ues = a p]iod ( sev]al h\rs to p]haps a half day4 ,at ! same "t "s ( ! radioactive fission products :i* h adh]$ to ^! dirt p>ticles also fall out4 ,?is is ! orig9 ( ! s-call$ close-9 or local fall\t1 :i* ext5ds = a di/ance d[nw9d ( ! explosion ( a few miles to a few hundr$ miles1 accord+ to ! en]gy ( ! bomb & ! /r5g? ( ! w9ds4 ,approximately eighty p] c5t or s ( all ! fission products are acc\nt$ = by ?is close-9 fall\t 9 ! case ( a surface explosion4 ,! %ot on ,m>* #a1 #aied 0 ( ?is v>iety4 ,!re are sev]al possibilities = influ5c+ ! am\nt ( close-9 fall\t4 ,"o is to explode ! bomb ov] deep wat]4 ,9 ?is case ! close-9 fall\t am\nts to betwe5 ?irty & fifty p] c5t4 ,?is is because _m ( ! wat] drops to :i* radioactive p>ticles h adh]$ evaporate be=e !y hit ! gr\nd4 ,ov] %all[ wat]1 h[ev]1 if ! fireball actually t\*es ! bottom1 ! close-9 fall\t resembles ! case ( a l& explosion & is aga9 ab\t eighty p] c5t or s4 ,! close-9 fall\t = und]gr\nd or und]wat] explosions w be ev5 high] ?an = ! surface explosions4 ,9 fact a really deep und]gr\nd or und]wat] explosion w\ld be completely conta9$ & no activity w\ld be spread ar\nd4 ,ano!r possibility = r$uc+ ! close-9 fall\t is to detonate ! bomb on a t[] s tall t ! fireball _c t\* ! surface4 ,9 ?is case ! am\nt ( close-9 fall\t is r$uc$ f eighty p] c5t to approximately five p] c5t4 ,( c\rse1 x is n feasible to build t[]s = really big bombs ^: fireballs may be a mile or s 9 diamet]4 ,9 ?is case ! bomb might be dropp$ f an airplane to produce ! same effect4 ,! ,hiro%ima explosion 0 an example ( an air bur/ ( a small bomb4 ,! close-9 fall\t 9 t case 0 v small4 ,su* radiation sickness z occurr$ !re 0 due to ! direct gamma rays & neutrons releas$ 9 ! explosion itself4 ,9 ! case ( a ne>-surface explosion1 :]e ! fireball almo/ t\*es ! gr\nd1 ! close-9 fall\t is also only ab\t five p] c5t4 ,?is is a some:at surpris+ fact s9ce 9 ?is case photographs %[ l>ge quantities ( surface mat]ial be+ suck$ up into ! cl\d1 j z !y are 9 a true surface explosion4 ,?is mat]ial c]ta9ly consi/s ( l>ge1 heavy dirt p>ticles :i* subsequ5tly fall out ( ! cl\d4 ,yet mo/ ( !m someh[ fail to come 9 contact ) ! radioactive fission products4 ,?is peculi> ph5om5on c be und]/ood by look+ at ! details ( h[ ! fireball rises4 ,at fir/ ! c5tral "p ( ! fireball is mu* hott] ?an ! out] "p & ?us rises m rapidly4 ,z x rises1 h[ev]1 x cools & falls back ar\nd ! out] "p1 creat+ 9 ?is way a d\ghnut-%ap$ /ructure4 ,! :ole process is analog\s to ! =mation ( an ord9>y smoke r+4 ,9 mo/ ( ! photographs "o sees1 ! d\ghnut is obscur$ by ! cl\d ( wat] t =ms1 b sometimes :5 ! wea!r is p>ticul>ly dry1 x becomes p]fectly visible4 ,dur+ ! r ord]ly circulation ( air ?r\gh ! hole1 ! bomb debris & ! dirt t has be5 suck$ up rema9 sep>at$4 7,see pictures #a-d47 ,! close-9 fall\t acc\nts = only a portion ( ! radioactivity1 rang+ f less ?an a p] c5t = a high altitude %ot to almo/ complete deposition = "s gr\nd %ots4 ,= ! _w-wide fall\t we are int]e/$ 9 :at happ5s to ! rema9d]4 ,?is dep5ds on h[ ! atomic cl\d is c>ri$ by ! upp] w9ds = long di/ances4 ,9 ?is connection x is important to di/+ui% betwe5 a big bomb & a little bomb4 ,x is also important to di/+ui% betwe5 ! l[] & high] portions ( ! atmosph]e call$1 respectively1 ! troposph]e & ! /ratosph]e4 ,! atmosph]e is heat$ by ! sun 9 an indirect way4 ,! sun's rays pass ?r\gh air )\t w>m+ x4 ,!y heat up in/ead ! bottom ( ! atmosph]e1 t is1 ! solid gr\nd4 ,! atmosph]e is heat$ 9 ! same mann] 9 :i* a boil+ pot is heat$ on ! kit*5 range4 ,! heat is deliv]$ f bel[ & is c>ri$ 9 ris+ curr5ts to ! top4 ,only 9 ! case ( ! atmosph]e !re is no %>p upp] limit4 ,! curr5ts rise to an altitude ( ?irty to fifty ?\s& feet1 !n turn & desc5d4 ,?is boil+ "p ( ! atmosph]e is call$ ! troposph]e or region ( heat4 ,above x !re is less v]tical motion4 ,! upp] region is call$ ! /ratosph]e or /ratifi$ region4 ,= a little bomb ! atomic cl\d /ops ris+ be=e x rea*es ! /ratosph]e4 ,= a big bomb1 above ab\t a megaton ( en]gy 7a million tons ( ,,tnt equival5t71 ! cl\d pokes "r into ! /ratosph]e & keeps go+ to a height ( a hundr$ ?\s& feet or s4 ,! mo/ important fact ab\t ! /ratosph]e is ?is3 ,x has v little wea!r4 ,mo/ ( ! wea!r ph5om5a su* z cl\ds1 ra91 sn[1 fog1 mi/1 etc41 are conf9$ to ! l[] portion ( ! atmosph]e1 ! troposph]e4 ,! /ratosph]e1 h[ev]1 conta9s practically no wat]4 ,n[ suppose a little bomb ^: cl\d w rema9 9 ! troposph]e has be5 explod$ at "o ( ! ,unit$ ,/ates te/ sites4 ,! ,nevada te/ site is at a latitude ( #cg,n & ! ,pacific te/ site at #ab,n4 ,9 ^! middle latitudes1 9 ! troposph]e1 ! w9ds bl[ ma9ly f we/ to ea/ ) an av]age spe$ ( approximately #bj miles an h\r4 ,!re w be a slight s\!rly or nor!rly motion on top ( ?is4 ,b by & l>ge ! radioactive cl\d w /ay 9 a pretty n>r[ b& ar\nd ! latitude at :i* ! explosion took place4 ,aft] ! fir/ few h\rs1 :5 ! close-9 fall\t has dw9dl$1 ! radioactive p>ticles rema9+ 9 ! cl\d are too light & too f9e to fall any m "u ! action ( gravity4 ,at ?is po9t ! wea!r becomes important4 ,ra91 fog1 or mi/ captures ! radioactive p>ticles1 & returns !m to ! gr\nd 9 ! ra9fall4 ,?is results 9 ! s-call$ troposph]ic fall\t4#ab ,! av]age "t = ?is fall\t to occur is approximately two weeks to a mon?4 ,dur+ ?is "t1 :ile /ay+ m or less 9 ! latitude ( ! explosion1 ! radioactive p>ticles may actually h encircl$ ! e>?4 ,! cl\ds ( ! big bombs rise high into ! /ratosph]e4 ,! w9ds 9 ! /ratosph]e d n bl[ s pr$om9antly 9 a latitud9al direction4 ,:at is m important1 !y /ay 9 ! /ratosph]e = ye>s1 9 :i* "t ! radioactivity is di/ribut$ to all areas ( ! globe4 ,! fall\t f ! big bombs is ?us really _w-wide4 ,! troposph]ic fall\t takes ab\t a mon?4 ,! /ratosph]ic fall\t takes #e to #aj ye>s4 ,! reason = ?is diff]5ce is ! wea!r1 or r ! lack ( x4 ,9 ! /ratosph]e !re is no ra9 or fog to cat* ! radioactive p>ticles & h5ce no effective me*anism = produc+ ! fall\t4 ,9 fact1 s9ce ! radioactive p>ticles are too f9e to fall by gravity1 !y mu/ simply wait until "s turbul5t motions impel !m d[nw>d back into ! troposph]e4 ,?is process requires a long "t4 ,t ra9fall is ! mo/ important me*anism = produc+ ! _w-wide fall\t has be5 %[n by exam9+ ! fall\t 9 c]ta9 dry regions ( s\!rn ,cali=nia & ,s\? ,am]ica4 ,9 e case ! fall\t 0 f\nd to be consid]ably sub-normal4 ,9 "o place 9 ,*ile1 :]e !re is nev] any ra91 ! fall\t 0 f\nd to be only "o p] c5t ( :at might be expect$ on ! basis ( ! av]age fall\t at ! same latitude4 ,9 regions hav+ at lea/ a few in*es ( ra9 p] ye>1 ! fall\t t5ds to be proportional to ! ra9fall on ! av]age4 ,h[ev]1 ! proportionality to ra9fall dep5ds on ! nature ( ! wea!r s t1 say1 tw5ty in*es ( ra9 9 "o "p ( ! _w may n give z mu* fall\t z ! same am\nt ( ra9 9 o!r wea!r zones4 ,we are rapidly le>n+ ab\t ?is4 ,hav+ said :at ! age is ( ! v>i\s k9ds ( fall\t1 we are 9 a position to say :i* radioactive species are /ill pres5t :5 ! radioactivity is deposit$ on ! gr\nd4 ,! close-9 fall\t1 be+ only a few h\rs old1 /ill includes _m %ort-liv$ isotopes1 :i* dis9tegrate be=e !re is a possibility ( +e/ion or inhalation into ! body4 ,consequ5tly ! dang] f ! close-9 fall\t results f ext]nal exposure1 ma9ly to gamma radiation on ! :ole body1 & to a less] ext5t to en]getic beta rays on ! sk94 ,clo!s & ord9>y h\s+ provide relatively little %ield+ aga9/ gamma rays4 ,special protective %elt]s are ne$$4 ,dur+ a w> if ! enemy 7 to bomb our cities ) sup]-megaton weapons surface-bur/1 ! close-9 fall\t w\ld be a f> great] ag5t ( de/ruction aga9/ an un%elt]$ populace ?an ei!r bla/ or !rmal radiation4 ,9 ! /ratosph]ic _w-wide fall\t1 h[ev]1 all ( ! %ort-liv$ radioactivity has disappe>$1 s9ce a p]iod ( _m ye>s has elaps$ s9ce ! explosion4 ,aft] a ye> or s ! only gamma emitt] :i* is left 9 appreciable quantity is cesium1 ) a half-life ( #cj ye>s4 ,its gamma ray1 h[ev]1 is n v p5etrat+4 ,9 spite ( ?is fact cesium is consid]$ to be ! second mo/ important haz>d = ! long t]m fall\t4 ,! fir/ is /rontium1 :i* is a beta emitt] ) a half-life ( #bh ye>s4 ,?is is long en\gh s t mo/ ( ^! nuclei w /ill be pres5t ev5 aft] sp5d+ a long "t 9 ! /ratosph]e4 ,s9ce /rontium is *emically simil> to calcium1 x contam9ates our food/uffs & is easily incorporat$ into our bodies4 ,once inside x /ays = long p]iods ( "t1 deposit$ 9 our bones4 ,we %all see 9 a lat] *apt] h[ s]i\s ?is dang] may be4 ,! troposph]ic fall\t1 & to a less] ext5t1 ! /ratosph]ic1 includes "s o!r radioactive species besides cesium & /rontium1 & we %all discuss ^! 9 ! next *apt]4 ,b by & l>ge !y are ( little consequ5ce 7) ! possible exception ( iod9e7 ei!r because !y are n easily absorb$ 9 ! body or else because _! radiation is n v en]getic4 ,! _w-wide haz>d is ?us n>r[$ d[n to j two isotopes1 an int]nal beta emitt] & a weak gamma emitt]4 ,,*apt] ,,xi ,f ! ,soil to ,man ,!re is a bewild]+ v>iety ( radioactive products deposit$ 9 ! fall\t4 ,giv5 c]ta9 conditions all ( !m c\ld be dang]\s to man4 ,actually1 v few are4 ,an example ( a radioactive isotope :i* is produc$ 9 l>ge quantity by ! fission process & ab\t :i* !re is "s reason to worry1 b actually is n dang]\s to man1 is iod9e4 ,?is isotope 9 ! fall\t is n dang]\s because x has a r %ort half-life3 eight days4 ,dur+ ! fir/ weeks aft] a nucle> explosion "s radioactive iod9e may fall out ( ! cl\d & contam9ate graz+ l&4 ,a c[ eats hundr$s ( p\nds ( grass 9 a few days "t4 ,n[ iod9e is f\nd 9 ! c['s body or 9 ! body ( any mammal ma9ly 9 "o spot4 ,?is is ! ?yroid gl& locat$ 9 man ne> ! ,adam's apple4 ,! ?yroid gl& is important because x secretes a *emical :i* regulates _m ( ! body functions4 ,9 man1 ^! include h[ we burn up our food & 9 :at mood we are4 ,ab\t tw5ty p] c5t ( all ! iod9e :i* is tak5 up1 :e!r radioactive or natural1 is conc5trat$ 9 ?is "o r small gl&4 ,su* a conc5tration is precisely ! k9d ( dang] = :i* we mu/ wat*4 ,%ortly aft] nucle> te/s1 c[s t graze on range l& h be5 f\nd ) abnormally l>ge am\nts ( radioactive iod9e1 al?\gh n s l>ge z to be h>mful4 ,9 human be+s1 h[ev]1 ! measur$ levels ( radioactive iod9e are less ?an a hundr$? ( :at !y are 9 ! c[s because by ! "t ?is radioactive isotope has rea*$ man1 x has mo/ly decay$ into a /able1 h>mless v>iety ( x5on gas4 ,!re are _m pot5tially dang]\s isotopes 9 ! radioactive debris ( a nucle> explosion4 ,b mo/ ( !m decay too soon to affect man4 ,isotopes :i* live an extremely long "t comp>$ to ! human life-span are also n dang]\s to man4 ,a radioactive p>ticle 9 ! body is n h>mful unless x dis9tegrates & releases its en]gy :ile ! individual is /ill alive4 ,two examples ( long-liv$ radioactive isotopes1 :i* are us$ z fuel 9 ! bombs & :i* may be left ov] f ! explosion 9 l>ge quantities1 are3 uranium & plutonium4 ,uranium has a half-life ( #gaj million ye>s1 :i* is mu* too long to be dang]\s4 ,plutonium has a half-life ( #bd1jjj ye>s & is some:at m dang]\s4 ,! dang] f plutonium arises because x emits an en]getic alpha ray4 ,! dang] f radioactivity dep5ds on ! k9d ( p>ticle emitt$--alpha1 beta1 or gamma rays--& :e!r ^! rays attack ! body f ! inside or ! outside4 ,f ! outside ! gamma rays are ! mo/ dang]\s & ! alpha rays ! lea/ dang]\s4 ,f ! inside ! ord] is j rev]s$4 ,to cause damage f ! outside ! radiation mu/ be v p5etrat+4 ,gamma rays c g ?r\gh ! :ole body4 ,beta rays are /opp$ 9 ! sk9 tissue4 ,alpha rays _c ev5 p5etrate ! out] lay] ( non-liv+1 protective sk94 ,on ! inside1 h[ev]1 9 ! s5sitive organs1 ! %ort range ( ! alpha rays makes !m exce$+ly dang]\s4 ,_! en]gy is conc5trat$ 9 a small am\nt ( tissue to :i* damage is sev]e4 ,! beta rays cause a slightly less conc5trat$ damage1 & ! gamma rays ! lea/ conc5trat$ ( all4 ,radioactivity may ent] ! body z contam9ation 9 ! food we eat or 9 ! air we brea!4 ,to be dang]\s1 h[ev]1 x mu/ rema9 9 ! body1 ei!r 9 ! inte/9es or ! lungs or 9 o!r vital organs1 long en\gh = dis9tegrations to occur1 :i* w ionize & injure ! liv+ cells4 ,=tunately1 plutonium 9 our food is easily excret$ f ! body4 ,only a few ?\s&?s ( a p] c5t ( :at is eat51 is actually absorb$4 ,if inhal$1 l>ge p>ticles are /opp$ 9 ! nasal passages4 ,small p>ticles get into ! lungs b are quickly exhal$4 ,only int]m$iate siz$ p>ticles are absorb$4 ,h[ev]1 ! plutonium :i* is absorb$ g5]ally gets laid d[n 9 ! bones1 :]e x /ays = a long p]iod ( "t4 ,altoge!r1 plutonium 9 ! small am\nts we usually deal ) is n "o ( ! great] dang]s to human be+s4 ,p]haps its mo/ disagreeable prop]ty is t1 be+ an alpha emitt]1 x is n v easy to detect4 ,s9ce alpha p>ticles d n p5etrate ?r\gh ! surface ( mo/ radiation met]s1 special in/rum5ts are ne$$ to f9d !m4 ,two fission products :i* are readily absorb$ ^u +e/ion are3 /rontium 7,sr7 & cesium 7,cs74 ,dep5d+ some:at on _! *emical =m1 approximately ?irty-five p] c5t ( ! ,sr is absorb$1 & all ( ! ,cs is absorb$4 ,bo? ( ^! isotopes are pl5tifully made 9 ! fission process4 ,moreov] !y h v 8dang]\s0 half-lives--ab\t #cj ye>s--:i* is long en\gh s t decay is negligible betwe5 ! explosion & contact ) man1 b %ort en\gh s t decay is probable aft] contact4 ,f su* argum5ts z ^! "o concludes t ,sr & ,cs are ! mo/ important isotopes = ! int]nal haz>d f ! _w-wide fall\t4 ,"o c be reasonably sure t !re are no o!rs ( importance1 because c>eful & ext5sive rese>* has n f\nd significant am\nts ( any 9 our bodies4 ,we ne$ n fe> t "o has be5 ov]look$1 because ! beta activity ( ! fission products is always easy to detect4 ,! two ma9 que/ions :i* we h to answ] are ^!3 ,9 :at precise way w ! dang]\s elem5ts ,sr & ,cs be di/ribut$ 9 ! body8 ,& aft] !y are di/ribut$1 :at k9d ( damage w !y produce8 ,we "k too little ab\t ! *emi/ry ( ! liv+ body to obta9 a complete answ] to ! second "q4 ,h5ce x has to be admitt$ t ! actual dang] _c be /at$ 9 a precise way4 ,=tunately1 en\gh is kn[n f direct exp]i5ce to obta9 a good value = ! greate/ damage t might be produc$4 ,9 ! pres5t *apt] we %all describe :at is kn[n ab\t ! uptake ( ! dang]\s elem5ts into ! body4 ,9 foll[+ *apt]s we %all turn to ! "q ( ! biological consequ5ces4 ,we may beg9 by comp>+ ! dang] f ,cs ) t f ,sr4 ,bo? ( ^! isotopes are made 9 ! fission process 9 ab\t equal numb]s4 7,r\ghly #b or #b p] c5t ( all ! fission products are ,sr1 & #c p] c5t ,cs47 ,!y h approximately ! same radioactive half-lives4 ,b !y diff] 9 an important respect3 ,! ,cs is deposit$ m or less uni=mly ?r\gh\t ! body2 ! ,sr is conc5trat$ 9 ! bones4 ,cs emits a l>ge "p ( its radioactive en]gy 9 ! =m ( a gamma ray1 :i* causes ionization uni=mly 9 ! body4 ,sr1 on ! o!r h&1 emits all ( its en]gy 9 ! =m ( two beta rays1 :i* h ranges ( only a small fraction ( an in* 9 ! bone4 ,?us 9 ! "o case ! radioactive dis9tegration en]gy is di/ribut$ 9 ! :ole body2 9 ! o!r1 ! en]gy is deposit$ 9 ! bones only4 ,s9ce ! bones comprise ab\t t5 p] c5t ( ! total body weight1 !y are subject$ to t5 times ! radiation dosage4 ,! bones are q s5sitive to radiation1 & an ov]dosage c cause bone canc] & int]f]e ) ! production ( blood cells t goes on 9 ! m>r[4 ,?us we are l$ to ! conclusion t ,sr is a f> great] pot5tial haz>d ?an ,cs4 ,a fur!r po9t1 :i* leads to ! same conclusion1 is t ,cs1 aft] be+ absorb$1 is reta9$ 9 ! body less ?an six mon?s & !n excret$4 ,sr is reta9$ = _m ye>s4 ,on ! o!r h&1 ,cs c cause a type ( damage :i* ,sr _c cause3 namely1 damage to ! reproductive cells4 ,! effect ( ,sr is inde$ limit$ to ! bones & adjac5t or ne>by bone m>r[1 & does n rea* ! reproductive organs4 ,9 a lat] *apt] we %all take up ! "q ( g5etic dang]1 & !n we %all be v int]e/$ 9 ,cs4 ,= ! rema9d] ( ?is *apt]1 h[ev]1 we may focus our att5tion on ,sr4 ,s9ce a l>ge fraction ( ! ,sr :i* ent]s ! body /ays !re1 ! mo/ important que/ions :i* rema9 are3 h[ x gets !re & h[ mu* gets !re4 ,! ess5tial fact 9 ?is connection is t ! ,sr g5]ally occurs 9 ! fall\t 9 a *emical =m :i* is easily dissolv$ 9 wat]4 ,! wat] is tak5 up by plants1 by absorption ?r\gh ! leaves & ! roots4 ,animals graze on ! plants4 ,human be+s eat ! plants & dr9k ! milk f ! graz+ animals1 & ?us become expos$ to ,sr4 7,see pictures #e & #f47 ,"o might worry because ,sr is n a naturally occurr+ isotope b has be5 made = ! fir/ "t by man 9 ! fission process4 ,"h is an unfamili> poison be+ scatt]$ ov] ! e>?4 ,c we h any idea h[ mu* w be tak5 up by human be+s8 ,! answ] dep5ds on a fact :i* we h emphasiz$ ?r\gh\t ?is book3 t isotopes ( ! same elem5t are *emically & biologically indi/+ui%able4 ,! radioactive v>iety ( /rontium w behave exactly l ! /able natural v>iety4 ,9 p>ticul>1 ! ratio ( ,sr to /able /rontium 9 ! human body mu/ be ! same z ?is ratio is 9 our food4 ,f ?is premise we c pr$ict h[ mu* ,sr w rea* ! human body4 ,f ! total yield ( fission en]gy releas$ 9 all nucle> te/s to date1 "o c calculate exactly h[ mu* ,sr has be5 produc$4 ,?is am\nt turns out to be ab\t #ajj p\nds4 ,approximately "o half ( ?is am\nt has be5 deposit$ 9 & ne> ! te/ sites 9 ! close-9 fall\t4 7,mo/ ( ! radioactivity comes f ! big bombs1 & mo/ ( ^! h be5 bur/ on ! gr\nd or ov] %all[ wat]47 ,a small portion ( ! #ajj p\nds has dis9tegrat$ 9 ! cl\d4 ,! rema9d]1 r\ghly #ej p\nds1 is p>tially /ill 9 ! /ratosph]e & p>tially has be5 dissem9at$ ar\nd ! _w 9 ! troposph]ic & /ratosph]ic fall\t4 ,at ! pres5t "t measurem5ts %[ t #be or #cj p\nds h actually be5 return$ to ! surface ( ! e>?4 ,local values v>y f ab\t "o ?ird to m ?an twice ! av]age _w-wide value4 ,9 ! nor!rn "p ( ! ,unit$ ,/ates1 9 ! regions ( frequ5t ra9fall1 ! measur$ values are ab\t twice ! _w-wide av]age4 ,9 ! latitudes betwe5 #aj,s & #ej,n ! av]age value is ab\t #ej p] c5t great] ?an ! _w-wide av]age4 ,= ! re/ ( ! _w "o f9ds1 ) "s v>iations1 ab\t "o ?ird ! _w-wide av]age4 ,mo/ ( ! ,sr fall\t is caught 9 ! top two or ?ree in*es ( ! soil4 ,x exi/s !re 9 a wat]-soluble =m t is readily assimilat$ by plants4 ,also 9 ! soil1 *emically insep>able f ! ,sr1 is /able natural /rontium4 ,plants1 animals1 & human be+s h no way ( di/+ui%+ betwe5 ! two4 ,x is n easy to det]m9e h[ mu* natural /rontium is 9 a =m :i* is available to ! plants4 ,"s ( ! natural /rontium is insoluble2 & "s is bel[ ! root dep?4 ,our be/ e/imate is t !re are ab\t #fj p\nds p] acre actually available = uptake by ! plants4 ,?is is1 ( c\rse1 an av]age4 ,! am\nt ( natural /rontium 9 ! human body is a quantity we "k r well4 ,x has be5 c>efully measur$ & is ab\t #j4g gram 9 ! av]age adult1 ) proportionately less 9 *ildr54 ,n[ s9ce we "k h[ greatly ,sr has be5 dilut$ 9 ! soil & h[ mu* natural /rontium !re is 9 our bodies1 we c calculate ! expect$ quantity ( ,sr 9 our bones4 ,consid]+ ! _m unc]ta9ties 9 ! calculation "o %\ld n expect too good an agreem5t4 ,! rem>kable fact is t ! quantity ( ,sr measur$ 9 small *ildr5 does agree ) ! calculat$ am\nt4 ,= adults ! measur$ value is q a bit less ?an ! calculat$ am\nt because adult bones h be5 made = ! mo/ "p be=e !re 0 any ,sr 9 ! environm5t4 ,! fact t we c calculate h[ mu* ,sr is at pres5t 9 ! body is mo/ important because x gives u confid5ce t we und]/& :at is happ5+4 ,x is especially important = u to und]/& :at is happ5+ s t we c pr$ict h[ nucle> te/s :i* are c>ri$ out today w affect future levels ( ,sr 9 ! body4 ,f argum5ts su* z we h giv51 plus a record ( ! ,sr cont5t ( bones ov] ! la/ sev]al ye>s1 x seems unlikely t ! level ( ,sr w increase by m ?an a factor ( two or s due to te/s already conduct$4 ,actually ?is factor may be ev5 small] bo? because ( ! mix+ ( ! /rontium ) ! deep] lay]s ( ! soil1 & because ! radioactive /rontium :i* /ays 9 ! gr\nd = a long "t t5ds to become *emically less soluble & mix$ m ?or\ghly ) t "p ( ! natural /rontium :i* is *emically unavailable4 ,?is latt] process is call$ 8*emical ag+40 ,to foll[ radioactive /rontium & normal /rontium f ! soil into ! food & ! bones is n an easy matt]4 ,we mu/ worry ab\t ! "q ( ! /rontium dep? 9 ! soil & ! *emical =m ( ! /rontium4 ,! complete id5tity ( ,sr & normal /rontium holds only if bo? are ne> ! same place & 9 ! same *emical =m4 ,a fur!r difficulty is t until rec5tly little 0 kn[n ab\t ! behavior ( normal /rontium & k is accumulat+ sl[ly4 ,mu* m is kn[n ab\t calcium4 ,n[ calcium & /rontium d n behave 9 an id5tical way1 b !y d behave simil>ly4 ,9 pass+ f soil to man ! ratio ( calcium to /rontium does n rema9 ! same b at lea/ x *anges 9 a m or less def9ite mann]4 ,actually mo/ "w on ,sr uptake has be5 done by comp>+ ,sr ) calcium4 ,9 ord] to use ! data on calcium "o has to f9d out h[ ! calcium to /rontium ratio is *ang$ :5 ! mat]ial is tak5 up into ! human body4 ,9 ! soil !re is1 on ! av]age1 ab\t #a "p ( /rontium to #ajj p>ts ( calcium4 ,9 ! human body ! ratio is ab\t #a to #adjj4 ,?us ! /rontium is discrim9at$ aga9/ relative to calcium 9 go+ f ! soil to man by a factor ( ab\t #ad4 ,?is is a factor ( protection4 ,x is good to d\ble-*eck ?is conclusion & to f9d out h[ ! calcium to /rontium ratio *anges /ep by /ep 9 go+ f ! soil to man4 ,"o f9ds a factor ( #a4d 9 go+ f ! soil to ! plant1 a factor ( #g 9 go+ f ! plant to ! milk1 & a factor ( ab\t #b 9 go+ f ! milk to man4 ,actually1 if we put all ^! factors toge!r we %\ld expect t on ! way f ! soil to man ! calcium to /rontium ratio increases by a factor #bj4 ,?is is 9 reasonable b n 9 excell5t agreem5t ) ! ratio #ad giv5 above4 ,once ! factor ( protection is e/abli%$ we c get a value ( ! expect$ /rontium uptake f ! way 9 :i* ! radioactive mat]ial is dilut$ by calcium r ?an by normal /rontium4 ,?is is a less /raight=w>d b1 = ! "t be+1 a m practical me?od ?an ! direct ,sr--normal /rontium comp>ison4 ,x is p>ticul>ly important :5 "o comp>es soils ( r diff]5t calcium cont5t4 ,plants & animals require calcium4 ,:5 !y d n get x1 !y develop a calcium-hung]4 ,s9ce /rontium is *emically simil> to calcium1 a lack ( calcium 9 ! soil is readily sub/itut$ by available /rontium4 ,"o w\ld expect t plants gr[n on calcium-poor soil & animals rais$ on su* l& w\ld exhibit abnormally high natural /rontium cont5t & also a proportionately high ,sr cont5t4 ,! high ,sr cont5t has 9 fact be5 v]ifi$4 ,"s %eep 9 ,wales1 = example1 appe> to h ab\t t5 times ! av]age am\nt ( ,sr 9 _! bodies4 ,=tunately mo/ p d]ive _! food f _m areas widely sep>at$ f ea* o!r4 ,soil t is defici5t 9 calcium is n likely to supply m ?an a small "p ( an individual's su/5ance4 ,h[ev]1 ! possibility ( a l>ge fluctuation _c be ignor$4 ,9 ?is ev5t corrective measures w\ld be ne$$4 ,"o simple measure w\ld be to f]tilize defici5t soil ) additional calcium4 ,t soil c be successfully treat$ 9 ?is way is illu/rat$ by ! pres5t situation 9 ,wales4 ,! %eep ) ! abnormally high ,sr cont5t all come f ! /eep1 poor pa/ures :i* are n lim$4 ,! %eep f ! l[] pa/ures1 :i* are lim$ 7n because ( ! fall\t b = economic reasons71 %[ an activity ( only "o ?ird ! value m5tion$ above4 ,! po9t we h tri$ to make 9 ?is *apt] is t ! pres5t human levels ( ,sr c be satisfactorily acc\nt$ = by simple argum5ts bas$ on ! *emical simil>ity ( elem5ts & ! id5tity ( isotopes4 ,^! argum5ts give u confid5ce t we correctly und]/& h[ ,sr & h[ mu* ,sr is gett+ f ! soil to ! human body4 ,at ! same "t we h se5 h[ _m factors influ5ce ! ev5tual uptake into ! human body3 geographical latitude1 frequ5cy ( ra9fall1 ! *emical =m 9 :i* /rontium is f\nd1 ! calcium cont5t ( ! soil1 ! me?od ( agriculture4 ,ev5 ?\gh ! ,unit$ ,/ates has pu%$ ?is inve/igation vigor\sly s9ce #aieb ! bulk ( ! "w is /ill ahead ( u4 ,= in/ance1 9 ! ,unit$ ,/ates1 dairy products provide mo/ ( ! calcium & /rontium 9 our diets4 ,9 ,japan1 h[ev]1 ! situation is some:at diff]5t4 ,!re ! ma9 s\rce ( calcium & /rontium is rice4 ,z a result1 ! ratio ( /rontium to calcium may be pass+ diff]5tly f ! soil to man4 ,also ! fall\t /rontium might be wa%$ deep] into ! soil & ! soluble to non-soluble ratio might be diff]5t4 ,consid]+ ! complex nature ( ! ,sr uptake into man1 x is important to keep close track ( ! actual ,sr levels 9 ! soil1 9 our food1 & 9 our own bodies4 ,! foll[+ graphs %[ h[ ^! levels h ris5 9 ! la/ sev]al ye>s due to ! bomb te/s3 ,illu/ration3 ,sr 9 ! soil--measur$ 9 ?\s&?s ( a gram p] squ>e mile4 ,illu/ration3 ,av]age ,sr 9 ,u4,s4 milk--measur$ 9 trillion?s ( a gram p] qu>t4 ,illu/ration3 ,av]age radiation doses f ,sr 9 bones ( "y *ildr5 7,u4,s47--measur$ 9 ro5tg5s p] ye>4 ,! actual am\nts ( ,sr 9 ! soil1 9 ! milk1 & 9 ! bones ( "y *ildr5 are only approximately kn[n4 ,b ! ma9 po9t t we are try+ to illu/rate1 is t s9ce #aied ! buildup ( ,sr has gone on at a r /eady rate4 ,h[ f> w ?is buildup cont9ue8 ,m radioactivity 0 releas$ 9 te/s 9 ! ye> #aied ?an 9 all o!r ye>s put toge!r4 ,probably m ?an "o-half ( t activity has already be5 deposit$4 ,s9ce t "t ! fission en]gy produc$ 9 ,u4,s4 te/s has /eadily decreas$4 ,fur!rmore1 we h le>n$ h[ to m9imize ! _w-wide fall\t by employ+ gr\nd bur/s :i* deposit mo/ ( _! activity 9 ! close-9 fall\t ne> ! te/ site4 ,x is also possible to place *emical additives ne> ! bomb 9 ord] to conv]t ! /rontium into a m insoluble =m or else into a =m :i* w m readily fall out 9 ! imm$iate neighborhood ( ! explosion4 ,& :at is mo/ important--we are develop+ clean nucle> weapons1 :i* produce bla/ & heat b greatly r$uc$ radioactivity4 ,9 ! future ^! clean weapons may elim9ate ! additional radioactivity altoge!r4 ,x is h>d to make pr$ictions ab\t ! plans ( all nations4 ,if we f9d--& o!rs also f9d--t clean weapons are ! mo/ desirable1 ! total /rontium contam9ation is n likely to become m ?an p]haps two to f\r times ! pres5t value4 ,we believe t all reasons--respect = human life1 milit>y consid]ations & simple sanity--lead to "o conclusion4 ,9 ! developm5t ( nucle> explosives we mu/ endeavor to make !m clean4 ,b ! real reason = ?is does n lie 9 ! small contam9ation due to te/s4 ,! real reason is t w> c\ld turn contam9ation into a dang] to c\ntless p4 ,,*apt] ,,xii ,dang] to ! ,individual ,h[ mu* h>m is be+ done by ! atomic te/s8 ,"s sci5ti/s h claim$ t f pa/ te/s alone ab\t #ej1jjj p]sons ?r\gh\t ! _w w die prematurely4 ,!re is no g5]al agreem5t on ?is po9t4 ,"s ?9k ! numb] %\ld be small]4 ,x is possible t radioactivity produces "s effects :i* prolong life r ?an %ort5 x4 ,b ev5 if all ! biological consequ5ces ( radiation 7 kn[n _m que/ions w\ld /ill dem& answ]s4 ,c te/s be ju/ifi$ if !y actually %ort5 "s human lives8 ,ev5 ! possibility ( a heal? haz>d mu/ be tak5 mo/ s]i\sly4 ,on ! o!r h&3 ,are !re any reasons :i* make cont9u$ te/+ necess>y8 ,we %all return to ^! que/ions 9 a lat] *apt]4 ,fir/1 h[ev]1 we %all try to put be=e ! read] ! kn[n facts ab\t ! fall\t dang] to ! individual4 ,we %all try to put ?is dang] into p]spective by relat+ x to o!r m famili> dang]s to :i* all ( u are expos$4 ,9 ! foll[+ *apt] we %all discuss h[ ! fall\t may affect future g5]ations4 ,! dang]s f big doses ( radiation are well kn[n4 ,exposure to a ?\s& ro5tg5s ov] our :ole body causes almo/ c]ta9 dea? 9 less ?an ?irty days4 ,f\r or five hundr$ ro5tg5s give a fifty-fifty *ance ( survival4 ,at less ?an a hundr$ ro5tg5s1 !re is no dang] ( imm$iate dea?4 ,?ree ye>s ago ! ,m>%allese got a dose ( #age ro5tg5s4 ,none di$4 ,app>5tly all are 9 good heal?4 ,ov] long] p]iods ( "t ev5 bigg] radiation doses c be tol]at$4 ,a ?\s& ro5tg5s spread ov] a lifetime produce no app>5t biological consequ5ces 9 individual cases4 ,a r\gh rule 7:i* is n too well-e/abli%$7 is t five times z mu* radiation c be tol]at$ if "o is expos$ to only a little radiation at any "o "t4 ,a hundr$ ro5tg5s all at once1 or sev]al times ?is am\nt ov] a protract$ "t p]iod1 w n cause sickness or dea? t c be directly blam$ on ! radiation4 ,h[ev]1 su* a dose ( radiation may h h>mful biological consequ5ces :i* are m subtle4 ,an expos$ individual may develop an increas$ susceptibility to c]ta9 diseases1 notably bone canc] & leukemia4 ,leukemia is a fatal disease 9 :i* ! :ite blood cells multiply too rapidly4 ,a p]son :o receives a hundr$ ro5tg5s does n necess>ily contract bone canc] or leukemia4 ,r1 8 *ance ( contract+ ^! diseases dur+ 8 lifetime may h be5 increas$4 ,k ( ?is k9d c be obta9$ only ) ! help ( /ati/ics4 ,if1 = example1 a l>ge numb] ( mice receive a heavy dosage ( radiation ov] a long p]iod ( "t1 "o f9ds t ! incid5ce ( tumors & leukemia is high] among/ su* irradiat$ animals ?an ! natural incid5ce ( ^! diseases4 ,direct evid5ce ) human be+s--=tunately--is r sc>ce4 ,/ati/ics exi/ on ! survivors ( ,hiro%ima & ,nagasaki1 & also on radiologi/s4 ,! latt] gr\p probably receive sev]al hundr$ ro5tg5s dur+ _! pr(essional lifetimes4 ,9 addition1 "s /ati/ics exi/ on *ildr5 :o h be5 treat$ ) l>ge doses ( radiation = enl>g$ ?ymuses4 ,p]sons suff]+ f ankylos+ spondylitis1 :i* is a pa9ful disease ( ! sp9al jo9ts1 h also be5 treat$ ) l>ge ,x-ray doses4 ,! /ati/ics 9 all ^! cases lead to ! same conclusion3 t l>ge doses ( radiation increase ! likelihood t an individual's life w be %ort5$ by leukemia & possibly also o!r canc]s4 ,fur!rmore1 x appe>s 7ma9ly f ! exp]im5ts on animals7 t ! increas$ likelihood is simply proportional to ! am\nt ( radiation receiv$1 at lea/ = doses 9 ! neighborhood ( sev]al hundr$ ro5tg5s or s4 ,?is ( c\rse s\nds fright5+4 ,b ! radiation doses f ! _w-wide fall\t are 9 a completely diff]5t class f ^? we h be5 discuss+4 ,!y are v mu* small]4 ,on ! av]age human bones are gett+ ab\t #j4jjb ro5tg5s p] ye> f ! ,sr 9 ! fall\t4 ,9 addition ! :ole body is receiv+ a r\ghly equal am\nt 9 gamma rays1 ma9ly f ,cs4 ,^! figures apply to new bone 9 "y *ildr5 :o h gr[n up 9 an environm5t ( ,sr 9 ! nor!rn "p ( ! ,unit$ ,/ates4 ,?is is a region ( maximum fall\t4 ,adults ^: bones 7 made = ! mo/ "p be=e ! atomic te/+ />t$ are gett+ ab\t #j4jjjc ro5tg5s p] ye> f ,sr4 ,none ( ^! figures appe>s to be al>m+4 ,at ?is pres5t rate a lifetime dosage 9 nor!rn ,u4,s4 is only a small fraction ( a ro5tg54 ,a r>e individual might get sev]al times ?is am\nt4 ,if te/s cont9ue at ! pres5t rate1 radiation levels c\ld increase by z mu* z five-fold4 ,h[ev]1 ev5 9 ?is situation x is difficult to imag9e anyone receiv+ a lifetime dose ( m ?an five or t5 ro5tg5s f ! _w-wide fall\t4 ,a m reasonable e/imate = ! av]age lifetime dose w\ld be a few ro5tg5s or less4 ,"o might conclude f ^! figures t !re is no dang] :atsoev] f ! fall\t4 ,?is conclusion1 h[ev]1 may n be correct4 ,! dang] f su* small doses ( radiation is n easy to def9e4 ,ev5 ! be/ /ati/ical me?ods are insuffici5t4 ,"o is look+ = small effects :i* %[ up only aft] millions ( cases h be5 /udi$4 ,animal exp]im5ts are extremely difficult to c>ry out "u ^! conditions4 ,direct controll$ exp]i5ce ) human be+s is1 ( c\rse1 impossible4 ,z a result1 "o is =c$ to draw conclusions f ! effects at high] dose levels1 :]e exp]im5tal data h be5 obta9$4 ,?is may be done 9 _m ways4 ,"o way is to assume t ! law ( proportionality holds d[n to ! smalle/ doses4 ,?is means t "o ro5tg5 produces "o hundr$? z _m cases ( bone canc] & leukemia z #ajj ro5tg5s produce4 ,?is law is plausible4 ,x is by no means prov54 ,by argu+ 9 ?is way "o f9ds t = ea* megaton ( fission en]gy :i* escapes f ! te/ site 9 ! _w-wide fall\t ! lives ( approximately f\r hundr$ p]sons w\ld be %ort5$ by leukemia or bone canc]4 ,"u pres5t conditions ( te/+1 r\ghly "o half ( ! fission products are deposit$ z close-9 fall\t 9 & ne> ! te/ site4 ,p] megaton ( fission en]gy explod$1 !re=e1 p]haps #bjj p]sons may get leukemia or bone canc]4 ,?is figure c\ld actually be high]1 possibly ev5 a ?\s& p]sons or m p] megaton4 ,x c\ld also be l[]4 ,x c\ld be z]o4 ,x is possible t radiation ( less ?an a c]ta9 int5sity does n cause bone canc] or leukemia at all4 ,9 ! pa/ small doses ( radiation h (t5 be5 reg>d$ z b5eficial4 ,?is 0 n support$ by any sci5tific evid5ce4 ,today _m well-in=m$ p believe t radiation is h>mful ev5 9 ! smalle/ am\nts4 ,?is /atem5t has be5 repeat$ 9 an au?oritative mann]4 ,actually !re c be little d\bt t radiation hurts ! individual cell4 ,b a liv+ be+ is a mo/ complex ?+4 ,damage to a small fraction ( ! cells might be b5eficial to ! :ole organism4 ,"s exp]im5ts on mice seem to %[ t exposure to a little radiation increases ! life expectancy ( ! animals4 ,sci5tific tru? is firm--:5 x is complete4 ,! evid5ce ( :at a little radiation w d to a complex animal l a human be+ is 9 an e>ly & unc]ta9 /ate4 ,9 any ev5t ! numb] ( additional cases ( leukemia & bone canc] due to ! fall\t radiation is c]ta9ly too small to be notic$ aga9/ ! natural incid5ce ( ^! disord]s4 ,9 ! next ?irty ye>s ab\t #f1jjj1jjj p ?r\gh\t ! _w w die f leukemia & bone canc]4 ,f pa/ te/s1 :i* h involv$ ! explosion ( ab\t fifty megatons ( fission en]gy1 ! possibility exi/s t ano!r #ej #bjj1 i4e41 #aj1jjj cases may occur4 ,/ati/ical me?ods are n able to f9d ! diff]5ce betwe5 #f1jjj1jjj & #f1jaj1jjj4 ,!re is no way to diff]5tiate betwe5 ! fall\t-induc$ cases ( leukemia & bone canc]1 & ^? :i* occur naturally4 ,! possible %ort5+ ( t5 ?\s& lives may seem r om9\s4 ,b m]e figures c be mislead+4 ,a bett] way to appreciate ! dang] f fall\t is to comp>e x ) o!r m famili> dang]s4 ,su* a comp>ison c be made ) ! natural backgr\nd ( cosmic rays & radioactivity 9 ! e>? & 9 our own bodies4 ,we are con/antly & inescapably expos$ to ?is radiation4 ,our ance/ors h be5 expos$ to x4 ,! human race has evolv$ 9 su* a radioactive environm5t4 ,moreov]1 ! biological effects f diff]5t k9ds ( radiation c be comp>$ 9 a mean+ful way 9 t]ms ( ro5tg5s4 ,!re=e ! dang] f ,sr is n unkn[n 9 e respect4 ,9 "s ways x is v well-kn[n because we & all liv+ be+s h sp5t our days 9 a simil>ly dang]\s surr\nd+4 ,we live on an e>? :i* has radioactivity 9 its rocks1 :i* c>ries a simil> activity 9 its wat]s1 & :i* is expos$ f all sides1 to a ra9 ( p>ticles :i* produce effects id5tical ) ! effects ( radioactive mat]ials4 ,n all radiations :i* h ! same int5sity 7! same numb] ( ro5tg5s7 h precisely ! same effect4 ,! damage produc$ also dep5ds some:at on ! spac+ ( ! ioniz$ & disrupt$ molecules4 ,! cosmic rays & ! ,sr1 h[ev]1 are q simil> ev5 9 ?is respect4 ,! read] w recall t ! spac+ ( ! ionization dep5ds only on ! *>ge & ! spe$ ( ! ioniz+ p>ticle4 ,! ioniz+ p>ticle f ! ,sr is an en]getic beta ray1 :i* has a *>ge ( "o & a spe$ close to t ( light4 ,a l>ge "p ( ! backgr\nd radiation :i* rea*es our bones comes f ! cosmic rays4 ,! ma9 portion ( ! cosmic rays is due to ! mesons4 ,! meson1 l ! beta ray1 has a unit *>ge & a spe$ close to t ( light4 ,! two p>ticles may !re=e be expect$ to produce id5tical biological effects4 ,! only diff]5ce betwe5 _! effects is t ! beta ray does n h en\gh en]gy to leave ! bones1 :ile ! meson is s en]getic t x deposits its en]gy bo? 9 our bones & ?r\gh\t our :ole body4 ,?us if we comp>e a ,sr dose ) ! same dose ( cosmic rays ! same effect to ! bones mu/ be expect$4 ,b ! cosmic rays give rise to additional effects 9 our bodies4 ,! total backgr\nd dose to ! bones is ab\t #j4ae ro5tg5s p] ye> = ! av]age p]son liv+ at sea level 9 ! ,unit$ ,/ates4 ,( ?is am\nt1 ab\t #j4jce ro5tg5s is due to cosmic rays4 ,at high] altitudes ! cosmic ray dosage increases4 ,9 ,d5v]1 at an altitude ( #ejjj feet1 ! cosmic rays contribute #j4je ro5tg5s p] ye>4 ,! above numb]s %\ld be comp>$ ) ! pres5t level ( _w-wide fall\t radiation to ! bones3 ab\t #j4jjc ro5tg5s p] ye> 7f ,sr & o!r s\rces74 ,! fall\t radiation is ?us only a few p] c5t ( ! natural cosmic radiation4 ,x is small ev5 :5 comp>$ to ! v>iation ( cosmic ray int5sity betwe5 sea level & #ejjj feet4 ,a correlation betwe5 ! frequ5cy ( leukemia & bone canc]1 & ! int5sity ( natural radiation has be5 look$ =4 ,"s /ati/ics = ! ye> #aidg1 be=e weapons te/+ began1 are available4 ,!y %[ ! numb] ( cases ( ^! diseases occurr+ 9 t ye> p] #ajj1jjj population4 ,bone ,canc] ,leukemia ,d5v] #b4d #f4d ,new ,orleans #b4h #f4i ,san ,francisco #b4i #aj4c ,! extra radiation t "o gets 9 ,d5v] f cosmic rays is _m times great] ?an ! fall\t radiation4 ,b ! table %[s no increas$ incid5ce ( bone canc] or leukemia4 ,on ! contr>y--! incid5ce ( ^! diseases is actually l[] 9 ,d5v]4 ,n all ( ! natural backgr\nd radiation is due to cosmic rays4 ,"p ( ! backgr\nd comes f natural radioactive elem5ts 9 ! soil & 9 ! dr9k+ wat]4 ,^! include uranium1 potassium1 ?orium & radium4 ,radium behaves l calcium & /rontium1 & gets deposit$ 9 our bones4 ,all ^! effects are1 to ! be/ ( our k1 at lea/ z int5sive 9 ! ,d5v] area z 9 ,san ,francisco or ,new ,orleans4 ,"o possible explanation = ! l[] incid5ce ( bone canc] & leukemia 9 ,d5v] is t disruptive processes l radiation are n necess>ily h>mful 9 small en\gh doses4 ,cell det]ioration & regr[? g on all ! "t 9 liv+ creatures4 ,a slight accel]ation ( ^! processes c\ld conceivably be b5eficial to ! organism4 ,"o %\ld n =get t :ile radiation c cause canc]1 x has be5 us$ 9 massive doses to ret>d & sometimes ev5 to cure canc]4 ,! reason is t "s canc] cells are m /rongly damag$ by radiation ?an ! normal cells4 ,9 spite ( ! table1 h[ev]1 !re may actually be an increas$ t5d5cy t[>d bone canc] & leukemia t results f liv+ 9 ,d5v]4 ,if s--& ?is is ! ma9 po9t--! effect is too small to be notic$ comp>$ to o!r effects4 ,we mu/ rememb] t ,d5v] diff]s f ,new ,orleans & ,san ,francisco 9 _m ways 7besides altitude71 & ^! diff]5ces may also influ5ce ! /ati/ics4 ,a m ?or\gh consid]ation ( ! backgr\nd radiation gives fur!r evid5ce t ?is radiation is m important ?an ! pres5t or expect$ effects ( ,sr4 ,! radium deposit$ 9 our bones f dr9k+ wat] has be5 obs]v$ to rea* values z high z #j4ee ro5tg5s p] ye>4 ,fur!rmore ! heavi] & sl[] alpha p>ticles emitt$ by radium cause ionization processes :i* occur 9 clos] spac+ & are !re=e m damag+ ?an ! ionization due to ,sr4 ,to make ?+s worse radium is deposit$ 9 our bones 9 little nodules 7hot spots74 ,?us ! possibility ( local damage is enhanc$4 ,! backgr\nd radiation to :i* we are expos$ v>ies = "s unexpect$ reasons4 ,x has be5 po9t$ out rec5tly t brick may conta9 m natural radioactivity ?an wood4 ,! diff]5ce betwe5 liv+ 9 a brick h\se & liv+ 9 a wood h\se c\ld give rise to t5 times z mu* radiation z we are curr5tly gett+ f fall\t4 7,! additional radiation f ! brick might be z mu* z #j4jc ro5tg5s p] ye>47 ,human be+s are subject to radiation n only f natural s\rces1 b also f man-made s\rces4 ,"o ( ^! is we>+ a wri/ wat* ) a lum9\s dial4 ,ano!r is hav+ ,x-rays = m$ical purposes4 ,bo? ( ^! s\rces give mu* m radiation ?an ! fall\t4 ,( all ioniz+ radiation to :i* we are expos$ ! ,x-rays are mo/ important4 ,9 "s cases m$ical ,x-rays h int5sities :i* are noticeably h>mful4 ,yet ?is damage is practically always ( little consequ5ce comp>$ to ! advantage f correct recognition ( any tr\ble t ! ,x-ray discloses4 ,we may summ>ize 9 ?is way4 ,our k ( ! effects f ! fall\t is defici5t4 ,we _c say exactly h[ _m lives may be impair$ or %ort5$4 ,on ! o!r h&1 our k is suffici5t to /ate t ! fall\t effect is bel[ ! /ati/ically obs]vable limit4 ,x is also consid]ably less ?an ! effect produc$ by mov+ f sea level to an elevat$ location l ,d5v]1 :]e cosmic radiation has a great] int5sity4 ,x is also less ?an hav+ a *e/ ,x-ray e ye>4 ,9 o!r words1 we "k en\gh to /ate positively t ! dang] f ! _w-wide fall\t is less ?an _m o!r radiation effects :i* h n worri$ p & d n worry !m n[4 ,we h comp>$ radiation f ! fall\t ) radiation f o!r s\rces4 ,x is also possible & helpful to comp>e ! fall\t dang] ) diff]5t k9ds ( dang]s4 ,= ?is purpose x is conv5i5t to express all dang]s 9 t]ms ( a r$uc$ life-expectancy4 ,= example1 smok+ "o pack ( cig>ettes a day seems to cut "o's life-expectancy by ab\t #i ye>s4 ,?is is equival5t to #ae m9utes p] cig>ette4 ,t cig>ettes are ?is h>mful is1 ( c\rse1 n kn[n ) c]ta9ty4 ,x is a 8be/ guess10 due to ,dr4 ,h>d9 ,jones1 bas$ on an analysis ( /ati/ical data4 ,a numb] ( ,dr4 ,jones' /ati/ical f9d+s are li/$ 9 ! foll[+ table3#ac ,r$uc$ ,life ,expectancy ,be+ #aj p] c5t ov]weight #a4e ye>s ,smok+ "o pack ( cig>ettes a day #i ye>s ,liv+ 9 ! city in/ead ( ! c\ntry #e ye>s ,rema9+ unm>ri$ #e ye>s ,hav+ a s$5t>y job in/ead ( "o involv+ ex]cise #e ye>s ,be+ ( ! male sex #c ye>s ,automobile accid5ts #a ye> ,"o ro5tg5 ( radiation #e to #aj days ,! _w-wide fall\t 7lifetime dose at pres5t level7 #a to #b days ,! read] w see t ! _w-wide fall\t is z dang]\s z be+ an ounce ov]weight or smok+ "o cig>ette e two mon?s4 ,illu/ration3 ,h[ p get radiation ,av]age dose 9 ro5tg5s p] ye> ,! objection may be rais$ t ! fall\t1 :ile n yet dang]\s1 may become s z m nations develop & te/ atomic weapons4 ,on ?is po9t we c only say t ! future is n easy to pr$ict4 ,"s factors1 h[ev]1 ju/ify optimism4 ,we are le>n+ h[ to regulate ! fall\t by explod+ bombs "u prop] surr\nd+s4 ,developm5t ( clean bombs w greatly r$uce ! radioactivity produc$4 ,deep und]gr\nd te/s w elim9ate fall\t altoge!r4 ,! activity put into ! atmosph]e 9 #aied 0 consid]ably great] ?an ! activity releas$ 9 any o!r ye>4 ,x is highly probable t ! activity produc$ by ,unit$ ,/ates te/s w cont9ue to decl9e4 ,f9ally1 we may rem>k t radiation is unspecific 9 its effects4 ,*emicals are specific4 ,ab\t ! effects ( a new +r$i5t 9 our diet1 9 our m$ic9e1 or 9 ! air we brea!1 we "k mu* less ?an we "k ab\t radiation4 ,if we %\ld worry ab\t our ignorance conc]n+ our *emical surr\nd+s z we worry ab\t ! possible effects ( radiation1 we w\ld be condemn$ to a cons]vatism t w\ld /op all *ange & /ifle all progress4 ,su* cons]vatism w\ld be m immobile ?an ! empire ( ! ,ph>aohs4 ,x has be5 claim$ t x is wrong to endang] any human life4 ,is x n m reali/ic & 9 fact m 9 keep+ ) ! ideals ( humanit>ianism to /rive t[>d a bett] life = all mank9d8 ,,*apt] ,,xiii ,dang] to ! ,race ,radiation may hurt ! individual4 ,x may also be h>mful = our *ildr5 & hurt ! race4 ,we h se5 t ! dang] f ! radiation due to te/+ is small comp>$ to _m risks :i* we habitually take & almo/ always ignore1 :i* 9 fact we h to ignore to cont9ue to live 9 ?is civiliz$ _w4 ,9 addition we are n ev5 q sure t ! dang] to ! individual is real4 ,!re c be little d\bt1 h[ev]1 t radiation does produce "s h>mful *anges 9 our *ildr54 ,:at seems ev5 m fright5+1 is t ^! *anges may n %[ up 9 our *ildr5 b only 9 _! *ildr5 or fur!r prog5y4 ,a dang] :i* may lie hidd5 = g5]ations might seem m t]rify+1 especially z x has (t5 be5 repeat$ t all su* radiation effects are h>mful4 ,we transmit our prop]ties to com+ g5]ations 9 a mo/ curi\s & conc5trat$ fa%ion4 ,f ! "m & ! fa!r a *ild inh]its a numb] ( *romosomes1 tw5ty-f\r f ea*4#ad ,^! are /ructures along :i* ! actual c>ri]s ( ! prop]ties--! g5es--are /rung up4 ,we are beg9n+ to und]/& some?+ ab\t ! nature ( ! g5es4 ,!y seem to be v big spiral molecules4 ,!y c>ry ! ma/] plan ( our body & ev5 ( our "* 9 a /range *emical code4 ,! laws ( h]$ity are complicat$ because ( ! fact t ! same prop]ty is influ5c$ by a g5e f ea* p>5t4 ,frequ5tly ^! two g5es dictate diff]5t behavior & !n ! result is a compromise1 sometimes ev5h&$1 sometimes unbalanc$4 ,b ( ! two g5es only "o w f9d its way to ! *ild ( ! next g5]ation4 ,! compromise is tempor>y & orig9al prop]ties may em]ge aga94 ,:i* "o ( any pair ( *romosomes 7or ( ! two assemblies ( g5es7 c>ries on is a matt] ( *ance4 ,9 ! _w ( ! cells z 9 ! _w ( atoms x is *ance t det]m9es ! future--n fate4 ,( all ^! facts we ne$ be p>ticul>ly int]e/$ 9 "o4 ,! units ( inh]itance are r con/ant b n q immutable4 ,!re is a small possibility t any g5e may suff] a mutation4 ,t is1 x may turn into a new *emical1 c>ry+ a new code & new prop]ties4 ,a g5e is an extremely f9ely & precisely con/itut$ object4 ,x mu/ be s 9 ord] to c>ry all ! racial pa/ 9 s little mat]ial4 ,a mutation due to *ance w spoil ?is ord] 9 almo/ e in/ance4 ,! great majority ( mutations are detrim5tal4 ,_m are le?al4 ,x is an incr$ible fact t ^! r&om mutations1 almo/ always h>mful & nev] proce$+ accord+ to any plan1 %\ld h be5 responsible 9 ! v long run = all ! _m beautiful & p]fect liv+ creatures t nature has produc$ 7& ?is includes ! human race74 ,! ?read lead+ f s+le cells to cell colonies1 worms1 fi%es1 v]tebrates1 mammals & human be+s does c]ta9ly n seem to be ! "w ( *ance4 ,mu* less does x seem to be ! "w ( a gamble tak+ "o *ance ( a small improvem5t aga9/ a ?\s& *ances ( de=mity or dea?4 ,nev]!less x is su* a t]rible game ( *ance :i* has produc$ bo? ! human body & 9 "s mann] also ! human _s4 ,big numb]s are /range ?+s & :5 ea* memb] ( a huge assembly mu/ be giv5 individual att5tion !n ! numb]s are ev5 h>d] to appreciate4 ,billions ( contempor>y lives 9 billions ( di/9ct g5]ations h l$ to ! incr$ible outcome3 ! h>mony ( life produc$ by gambl+4 ,radiation is surely disruptive4 ,x does cause mutations4 ,s9ce ! g5es appe> to be s+le molecules1 a s+le process ( ionization or excitation is likely to result 9 a *ange4 ,z has be5 said be=e !re is d\bt :e!r or n canc] & leukemia c be caus$ by exce$+ly little radiation4 ,!re is little d\bt1 h[ev]1 t mutations c be caus$ by any small am\nt ( radiation4 ,! less radiation ! less ! *ance4 ,b ! *ance w always be !re4 ,a v great increase 9 ! natural rate ( mutations c\ld inde$ h t]rify+ effects4 ,we c be q c]ta91 h[ev]1 t radiation f atomic te/s w increase ! *ance ( mutations by only a v small am\nt4 ,! argum5t is ess5tially ! same z ! "o conc]n+ ! dang] to ! individual4 ,! te/s are responsible = #j4jja or #j4jjb ro5tg5s p] ye> to ! human reproductive cells4 ,?is is equival5t to approximately #j4je ro5tg5 p] g5]ation4 ,mo/ ( ?is radiation is due to gamma rays f ,cs :i* has be5 deposit$ on ! gr\nd or absorb$ 9 ! body4 ,! numb] ( mutations caus$ by ?is radiation is to be comp>$ ) ! numb] ( natural mutations4 ,"s ( ! natural mutations are caus$ by heat & *emicals4 ,"s are due to backgr\nd radiation1 to cosmic rays or to gamma & beta rays emitt$ by natural radioactive sub/ances 9 or ne> our bodies4 ,our be/ e/imate is t #aj p] c5t ( ! natural mutations are due to ! backgr\nd radiation4 ,ov] a p]iod ( "o g5]ation ! backgr\nd radiation dosage to ! human reproductive cells is approximately five ro5tg5s4 ,assum+ a simple proportionality betwe5 dosage & ! numb] ( mutations1 x foll[s t fifty ro5tg5s w\ld be requir$ to induce a numb] ( mutations equal to ! total numb] ( natural mutations 7f backgr\nd radiation & all o!r causes74 ,t is1 fifty ro5tg5s is a 8d\bl+ dose40 ,! atomic te/s are !re=e increas+ ! numb] ( mutations by ab\t #j4je #ej1 :i* is #j4a p] c5t4 ,?is k9d ( increase 9 ! rate ( mutations w\ld c]ta9ly n seem to be a s]i\s reason = worry4 ,actually ! numb] ( mutations f ! te/s is v small ev5 comp>$ to geographical & altitude v>iations 9 ! natural radioactivity4 ,! ,inca empire exi/$ = _m g5]ations 9 ! high c\ntry ( ,p]u4 ,! p ( ,tibet h be5 expos$ = g5]ation aft] g5]ation to ! great] cosmic ray int5sity :i* bomb>ds !m ?r\gh a ?9n] lay] ( atmosph]e4 ,^! p h be5 expos$ to mu* great] additional radiation ?an any?+ :i* is caus$ by atomic te/s4 ,yet g5etic diff]5ces h n be5 notic$ 9 ! human race or = t matt] 9 any o!r liv+ species 9 ,p]u or ,tibet4 ,we are c]ta9ly talk+ "h ab\t que/ions :i* may /rike h>d on "s individuals b :i* f ! po9t ( view ( ! community or race are n s]i\s4 ,x has be5 (t5 repeat$ t all mutations due to radiation are h>mful4 ,!re is e reason to believe t mutations due to radiation are n diff]5t 9 k9d f o!r mutations4 ,%\ld we !n s]i\sly believe t all mutations are h>mful8 ,t mo/ ( !m are is admitt$4 ,if all ( !m 7 inde$ always h>mful1 we mu/ d5y ! simple/ facts ( evolution4 ,!re w be "s :o ma9ta9 t ! human race is n capable ( improvem5t4 ,su* an argum5t is irrefutable4 ,x is also unreasonable4 ,:at _c be fur!r improv$ is p]fect1 & n _m p w ma9ta9 t our species c claim p]fection4 ,ano!r & mu* m plausible argum5t has be5 advanc$3 ,9 ! wild /ate liv+ species d p]fect !mselves by means ( natural selection4 ,human society by c>+ = ! imp]fect & defective individual has elim9at$ natural selection4 ,!re=e fur!r mutations w n improve mank9d4 ,x is v h>d to discuss ?is "q = ! simple reason t ! argum5t involves ! int]action ( two processes extremely diff]5t 9 magnitude & 9 fact diff]5t 9 k9d4 ,on ! "o h& x conc]ns itself ) evolution :i* proce$s 9 ! sl[ delib]ate way ( a glaci]4 ,on ! o!r h& x focuses att5tion ^u ! process ( human civilization ) its te*nical & social *anges :i* has ga9$ mom5tum l an avalan*e4 ,! mom5tum is /ill !re & x is /ill increas+ & :]e we %all l& we d n "k4 ,to consid] ! motion ( ! glaci] :ile be+ c>ri$ along by ! avalan*e puts ?+s completely out ( proportion4 ,long be=e ! pres5t rates ( mutation c\ld h any effect ^u ! human species we %all live 9 a v diff]5t _w & we %all h />t$ to influ5ce our own behavior includ+ ^? ( selection1 natural or o!rwise1 9 ways :i* today we _c =esee4 ,if we discuss ! "q h[ civilization w influ5ce natural selection1 we %all n d x ) ! hope ( arriv+ at a firm answ]4 ,we %all d x r 9 ord] to illu/rate h[ d\btful all ! argum5ts are :i* conc]n ! int]play ( two processes :i* _c be measur$ 9 ! same scale4 ,x is true t we c & d pres]ve ! lives ( *ildr5 :o1 because ( inh]it$ weaknesses1 w\ld p]i% "u natural conditions4 ,x is true too t we d ?is = reasons & = feel+s conc]n+ ! individual & we d x )\t reg>d to ! consequ5ces to ! race4 ,h[ev]1 "u our pres5t condition ( civilization a disease :i* c be correct$ by adm9i/]+ *emicals or us+ ! surgeon's knife is no long] effectively a disease4 ,9 our pres5t condition su* a life c be z valuable to society & to ! race z a life :i* does n h ^! sup]ficial %ortcom+s4 ,t we c & d pres]ve m life 9 ?is mann] only emphasizes t "u pres5t conditions biological diff]5ces :i* us$ to be important no long] matt]4 ,on ! o!r h&1 9 social liv+ _m prop]ties :i* us$ to be indiff]5t = a wild be+ h become ( great significance4 ,ability to communicate & to get along ) our fell[s is n ! only "o1 b is p]haps ! mo/ obvi\s "o ( su* prop]ties4 ,! /ruggle = exi/5ce has become m g5tle1 & ! *ance ( any individual to live on 9 8 *ildr5 is gov]n$ by new ways ( behavior4 ,nev]!less ! diff]5ce betwe5 ! individual adapt$ to civiliz$ liv+ & ! "o :o is n adapt$ is ( great importance & w become ( great] importance4 ,x is likely t civilization w n elim9ate evolution ( ! race4 ,r x w direct x into new pa?s4 ,b ! greate/ *ange might be expect$ f an entirely diff]5t direction4 ,we are go+ to und]/& 9 real detail ! intricacies ( human inh]itance4 ,!n we %all be fac$ ) problems & %all f9d possibilities ( an entirely new & diff]5t k9d4 ,! int]e/ ( a p]son 9 8 *ildr5 is n a sup]ficial "o4 ,x is "o ( ! mo/ /rong & la/+ =ces 9 biology1 sociology & hi/ory4 ,a cle> und]/&+ ( ! details ( inh]itance may br+ ab\t "s grave difficulties because a new situation is nev] fitt$ easily into exi/+ patt]ns ( liv+4 ,9 ! end m und]/&+ may br+ ab\t improvem5ts ( a k9d beside :i* all ! wor?:ile ?+s t h be5 s f> accompli%$1 might look unimportant4 ,! real importance ( radioactivity = h]$ity does n lie 9 ! fact t we may spe$ up ! glaci] by "o in* 9 a mill5nium4 ,! real importance ( nucle> radiation is r t x is help+ u to und]/& ! /range processes ( life & ! curi\s sub/ances :i* connect "o g5]ation to ! next4 ,,*apt] ,,xiv ,! ,cobalt ,bomb ,nucle> explosions seem horrible = _m reasons4 ,!y 7 pres5t$ to an unprep>$ _w z a dramatic surprise--z ! climax to ! slaught] ( ! ,second ,_w ,w>4 ,_! p[] ( de/ruction is fanta/ic4 ,be=e we _h adju/$ our ?9k+ to atomic bombs1 an ev5 m pot5t tool ( w>f>e--! hydrog5 bomb--0 inv5t$4 ,wor/ ( all3 ,to ! fe> ( de/ruction !re 0 add$ ! dread ( ! unkn[n4 ,x is n surpris+ t discussion ( nucle> weapons has n proce$$ on a purely rational level4 ,to ! nightm>e ( ! atomic & hydrog5 bombs has be5 add$--n z a reality b z a fur!r ?reat--! cobalt bomb4 ,! idea ( su* a bomb is to int5sify ! mo/ t]rify+ aspect ( nucle> explosions3 ! radioactivity4 ,?is radioactivity c\ld be us$ to poison ! enemy4 ,x c\ld get out ( h& & poison ev]yone4 ,cobalt is a radioactive isotope ( ! fairly common metal cobalt4 ,x c be easily produc$ by absorb+ sl[ neutrons 9 ! natural & /able cobalt4 ,x has a half-life ( five ye>s & x emits p5etrat+ gamma rays4 ,^! prop]ties make x useful 9 canc] !rapy4 ,_m canc]\s gr[?s are m s5sitive to radiation ?an heal?y tissue4 ,!re=e radiation c be us$ to r$uce--sometimes ev5 to de/roy--dang]\s tumors4 ,! p5etrat+ rays ( cobalt c rea* ! canc] ev5 deep inside ! human body4 ,! lifetime ( cobalt is long en\gh s t ?is sub/ance is easily in/all$ 9 hospitals4 ,b ! same prop]ties :i* make cobalt useful also make x pot5tially dang]\s4 ,a nucle> explosion produces _m neutrons & ^! c\ld be absorb$ 9 ord9>y cobalt4 ,! radioactivity produc$ 9 ?is way lives long en\gh to become widely di/ribut$4 ,its ray c easily p5etrate a foot ( masonry & sev]al hundr$ feet ( air4 ,a cobalt bomb w\ld inde$ be a mo/ unpleasant object4 7,see pictures #g & #h47 ,"o widely discuss$ possibility is t future nucle> te/s w be us$ to develop a cobalt bomb or o!r bombs = radiological w>f>e4 ,actually te/s h little to d ) ! cobalt bomb4 ,once "o has a p[]ful nucle> weapon1 su* z a hydrog5 bomb1 x is relatively easy to make a radiological bomb4 ,fur!r te/s are n necess>ily requir$4 ,to ! ext5t t any te/+ ne$ be c>ri$ out1 x is only necess>y to activate a mod]ate am\nt ( sub/ance to f9d out 9 :at way a c]ta9 bomb w\ld function z a tool ( radiological w>f>e4 ,te/s ( ?is k9d w\ld add only a negligible am\nt ( radioactivity to ! atmosph]e4 ,!re=e1 9 connection ) ! te/ program we ne$ n worry ab\t ! cobalt bomb or any relat$ exp]im5t4 ,! "q ( ! cobalt bomb or radiological w>f>e 9 g5]al is n :e!r x is feasible--x is--b r :e!r x s]ves a useful milit>y purpose4 ,x is n impossible t situations might arise 9 :i* radiological w>f>e c\ld be milit>ily advantage\s4 ,in/ead ( cobalt1 o!r mat]ials may be plac$ ne> ! nucle> bombs4 ,9 ?is way o!r radioactive sub/ances c be produc$4 ,by an appropriate *oice ( su* a sub/ance "o c get a radioactive mat]ial :i*1 :5 deposit$ ne> ! po9t ( explosion1 w contam9ate ! site = a "t :i* c be adju/$ to ! milit>y requirem5ts4 ,! lifetime ( ! radioactive mat]ial may be long en\gh to give an opportunity to ! p to escape f ! contam9at$ area4 ,at ! same "t1 "o may precipitate almo/ all ! activity ne> ! explosion s t di/ant localities w\ld n be s]i\sly affect$4 ,x is conceivable1 !re=e1 t radiological w>f>e c\ld be us$ 9 a humane mann]4 ,by explod+ a weapon ( ?is k9d ne> an isl& "o might be able to =ce evacuation )\t loss ( human life4 ,no in/rum5t1 n ev5 a weapon1 is evil 9 itself4 ,ev]y?+ dep5ds on ! way 9 :i* x is us$4 ,public op9ion has all b p]suad$ itself t nucle> weapons w be us$ n = a milit>y objective b to t]rorize & kill ! greate/ numb] ( p4 ,?is is te*nically feasible4 ,9 fact1 x does n ev5 require ! atomic bomb4 ,= ! la/ hundr$ ye>s ?is possibility has be5 ) u4 ,bact]iological w>f>e may cause widespread de/ruction4 ,yet no "o has resort$ to ?is horrible way ( mak+ w>4 ,we d n believe t anyone w expose 8 enemy & ultimately himself to indiscrim9ate bact]iological or radiological de/ruction4 ,our gu>antee aga9/ ?is dang] is n t x _c be done4 ,our gu>antee is ! bett] & san] "p ( human nature3 ! w to survive & ! feel+ ( common dec5cy4 ,,*apt] ,,xv ,:at ,ab\t ,future ,te/s8 ,_m p feel t te/s %\ld be discont9u$4 ,?is feel+ is widespread & /rong4 ,! "q ( te/s is obvi\sly important4 ,x may influ5ce our security z individuals4 ,x c]ta9ly w influ5ce our security z a nation4 ,if 9 a free1 democratic c\ntry ! majority believes t some?+ %\ld be done--x w be done4 ,! sov]eign p[] 9 a democracy is 8! p40 ,x is ( ! greate/ importance t ! p %\ld be hone/ly & completely in=m$ ab\t all relevant facts4 ,9 no o!r way c a s\nd decision be rea*$4 ,! basic & relevant facts are simple4 ,! /ory c be pres5t$ )\t unnecess>y frills or undue emotion4 ,:5 ?is has be5 done1 ! "r decision w be rea*$ by common s5se r ?an by exceptional clev]ness4 ,un=tunately mu* ( ! discussion ab\t cont9u$ exp]im5tation ) nucle> explosives has be5 c>ri$ out 9 a mo/ emotional & confus$ mann]4 ,"o argum5t conc]n+ te/s is s fanta/ic t x des]ves to be m5tion$ = t v reason3 ,x has be5 claim$ t nucle> explosions may *ange ! axis ( ! e>?4 ,( c\rse1 nucle> explosions d produce su* *anges4 ,only ! *anges are s small t !y are impossible to obs]ve & ev5 difficult to e/imate4 ,se>*+ = effects connect$ ) pa/ te/s t may displace ! axis ( ! e>?1 or ! position ( ! ,nor? ,pole1 we c\ld f9d no effect t w\ld h caus$ a *ange ( position ev5 z great z ! size ( an atom4 ,"o c\ld design te/s ) ! specific purpose to produce su* a *ange1 b ^! man-made effects c\ld n be comp>$ ev5 remotely ) ! =ces ( nature4 ,! motion ( ! ,gulf ,/ream has a small effect on ! ,nor? ,pole2 b ?is effect is incomp>ably great] ?an :at any nucle> explosion c\ld accompli%4 ,x is good to "k t ! old top on :i* we live does h "s /ability4 ,! argum5t ab\t _w-wide radioactive fall\t is m s]i\s4 ,x is ass]t$ t fall\t is dang]\s & t we are ignorant ( ! ext5t ( ! dang]4 ,9 a n>r[1 lit]al s5se bo? ^! /atem5ts are correct4 ,b 9 ! prec$+ *apt]s we h se5 t ! dang] is limit$4 ,we d n "k precisely h[ great x is4 ,we d "k1 h[ev]1 t ! dang] is consid]ably small] ?an ! dang] f o!r radiations to :i* we cont9ue to expose ourselves )\t worry4 ,! dang] f ! te/s is q small comp>$ ) ! effects ( ,x-rays us$ 9 m$ical practice4 ,! fall\t produces only a fraction ( ! increase 9 cosmic ray effect to :i* a p]son subjects himself :5 he moves f ! sea%ore to a place ( high] altitude l ,colorado4 ,p may or may n be damag$ by ! fall\t4 ,b x is q c]ta9 t ! damage is f> bel[ a level ( :i* we usually take notice4 ,fall\t 9 ! vic9ity ( ! te/ sites did cause damage4 ,9 ! pa/ ?is damage 0 n great al?\gh 9 "o ,pacific te/ x 0 s]i\s4 ,precautions h be5 increas$ & we may hope t future accid5ts w be avoid$ altoge!r4 ,! safety record ( ! ,atomic ,en]gy ,commission comp>es favorably ) o!r ent]prises ( simil> scale4 ,x seems probable t ! root ( ! opposition to fur!r te/s is n connect$ ) fall\t4 ,! root is deep]4 ,! real reason aga9/ fur!r te/s is connect$ ) our desire = dis>mam5t & = peace4 ,!re c be no d\bt t ! desire = peace is mo/ deep1 & ?is desire is felt by all ?9k+ & hone/ p on our e>?4 ,all ( u c]ta9ly hope t ! cata/rophe ( w> c be avoid$4 ,?is great & univ]sal wi% = peace is ! driv+ =ce beh9d ! desire = dis>mam5t4 ,9 ! m9ds ( mo/ p x w\ld be an important /ep t[>d dis>mam5t if ! te/+ ( nucle> weapons 7 /opp$ by all nations4 ,?is belief is widely held1 b x is n necess>ily well-f\nd$4 ,9 fact1 !re are argum5ts on ! o!r side :i* %\ld be consid]$ c>efully4 ,x is g5]ally believ$ t ! ,fir/ ,_w ,w> 0 caus$ by an arms race4 ,= "s /range reason mo/ p =get t ! ,second ,_w ,w> 0 br\ght ab\t by a situation :i* c\ld be call$ a race 9 dis>mam5t4 ,! peace-lov+ & p[]ful nations dive/$ !mselves ( _! milit>y p[]4 ,:5 ! ,nazi regime 9 ,g]many adopt$ a program ( rapid prep>ation = w>1 ! re/ ( ! _w 0 caught unaw>es4 ,at fir/ !y did n want to accept ! fact ( ?is m5ace4 ,:5 ! dang] 0 unmi/akable1 x 0 too late to av]t a mo/ cruel w>1 & almo/ too late to /op ,hitl] %ort ( _w conque/4 ,un=tunately1 dis>mam5t is safe only :5 no "o wants to impose 8 w by =ce ( arms ^u 8 neighbors4 ,9 ! uneasy _w 9 :i* we live today no reasonable p]son w advocate unilat]al dis>mam5t4 ,:at p hope is t all sides w agree to r$uce _! milit>y p[] & !reby contribute to a m peaceful atmosph]e4 ,! elim9ation ( te/s has appe>$ possible & prop] = two reasons4 ,"o is t te/s are conspicu\s1 & !re=e x is believ$ t we c *eck :e!r or n te/+ has actually be5 /opp$ by ev]yone4 ,! second reason is t nucle> explosives already repres5t su* t]rify+ p[] t fur!r te/s appe> useless & irrational4 ,^! argum5ts are simple & almo/ univ]sally accept$4 ,!y are bas$ on misconceptions4 ,a nucle> explosion is a viol5t ev5t1 b 9 ! great expanses ( our globe su* te/s c be effectively hidd5 if appropriate c>e is tak5 to hide !m4 ,!re c be no d\bt t ?is is possible4 ,! "q is only h[ mu* x co/s to hide a te/ & h[ big is ! explosion t c be c>ri$ out 9 secret = a c]ta9 am\nt ( exp5diture4 ,if an agreem5t 7 made to discont9ue ! te/s1 ! ,unit$ ,/ates w\ld surely keep su* an agreem5t4 ,! v social & political /ructure ( our c\ntry excludes ! possibility t _m p w\ld collaborate 9 break+ an int]national und]tak+4 ,:e!r ,russia w\ld or w\ld n keep su* an agreem5t w\ld dep5d on ! +5uity ( ! ,russians1 on _! will+ness to make economic sacrifices1 & on _! hone/y4 ,( ^! ?ree factors we c h a firm op9ion ab\t ! fir/4 ,! ,russians are c]ta9ly +5i\s en\gh to devise secret me?ods ( te/+4 ,z to ! o!r que/ions1 :e!r ! ,russians w want to inve/ ! ef=t & :e!r !y w be b\nd by _! ^w1 we feel t ea* man is entitl$ to 8 own op9ion4 ,accord+ to pa/ exp]i5ce1 an agreem5t to /op te/s may well be foll[$ by secret & successful te/s beh9d ! iron curta94 ,9 a m g5]al way we may ask ! "q3 ,is x wise to make agreem5ts :i* hone/y w respect1 b di%one/y c circumv5t8 ,%all we put a free1 democratic gov]nm5t at a disadvantage comp>$ to ! absolute p[] ( a dictator%ip8 ,%all we introduce prohibition 9 a new =m1 j to give rise to bootlegg+ on a mu* great] scale8 ,x is almo/ c]ta9 t 9 ! competition betwe5 prohibition & bootlegg+1 ! bootlegg] w w94 ,all ( ^! argum5ts1 h[ev]1 w\ld become irrelevant if x 7 true t fur!r te/+ w\ld n accompli% any fur!r desirable result4 ,x has be5 said & (t5 repeat$ t we n[ possess adequate nucle> explosives to wipe out ! cities ( any enemy4 ,:at m d we ne$8 ,our ma9 purpose 9 fur!r exp]im5tation ) nucle> bombs is n1 ( c\rse1 to make city-bu/]s m horrible4 ,we w\ld pref] n to h to use our nucle> weapons at all4 ,we keep !m z a c\nt]?reat aga9/ ! dang] t we ourselves %\ld be subject$ to a deva/at+ attack4 ,to und]/& :at we are actually try+ to d 9 ! te/s1 we h to take a clos] look at "s milit>y problems4 ,9 ! ,second ,_w ,w> /rategic bomb+ 0 us$ = ! fir/ "t on a really massive scale4 ,x may well be &1 9 fact1 x is probable t su* /rategic bomb+ w n be repeat$ 9 ! future4 ,!re are two milit>y reasons = ! bomb+ ( cities4 ,"o is t factories are locat$ 9 cities1 & ^! factories support ! w> ef=t4 ,! o!r reason is t cities are c5t]s ( transportation ?r\gh :i* ! supplies ( w> mat]ials pass4 ,by de/roy+ ^! c5t]s ! fl[ ( ! w> supplies c be int]rupt$4 ,nucle> w>f>e is likely to be q diff]5t f pa/ conflicts4 ,! great conc5tration ( firep[] :i* a nucle> weapon repres5ts makes x possible to attack on enemy any:]e1 at v %ort notice4 ,?is is true no matt] :at ! p>ticul> t>get is1 :e!r "o is try+ to attack ! planes1 %ips1 tanks1 or troop conc5trations ( an enemy4 ,! great mobility ( nucle> firep[] makes x highly probable t ! nucle> conflict w be %ort4 ,:at ! factory produces dur+ ?is conflict w n affect ! outcome ( ! fight+4 ,! only weapons on :i* anyone c rely are ! weapons :i* are already /ockpil$4 ,!re=e1 x w be milit>ily useless to bomb factories4 ,! same fact ( mobility also implies t no great fl[ ( w> mat]ial w ne$ to be ma9ta9$4 ,practically all movem5t c be execut$ by light & fa/ me?ods1 by planes1 subm>9es1 & small battle gr\ps4 ,"u ^! conditions ! cities w lose _! importance z c5t]s ( transportation4 ,! only purpose 9 bomb+ cities w be to spread t]ror among ! enemy4 ,?is 0 r>ely done 9 pa/ w>s4 ,9 fact1 t]ror is self-defeat+ because x provokes retaliation f ! o!r side4 ,we believe t ! role ( nucle> weapons 9 a future w> is by no means ! kill+ ( millions ( civilians4 ,x is r to /op ! arm$ =ces ( an aggressor4 ,?is is n easy to d because x requires n only nucle> weapons1 b v special k9ds ( nucle> weapons :i* are h>d to develop & h>d] to p]fect4 ,b ) prop] exp]im5tation & prop] plann+ ! def5sive use ( nucle> weapons is possible4 ,! idea ( tactical nucle> weapons is n new4 ,! possibility ( us+ nucle> explosives 9 small w>s has be5 frequ5tly discuss$4 ,:at k9d ( weapons d we ne$ 9 ord] to fight ^! small w>s & to def5d ! fre$om ( p :]ev] su* def5se becomes necess>y8 ,x has (t5 be5 sugge/$ t 9 small w>s1 small weapons w be us$1 :ile big weapons are appropriate = big w>s4 ,su* a /atem5t is mu* too simple & has no relation to reality4 ,9 e case ! "r k9d ( weapon is ! "o :i* p]=ms ! job ( /opp+ ! enemy's arm$ =ces )\t inflict+ unnecess>y loss on ! innoc5t by/&]4 ,= ?is purpose we ne$ a great numb] ( weapons :i* are adaptable to specific purposes1 :i* are easy to transport & easy to deliv]1 & give rise to ! k9d ( effect :i* ! situation requires4 ,= in/ance1 a nucle> weapon may be c>ri$ by a fight] plane & us$ to %oot d[n an attack+ bomb]4 ,s9ce ! c>ry+ capacity ( ! fight] plane is sev]ely limit$1 ! weapon = ?is purpose mu/ be small & light4 ,a major objective ( ! te/ program is to develop su* purely def5sive weapons4 ,! enc\nt] betwe5 ! fight] plane & ! bomb] may well take place 9 our own c\ntry ov] populat$ areas4 ,?is possibility w\ld fill mo/ p ) al>m le/ ! population und]nea? ! explosion %\ld be hurt4 ,=tunately1 9 a rec5t nucle> te/ 9 ,nevada1 five well-in=m$ & c\rage\s ,air ,=ce (fic]s demon/rat$ t !re is complete safety to p on ! gr\nd4 ,!y did ?is by /&+ directly b5ea? ! explosion at gr\nd z]o4 ,?is important te/ took place only a few mon?s ago--on ,july #ai1 #aieg4 ,an ,f-#hi jet fight] plane fly+ at #ai1jjj feet above sea level deliv]$ an air-to-air atomic rocket to a preassign$ po9t 9 ! sky4 ,! gr\nd z]o m5 7 #ae1jjj feet imm$iately bel[4 ,!y wore no helmets1 no sun-glasses1 & no protective clo?+4 ,at ! in/ant ( ! explosion ! m5 look$ up1 saw ! fireball & felt ! heat4 ,!re 0 no discom=t1 only a g5tle w>m?4 ,!n !y wait$ = ! %ock wave to arrive--approximately t5 seconds4 ,:5 ! %ock came1 x 0 actually j a l\d noise4 ,h[ev]1 "o ( ! m5 duck$ 8 head in/9ctively4 7,see pictures #i & #aj47 ,! bla/ & ! !rmal pulse 7 ov]4 ,b ! ,air ,=ce m5 /ood _! gr\nd4 ,"o "q /ill rema9$3 ,w\ld !re be any fall\t8 ,!y *eck$ _! radiation in/rum5ts & wait$ :ile ! cl\d drift$ sl[ly away4 ,!re 0 no significant rise 9 ! radiation level4 ,! te/ _h be5 a complete success4 ,! effects ( ! explosion 7 utt]ly insignificant on ! gr\nd4 ,b high 9 ! air an enemy plane c\ld h be5 demoli%$ ev5 if ! nucle> explosion _h miss$ x by a consid]able di/ance4 ,9 ord] t nucle> weapons %\ld be effective aga9/ arm$ invad]s1 x is cle> t great numb]s ( ^! weapons are ne$$4 ,su* great numb]s ( weapons1 "s ( :i* mu/ be gr\nd-bur/1 w produce a consid]able am\nt ( radioactive contam9ation1 & ?is contam9ation w endang] fri5d & foe alike4 ,9 p>ticul>1 ! radioactivity is likely to kill p 9 ! v c\ntry ^: lib]ty we are try+ to def5d4 ,= ?is reason x is mo/ important t we %\ld be able to use nucle> weapons :i* cause ! lea/ possible contam9ation4 ,9 rec5t nucle> te/s m & m att5tion has be5 paid to ! developm5t ( su* clean weapons1 & mo/ =tunately ^! ef=ts are well on ! way t[>d success4 ,! radioactive fall\t f nucle> te/+ gives rise to a possible dang] :i* is q limit$ 9 size4 ,! dang] f ! fall\t 9 a nucle> w>1 h[ev]1 w\ld be real & great4 ,if we /op te/+ n[1 & if we %\ld fail to develop to ! fulle/ possible ext5t ^! clean weapons1 we %\ld unnecess>ily kill a great numb] ( noncombatants4 ,n to develop ! explosives ) ! smalle/ radioactive fall\t w\ld1 inde$1 be completely inexcusable4 ,! only alt]native is t nucle> weapons %\ld n be us$ at all4 ,s9ce ^! weapons h be5 pres5t$ z purely evil in/rum5ts1 mo/ p hope t !y w nev] be us$1 & inde$ "o %\ld hope t w>s1 & !re=e ! use ( ^! weapons1 c be avoid$4 ,b 9 our conflict ) ! p[]ful communi/ic c\ntries :i* /rive = _w dom9ation1 x may be too mu* to hope = un9t]rupt$ peace4 ,if we ab&on our light & mobile weapons1 we %all enable ! ,r$ bloc to take ov] "o c\ntry aft] ano!r1 close to _! bord]s1 z opportunities arise4 ,! free nations _c ma9ta9 ! massive armies ?r\gh\t ! _w :i* w\ld be requir$ to resi/ su* piecemeal aggression4 ,on ! o!r h&1 ! flexible p[] ( clean nucle> explosives w\ld put u 9 a position :]e we c\ld resi/ aggression 9 any "p ( ! _w1 practically at a mom5t's notice4 ,! ann\nc$ policy ( our c\ntry is to ma9ta9 peace & /ability 9 ! _w4 ,by be+ pati5t & prep>$ we are try+ to arrive at a _w ord] bas$ on law & ju/ice = all peoples4 ,!re is no d\bt t ?is policy is support$ by ! ov]:elm+ majority ( ,am]icans4 ,our arm$ =ces ne$ ! greate/ possible flexibility 9 ord] to give /r5g? to ?is policy4 ,su* flexibility we c possess only if we h 9 our possession ! /ronge/1 be/ develop$ weapons :i* are also ! cleane/1 s t !y may be us$ = def5se r ?an = r&om de/ruction4 ,if we r5\nce nucle> weapons1 we op5 ! door to aggression4 ,if we fail to develop clean explosives1 we expose p to disa/] f radioactive fall\t 9 any s]i\s milit>y conflict4 ,to our way ( ?9k+ ^! are weighty argum5ts 9 favor ( cont9u$ exp]im5tation & developm5t ( nucle> weapons4 ,b /ill ano!r1 m g5]al1 po9t ( view %\ld be consid]$4 ,! spectacul> developm5ts ( ! la/ c5turies1 9 sci5ce1 9 te*nology1 & 9 our ev]yday life1 h be5 bas$ on "o important premise3 to explore fe>lessly any consequ5ces to :i* great] k & improv$ skills c lead u4 ,:5 we talk ab\t nucle> te/s1 we h 9 m9d n only milit>y prep>$ness b also ! execution ( exp]im5ts :i* w give u m insight & m ability to control ! =ces ( nature4 ,!re are _m specific political & milit>y reasons :y su* exp]im5ts %\ld n be ab&on$4 ,!re also exi/s ?is v g5]al reason--! tradition ( explor+ ! unkn[n4 ,we c foll[ ?is tradition1 & we c at ! same "t be increas+ly c>eful t radioactivity1 c>elessly disp]s$1 %\ld n int]f]e ) human life4 ,,*apt] ,,xvi ,has ,some?+ ,happ5$ to ! ,wea!r8 ,! wea!r is no long] q z unpr$ictable z x us$ to be4 ,yet we are h>dly ev] sure ( x ev5 a few h\rs 9 advance4 ,"o week is ab\t ! limit ( ! p]iod ( any pr$iction4 ,:]e ! be/ m5 lack k untrammel$ fantasy has a field day4 ,wea!r has s f> rema9$ a safe topic ( conv]sation & ( speculation4 ,nucle> explosions h1 ( c\rse1 be5 made responsible = ! wea!r--= any k9d ( unusual wea!r4 ,be x ra9 or dr\ght or a h>d season ( hurricanes--! nucle> te/s are dragg$ 94 ,! wea!r bureau says3 no4 ,b !n--! wea!r bureau has n always be5 correct4 ,inde$ x w\ld be a miracle if ! popul> talk & ! popul> press w\ld n h se5 "s connection betwe5 atomic explosions & ! wayw>d behavior ( ! seasons4 ,9 "o case--& to our k only 9 "o case--!re has occurr$ a *a9 ( ev5ts />t+ ) a nucle> te/ & end+ 9 a copi\s & unusual d[np\r4 ,9 ! spr+ ( #aiee a te/ %ot ( mod]ate size 0 fir$ 9 ,nevada4 ,at ! same "t ! la/ /orm ( ! season 0 bl[+ itself out 9 ,cali=nia4 ,accord+ to ! usual rules ( meteorology ! radioactive cl\d %\ld h be5 c>ri$ ea/ by ! /eady we/]ly w9ds :i* bl[ ov] ! temp]ate zone4 ,b ?is "t ! cl\d 0 caught up by ! swirl ( ! dy+ ,cali=nia /orm & "s ( ! radioactivity 0 c>ri$ to ! we/ coa/4 ,h\rs aft] ! explosion radioactive ra9 began to fall 9 ,cali=nia4 ,! activity 0 weak en\gh & did n give rise to any worry4 ,b a rem>kable ?+ happ5$4 ,z ! active cl\d arriv$ ov] ,cali=nia ! /orm reviv$4 ,x develop$ into an abundant ra9 :i* is n usual at t place & "t4 ,did we--q un9t5tionally--d some?+ ab\t ! wea!r8 ,! wea!r bureau said3 no4 ,"o mu/ c]ta9ly admit t ?is s+le case proves no?+4 ,only greatly improv$ me?ods ( wea!r obs]vation & wea!r pr$iction w\ld make x possible to decide if su* a *a9 ( ev5ts consi/s ( ! /rong l9ks ( cause & effect or else ( a simple sequ5ce ( haphaz>d occurr5ces4 ,ev5 ?\gh our k is incomplete !re is at lea/ "o simple fact :i* %\ld be borne 9 m9d4 ,all ! en]gy 9 t ,nevada explosion 0 n q suffici5t to evaporate ! wat] droplets 9 a cl\d "o mile broad1 "o mile wide1 & "o mile deep4 ,?is is n a v big ra9 cl\d4 ,su* a cl\d w\ld give ab\t "o ?ird ( an in* ( ra9 wat] ov] "o squ>e mile--n an impressive am\nt4 ,ev5 ! bigge/ hydrog5 bomb w\ld give only en]gy en\gh to evaporate a cl\d t5 miles by t5 miles & t[]+ to ! top ( ! 8boil+0 portion ( our air1 :i* we call ! troposph]e4 ,?is w\ld give r\ghly ?ree in*es ( ra9 ov] a hundr$ squ>e miles--a m impressive am\nt b vani%+ 9 ! va/ness ( ! ,pacific ,ocean4 ,nucle> explosions are viol5t en\gh4 ,b comp>$ to ! =ces ( nature--comp>$ ev5 ) ! daily release ( en]gy f n p>ticul>ly /ormy wea!r--all our bombs are puny4 ,(fh& "o might guess t our nucle> fireworks c\ld n sw+ ! scales 9 ! massive en]gy *anges t we see ar\nd u 9 ! common occurr5ces ( w9d & ra94 ,b ! int]play ( cl\ds & sun%9e1 ( wat] evaporat+1 freez+1 dropp+ & ?aw+--9 %ort ! vag>ies ( wea!r--are bo? involv$ & tricky4 ,small causes c give rise to big effects4 ,"s processes ( air masses sweep+ ov] oceans & cont95ts are irresi/ible & pr$ictable4 ,o!rs1 l ! fir/ upsurge ( hot air f ! ov]heat$ gr\nd1 may be a "q ( close competition & trigg] action4 ,?is is :at makes x s difficult to pr$ict ! wea!r4 ,"o ( ! mo/ delicate processes we mu/ ?9k ab\t is ! =mation ( wat] droplets4 ,:5 "s wat] molecules are mix$ ) air molecules1 we h moi/ air4 ,if su* air rises1 exp&s & cools1 ! wat] molecules lose "s ( _! agitat$ motion & h a great] t5d5cy to /ick toge!r to =m droplets4 ,b x is n easy to get !m />t$ on ?is jo9t ent]prise4 ,if two or ?ree molecules /ick toge!r1 !y soon are %ak5 ap>t4 ,if1 h[ev]1 two or ?ree doz5 are collect$1 ?is is en\gh to />t a gr[? :i* ends 9 a droplet ( wat]4 ,if moi/ air is cool$1 droplets w =m1 provid$ !re is a meet+ place f :i* ! gr[? c />t4 ,if !re is no su* meet+ place1 !re are no droplets & we get no cl\d4 ,if !re are few meet+ places1 ea* w collect a r great am\nt ( wat]1 we w get big drops1 & we may get ra94 ,if !re is an abundance ( meet+ places _m t9y droplets are =m$ :i* w rema9 susp5d$ z a cl\d4 ,! pres5t attempts at ra9-mak+ are connect$ ) a bir?-control ( droplets4 ,we h se5 e>li] t 9 ea* radioactive decay *>g$ p>ticles are emitt$4 ,z ^! move along _! pa?s1 !y te> up m atoms & leave 9 _! wake an assembly ( *>g$ p>ticles4 ,^! *>g$ p>ticles /rongly attract ! molecules ( wat]4 ,!y attract ! molecules ( air mu* less4 ,! reason is t 9 a wat] molecule positive & negative *>ges are sep>at$ to a consid]able ext5t :]eas 9 ! nitrog5 & oxyg5 molecules ( air ! *>ges are di/ribut$ m ev5ly4 ,z a result ! track ( ea* p>ticle emitt$ 9 a radioactive decay provides _m meet+ places = ! =mation ( wat] droplets4 ,actually1 cool$ moi/ air has be5 us$ = _m decades to make ! tracks ( fa/ *>g$ p>ticles visible4 ,9 "o ( ! photographs y c see a picture ( su* 8vapor trails40 ,x is a photograph ?r\gh an app>atus call$ ! ,wilson ,cl\d ,*amb]4 ,! myriads ( radioactive dis9tegrations 9 ! debris ( a nucle> explosion c give vapor trails :i* coalesce into a real cl\d4 ,9 ?is way wea!r might be influ5c$4 7,see pictures #aa & #ab47 ,9 spite ( all ?is x rema9s highly probable t te/+ ( nucle> explosions1 z practic$ at pres5t1 does n influ5ce ! wea!r4 ,radioactivity does furni% an opportunity = droplets to =m4 ,b o!r abundant s\rces are also available = droplet =mation4 ,du/1 smoke & _m =ms ( air pollution w d ! trick4 ,foam scatt]$ f ocean waves evaporates & leaves a speck ( salt beh9d4 ,?is p>ticle ( salt may be c>ri$ by ! w9ds = _m miles & may ev5tually become ! g]m ar\nd :i* a new drop w cond5se4 ,! cosmic rays by :i* we are bomb>d$ give rise to vapor trails simil> to ^? produc$ by ! radioactive decay products4 ,among ! _m processes ( nature & ! usual by-products ( civilization ! few atomic te/s d n play an important role4 ,?is /atem5t c /&1 n z a c]ta9ty1 b z a v good guess4 ,among ! _m surprises t ! future holds "o may be closely connect$ ) ! wea!r4 ,9 ! age ( ! airplane we are gett+ m & m in=mation ab\t ! air masses ar\nd u4 ,air travel dem&s ?is in=mation & also furni%es x4 ,new te*niques1 su* z rad>1 c detect ! =mation ( a cl\d & c measure ! size ( droplets at a great di/ance4 ,9 fact ! in=mation receiv$ is s pl5tiful t "o may d\bt :e!r we c prop]ly und]/& x & utilize x4 ,=tunately we no long] ne$ to rely exclusively on our own bra9s4 ,human ?\ght is a rem>kable ?+ b x is sl[4 ,! mod]n comput+ ma*9es1 ! 8electronic bra9s10 are simpletons z comp>$ to ! app>atus :i* ea* ( u we>s 9 8 skull4 ,b ! electronic comput]s h "o advantage3 !y are fa/4 ,soon !y w be a million times z fa/ z our m5tal processes4 ,! expression 8fa/ z ?\ght0 is dat$--x is a contempor>y ( ! horse-&-buggy4 ,! electronic ma*9es c dige/ wea!r in=mation z fa/ z x is receiv$4 ,"s progress has already be5 made4 ,9 a few ye>s all wea!r pr$ictions may be ma*9e-made4 ,?is ne$ n mean t wea!r c be pr$ict$ ) c]ta9ty or = a long "t ahead4 ,! trigg] processes :i*1 />t+ f an insignificant & unnotic$ spot ( turbul5ce1 c gr[ into ! dim5sions ( a cyclone w set a limit to any art ( pr$iction4 ,b to ! ext5t t wea!r _c be pr$ict$ x may be influ5c$4 ,if small causes may h big effects !n ev5 ! puny means available to man may *ange ! wea!r--provid$ we "k h[ & :]e to apply ! lev]4 ,fir/ we %all h to acquire a bett] und]/&+ ( ! wea!r-sci5ce ( meteorology4 ,!n we %all h to look = ! appropriate trigg] me*anism4 ,?is may be a cl\d ( du/ ( ! "r k9d--or else a *emical--or p]haps a great numb] ( radioactive p>ticles4 ,9 "o way or ano!r atomic explosions may be us$ z ! trigg] b ! trigg] w n be effective until & unless ! re/ ( ! ma*9]y is und]/ood4 ,( c\rse atomic explosions _c be us$ 9 really significant numb]s unless we le>n h[ to avoid ^? radioactive by-products :i* are really dang]\s4 ,=tunately ! use ( nucle> fusion1 be/ kn[n f ! hydrog5 bomb1 makes x possible to regulate ! k9d ( radioactivity "o obta9s4 ,we may make only su* k9ds ( activity :i* decay be=e !y h a *ance to get into ! human body4 ,exp]i5ce has prov$ t to talk ab\t wea!r is n dang]\s4 ,to d some?+ ab\t ! wea!r w be m risky4 ,%all ! wea!r become a w>d ( ! gov]nm5t8 ,%all we h ,republican ,ra9/orms & ,democratic ,dr\ghts8 ,9 ?is way we %all c]ta9ly lose ! la/ safe topic ( conv]sation4 ,9 ! n>r[] conf9es ( ,europe :]e sov]eign nation is a few h\rs f sov]eign nation 7z ! w9d bl[s7 ! situation w be mu* m s]i\s4 ,b ev5 ! :ole planet may prove too small = fi]cely conflict+ int]e/s :5 m kn[+ f+]s are plac$ on m s5sitive trigg]s4 ,to gov]n ! wea!r c be mo/ useful4 ,x c\ld give ample livelihood to all ! p ( ! e>? & to _m m billions4 ,su* endeavor is surely good & x w\ld appe> peaceful4 ,b 9 ?is case z 9 _m o!r cases k w lead to p[] & p[] w lead to disa/] if x is n temp]$ by wisdom4 ,yet ?is k or "s simil>ly dang]\s k w come to u 9 our lifetimes4 ,nucle> explosions d n /& alone z a pot5tial s\rce ( mis*ief4 ,,*apt] ,,xvii ,safety ( ,nucle> ,reactors ,at ! beg9n+ ( ! sci5tific & indu/rial revolution two old ambitions 7 f\nd to be impossible dreams4 ,"o 0 ! transmutation ( elem5ts1 ! o!r ! ma*9e ( p]petual motion4 ,mod]n nucle> physici/s _h to retract "o ( ^! /atem5ts3 elem5ts c be transmut$4 ,b ! product is exp5sive1 = ! "t be+ mu* m exp5sive ?an gold4 ,! p]petual motion ma*9e rema9s impossible 9 pr9ciple b ! problem may be consid]$ solv$ 9 practice4 ,x c be prov$1 ( c\rse1 t a ma*9e c d useful "w only if x burns up "s fuel4 ,b ! price ( fuel is q (t5 less ?an ! co/ to op]ate & ma9ta9 ! ma*9e4 ,nucle> fuel ev5 today is no m exp5sive ?an conv5tional fuel 9 _m p>ts ( ! ,unit$ ,/ates4 ,nucle> fuel is nei!r heavy nor bulky & c be !re=e transport$ easily4 ,9 ^? p>ts ( ! _w :]e ord9>y fuel is exp5sive1 nucle> en]gy w soon become ( great importance4 ,fur!rmore1 we %all le>n to use mo/ ( ! en]gy 9 uranium r ?an j ! "p conta9$ 9 its r>e & valuable isotope1 ,u4 ,"o only has to add a neutron to common ,u to get radioactive ,u4 ,9 ! c\rse ( "t ?is decays into plutonium4 ,?is elem5t c be us$ l ,u3 ,x produces fission1 a great am\nt ( en]gy & en\gh neutrons to keep ! process go+4 ,we %all also le>n to extract en]gy f o!r nucle> fuels4 ,?orium acts l uranium1 :ile deut]ium c give en]gy by build+ up bigg] nuclei r ?an break+ !m into small] pieces4 ,!re=e ! s\rce ( en]gy w be univ]sally available & q inexp5sive4 ,?is really means t we are z well (f z ?\gh we _h a ma*9e ( p]petual motion4 ,b1 ( c\rse1 all ?is does n mean t ! ma*9e w d its job free ( *>ge4 ,ev5 a p]petual motion ma*9e w\ld ne$ s]vic+ & ma9t5ance4 ,un=tunately our nucle> ma*9es ne$ a lot ( su* s]vic+ & !re=e = ! "t be+1 nucle> en]gy is n ! *eape/4 ,! ma9 reason :y a nucle> en]gy s\rce1 or a nucle> reactor is difficult & exp5sive to run is t ! reactor aft] a %ort "t ( op]ation becomes /rongly radioactive4 ,!re=e x _c be approa*$ & x has to be h&l$ by remote control4 ,we c h>dly expect t en]gy w be free l air or wat]4 ,b :5 we le>n h[ to h&le inexp5sively our nucle> ma*9es1 we %all be able to obta9 en]gy = a reasonable price at any place on ! e>?4 ,soon] or lat] conv5tional fuel w become sc>ce4 ,b nucle> en]gy w all[ ! indu/rial revolution to cont9ue & to exp& into e corn] ( ! e>?4 ,!re c be little d\bt t dur+ ! next decades nucle> reactors w greatly multiply & by ! beg9n+ ( ! next c5tury !y w be f\nd ev]y:]e4 ,x is !re=e ( ! greate/ importance t ^! reactors %\ld be op]at$ safely4 ,on ! face ( x1 a nucle> reactor is a sluggi% in/rum5t :i* c be made to run itself4 ,b ! ease ( op]ation is deceptive4 7,see picture #ac47 ,"o ne$ n fe> t a nucle> reactor might explode l an atomic bomb4 ,nucle> explosives are v c>efully con/ruct$ s t !y c release a lot ( en]gy 9 a %ort "t4 ,nucle> reactors on ! o!r h& are put toge!r s z to make x possible t en]gy w be releas$ only at a mod]ate rate4 ,"s reactors if improp]ly h&l$ may explode1 b ! viol5ce ( ! explosion _c greatly exce$ t ( a simil> weight ( high explosive4 ,nev]!less a reactor accid5t c\ld become exce$+ly dang]\s4 ,! reactor is *>g$ ) radioactive fission products & "s o!r radioactive sub/ances produc$ by neutron absorption4 ,any accid5t :i* w all[ ev5 a portion ( ^! products to escape into ! air w endang] p at a consid]able di/ance 9 ! d[nw9d direction4 ,"o reason :y reactors c be dang]\s is t 9 protract$ op]ation ( ! reactor1 fission products :i* h long] lives accumulate4 ,x is precisely ^! long]-liv$ products :i* are m dang]\s because !y h a bett] *ance to f9d _! way into ! human body4 ,reactors are n[ plann$ :i* w produce #cjj1jjj kil[atts ( electricity4 ,if su* a reactor op]ates = half a ye> & !n explodes & releases its radioactive cont5t into ! atmosph]e1 its radioactivity w be comp>able to t ( a hydrog5 bomb4 ,9 "o important respect su* an accid5t w\ld be worse ?an a hydrog5 explosion4 ,! nucle> explosive lifts mo/ ( its radioactive products to a high altitude & ! poison\s activity gets disp]s$ & dilut$ be=e x desc5ds4 ,! activity f a reactor on ! o!r h& w rema9 close to ! gr\nd & might endang] ! lives ( ! p 9 an area ( hundr$s ( squ>e miles4 ,x w contam9ate an ev5 great] t]ritory4 ,9 ! ext5sive op]ation ( _m reactors 9 ! ,unit$ ,/ates no "o has yet be5 kill$ by ! radioactivity4 ,?is has be5 due to extremely c>eful op]ation & also to good luck4 ,we mu/ be prep>$ t soon] or lat] accid5ts w occur4 ,on ! o!r h& we mu/ try to take suffici5t precautions to avoid ! k9d ( cata/rophic accid5t :i* we h m5tion$ above4 ,) great c>e su* accid5ts c inde$ be avoid$4 ,9 ?9k+ ( all k9ds ( man-made ma*9es we f9d "s :i* move fa/ & seem dang]\s l1 = in/ance1 airplanes2 o!rs :i* are /ation>y & app>5tly h>mless1 l ! ba? tub4 ,yet m accid5ts happ5 9 ba? tubs ?an 9 air travel4 ,! mo/ dang]\s elem5t 9 all op]ations is ! human elem5t4 ,we ourselves con/itute ! greate/ safety haz>d4 ,?is is a situation no diff]5t 9 nucle> te*nology ?an 9 any o!r k9d ( te*nology4 ,:at is new 9 nucle> te*nology is t a reactor is usually v safe b may become extremely dang]\s :5 some?+ unexpect$ happ5s to x4 ,also we d>e n use ! me?od ( trial & error4 ,an error 9 ! reactor bus9ess c\ld exact a f> heavi] toll ( lives ?an an error 9 ! te/+ ( ,h-bombs4 ,we _c wait to le>n by exp]i5ce2 we mu/ =e/all accid5ts4 ,an especially difficult safety problem is connect$ ) ! use ( reactors 9 small c\ntries4 ,a s]i\s accid5t c\ld endang] ! lives ( p 9 adjac5t c\ntries4 ,?us mod]n te*nology may =ce coop]ation across national b\nd>ies4 ,!re is only "o way to avoid traffic accid5ts & t is c>e ex]cis$ by ev]yone1 p>ticul>ly ! driv]s4 ,simil>ly reactor safety w dep5d on ! p :o op]ate ! reactors4 ,at ! same "t a lot ( help c be obta9$ by c>eful con/ruction & scrut9y ( ea* new reactor4 ,"o ( ! fir/ acts ( ! ,atomic ,en]gy ,commission 0 to e/abli% a ,committee = ,reactor ,safegu>ds4 ,) ! pass+ ( ye>s ?is committee _h to take on m heavy responsibilities4 ,at fir/ x _h to op]ate "u secrecy4 ,) ! wid] & m public use ( reactors ! safety consid]ations are becom+ m available to ! public4 ,! "q ( safe op]ation ( a ma*9e _c be sep>at$ f a ?or\gh und]/&+ ( ! work+ ( ! ma*9e4 ,we _c attempt to give an adequate description ( a reactor or ( ! safety rules4 ,a few g5]al /atem5ts h to suffice4 ,a work+ reactor is full ( neutrons4 ,9 a small fraction ( a second ^! neutrons produce fission & a new g5]ation ( neutrons comes into be+4 ,9 sl[ reactors :i* conta9 lots ( light elem5ts l hydrog5 or c>bon1 ! neutrons move ) spe$s little great] ?an t ( s\nd & a g5]ation may la/ z long z a millisecond 7"o ?\s&? ( a second74 ,9 fa/ reactors :i* conta9 almo/ exclusively heavi] elem5ts l uranium or iron1 neutrons move ) a great spe$ :i* is ab\t ?ree p] c5t ( ! spe$ ( light4 ,9 ?is case "o g5]ation replaces ano!r 9 less ?an a microsecond 7"o million? ( a second74 ,=tunately n all ! neutrons get reproduc$ s rapidly4 ,"s fissions produce delay$ neutrons :i* are emitt$ usually ) a delay ( sev]al seconds4 ,9 a /eadily work+ reactor ea* g5]ation %\ld h ! same numb] ( neutrons z ! previ\s "o4 ,if ea* succe$+ g5]ation has ev5 a slight surplus1 ! reactor w become hot & may explode 9 a small fraction ( a second4 ,! ma9 reason :y safe op]ation is possible is ! fact t fa/ multiplication c occur only if ea* g5]ation becomes m popul\s ev5 :5 "o does n c\nt ! delay$ neutrons4 ,a slightly ov]active reactor is easily gov]n$1 b !re comes a po9t :5 ! dormant dragon beg9s to /ir4 ,?is happ5s :5 !re are en\gh neutrons produc$ s t multiplication c occur )\t wait+ = ! delay$ neutrons4 ,at t po9t a well behav$ dragon w p]=m a h>mless action4 ,= in/ance x may bl[ a fuse4 ,b a vici\s dragon w spit radioactive fire4 ,x is n easy to pr$ict :e!r ! dragon w be always well behav$4 ,b ) c>eful analysis "o c make su* a pr$iction4 ,= in/ance "o mu/ look into ! "q ( :e!r ! reactor is /able4 ,if x gets hott]1 does ?is make ! reactor proce$ ev5 fa/] s t ! rate ( heat+ increases & ! reactor runs away8 ,9 a /able reactor excess heat %\ld t5d to /op ! en]gy production & ?us ! reactor cools & returns to its normal op]at+ temp]ature4 ,b too great a /ability may also be dang]\s4 ,heat+ may be ov]comp5sat$ by ! cool+ me*anism2 aft] ! reactor has become too cold x may !n heat up too fa/ & ov]%oot aga94 ,we mu/ gu>d n only aga9/ a simple run-away1 b also aga9/ increas+ oscillations4 ,9 _m reactors unusual *emical comp\nds are us$4 ,a reactor accid5t may />t ) no?+ worse ?an an ord9>y *emical reaction betwe5 /range comp\nds "u /range conditions4 ,b if ?is *emical reaction de/roys ! reactor suffici5tly to all[ "s fission products to escape1 !n su* a *emical accid5t c be z bad z "o ( nucle> orig94 ,9 ! int]ior ( ! reactor mat]ials are expos$ to unusually /rong radiation4 ,"u ?is effect "s mat]ials c *ange _! *emical prop]ties s t :at has be5 in]t z a con/ruction mat]ial may become dang]\s dur+ ! op]ation ( ! reactor4 ,p]haps ! mo/ important s+le item is ! arrangem5t ( me*anical controls4 ,! reactor is adju/$ by a sy/em ( %eets or rods made ( a mat]ial :i* absorbs neutrons4 ,?is arrangem5t mu/ be s con/ruct$ t ! control rods c be )drawn only at a v sl[ rate4 ,b x mu/ be possible to put !m back q fa/4 ,any dang] signal %\ld %ove ! absorb]s 9 at maximum spe$4 ,! te*nical expression is 8scram40 ,! ma9 po9t1 h[ev]1 is t all ! dang]s & safety devices c be /udi$ & aft] c>eful /udy a nucle> accid5t c be avoid$4 ,"s reactors are n[ s ?or\ghly und]/ood t !y c be safely us$ = tra9+ ( future nucle> eng9e]s4 ,o!r reactors :i* are m p[]ful or less well /udi$ h to be us$ m c>efully4 ,"s reactors %\ld be1 & are be+1 enclos$ 9 gas-tight conta9]s4 ,if an explosion occurs ! fission products w be h>mlessly conf9$ inside ! conta9]4 ,( c\rse1 "o mu/ be q sure t ! reactor is ( su* a type t x _c produce an explosion great en\gh to bur/ ! conta9] & :at is ev5 m important "o %\ld be q sure t ! conta9] is clos$ except :5 ! reactor is %ut d[n & completely safe4 ,(t5 x may be be/ to build ! reactor und]gr\nd4 ,! safety ( a reactor1 ( c\rse1 dep5ds to a great ext5t on ! use to :i* ! reactor is put4 ,9 g5]al a p[] /ation is less likely to give tr\ble ?an a mov+ p[] s\rce4 ,x is n probable t nucle> locomotives w ev] be safe4 ,9 nucle> %ips m room is available & m room p]mits m safety measures4 ,b ev5 s ! safety ( nucle> motors 9 %ips w h to be consid]$ p>ticul>ly c>efully because %ips w h accid5ts 9 h>bors4 ,betwe5 ! urg5t ne$ = progress & ! absolute necessity ( safety x is difficult to keep a s5se ( balance & "o c easily make ! mi/ake ( be+ unnecess>ily cauti\s4 ,su* unnecess>y caution 0 probably ex]cis$ :5 ! ,committee on ,reactor ,safegu>ds consid]$ ! e>?quake haz>d ( ! ,brookhav5 reactor on ,long ,isl&4 ,a seismologi/1 :o is a ,jesuit ,fa!r1 0 ask$ to tell ! committee#ae ( ! possibilities & probabilities ( an e>?quake on ,long ,isl&4 ,! *airman#af ( ! committee subject$ ! exp]t to a long & detail$ que/ion+4 ,aft] half an h\r ! ,committee on ,reactor ,safegu>ds ran out ( que/ions4 ,b ! ,jesuit ,fa!r _h n giv5 any signs ( runn+ out ( answ]s4 ,! session be+ at an end ! exp]t1 look+ ! *airman ( ! committee firmly 9 ! eye & 9 a m au?oritative voice ?an he _h yet us$1 said1 8,mr4 ,*airman1 ,i c assure y on ! highe/ au?ority t !re w be no major e>?quakes on ,long ,isl& 9 ! next fifty ye>s40 ,,*apt] ,,xviii ,by-products ( ,nucle> ,reactors ,nucle> reactors g5]ate en]gy ) ! help ( nucle> fission4 ,e "t a fission occurs we are left ) radioactive by-products4 ,x is mo/ important to prev5t ! uncontroll$ escape ( ^! fission products f ! reactor4 ,=tunately ! dang]\s products c be reta9$ 9 ! reactor--if ! ma*9e has be5 con/ruct$ & op]at$ ) reasonable c>e4 ,9 ! end1 h[ev]1 ! burnt or p>tly burnt uranium *>ge w h to be remov$ f ! reactor & fre% *>ge1 fre% fuel w h to be add$4 ,:at w become ( ! fission products at ?is "t8 ,dur+ protract$ op]ation ( a reactor mo/ ( ! %ort-liv$ fission products decay4 ,^? ) long] lives accumulate4 ,! dis*>ge ( ! reactor is /rongly radioactive1 & x w rema9 radioactive = _m ye>s4 ,"o c]ta9ly mu/ n dispose ( ?is radioactive wa/e 9 a c>eless mann]4 ,!re are1 h[ev]1 _m ways 9 :i* "o c /ore su* wa/e ) reasonable safety4 ,"o c deposit ! radioactive mat]ial 9 well-built und]gr\nd tanks4 ,"o c conc5trate ! activity1 imprison x 9 concrete blocks1 & deposit x at ! bottom ( ! ocean4 ,if "o is v mu* worri$ he might ev5 put ! radioactivity 9 rockets & let x decay h>mlessly 9 out] space4 ,^! proc$ures w co/ money & w add to ! exp5se ( nucle> en]gy4 ,x w\ld be f> bett] if we c\ld f9d a way 9 :i* ! radioactive by-products c\ld be made to s]ve a useful & safe purpose4 ,"s ( ! by-products c be us$ & h be5 us$4 ,^! uses are connect$ ) "s haz>ds4 ,fur!rmore1 only a small fraction ( ! fission products h f\nd good employm5t up to ! pres5t4 ,b ! importance ( fission products is gr[+4 ,we are us+ !m 9 rese>*4 ,a radioactive isotope imitates ! behavior ( its non-active bro!r 9 all *emical reactions & 9 all ! intricate processes 9 :i* matt] *anges its =m inside a liv+ body4 ,fur!rmore a radioactive sub/ance c be detect$ ) ! greate/ ease4 ,x c be f\nd 9 a conc5tration :i* is less ?an a million? ( a safe radiation dose4 ,:at ! microscope has be5 9 ! exploration ( ! /ructure ( organisms1 ! radioactive elem5ts may become 9 ! und]/&+ ( ! *emical function+ ( liv+ matt]4 ,) bett] und]/&+ !re comes ! possibility ( us+ radioactive by-products = diagnosis4 ,z ) ! m$ical use ( ,x-rays ! possible small damage due to radiation exposure %\ld be reg>d$ z ! price = ! help we c get f e>ly & correct recognition ( diseases4 ,9 ! treatm5t ( pati5ts1 p>ticul>ly 9 ! case ( p]sons /rick5 by canc]1 radioactive de/ruction ( ! diseas$ tissue is (t5 pref]able to ! use ( ! surgeon's knife4 ,su* radioactive treatm5t is new4 ,!re is mu* room = improvem5t4 ,appropriate use ( radioactive sub/ances = ?is purpose may become a f> m p[]ful tool & mu* m widespread ?an x is at pres5t4 ,b all ^! applications w use up only a vani%+ fraction ( ! fission products4 ,moreov]1 mo/ ( ! biologically important elem5ts are n produc$ 9 ! fission ( uranium4 ,_m useful activities c be produc$ by neutron absorption 9 reactors4 ,b among ! fragm5ts ( uranium p]haps only radio-iod9e has be5 put s f> to direct physiological use4 ,indu/ry deals ) less s5sitive objects ?an liv+ tissue4 ,!re=e great] am\nts ( radioactive mat]ials c be us$ "h4 ,& inde$ radioactivity has done a great v>iety ( jobs4 ,! p5etrat+ p[] ( ,x-rays has be5 us$ to control ! ?ickness ( %eets 9 an easy & automatic mann]4 ,radioactivity has be5 incorporat$ into surfaces :i* are expos$ to me*anical we> or corrosion1 to *eck ! rate at :i* ! surface is worn away by ! appe>ance ( activity 9 ! lubricant or o!r fluids :i* h be5 9 contact ) ! surface4 ,by su* me?ods indu/ry has accumulat$ sav+s :i* are rapidly approa*+ ! billion doll> m>k4 ,^! sav+s w increase z p le>n h[ to use ! new mat]ials4 ,b 9 all ^! cases x is important to make sure t ! activity w n hurt anyone :ile x is us$ & aft] x has s]v$ its purpose4 ,possibly ! greate/ am\nt ( radioactivity w be ne$$ 9 food /]ilization & pres]vation4 ,"o may incorporate ! activities into rods :i* w safely reta9 ! mat]ials b :i* w all[ a consid]able fraction ( ! p5etrat+ gamma rays to escape4 ,to /]ilize food means to de/roy all microorganisms4 ,_m ( ^! are radiation-resi/ant & may h to be expos$ to #ej1jjj or m ro5tg5s--t is "o hundr$ times z mu* z w\ld kill a mammal4#ag ,su* massive irradiation beg9s to affect ! food/uff itself4 ,9 "s cases /]ilization by irradiation *anges ! food m ?an w\ld be ! case by boil+ x or freez+ x4 ,9 o!r cases irradiation produces less undesirable side effects ?an any o!r me?ods4 ,ano!r way to use radiation is ! pres]vation ( agricultural products4 ,?is ne$ n be done by ! difficult proc$ure ( /]ilization4 ,x is en\gh to control pe/s & to prev5t g]m9ation ( ! se$s :i* "o is try+ to pres]ve4 ,?us we ne$ "h approximately "o p] c5t ( ! radiation t w\ld be requir$ = /]ilization4 ,by s little radiation ! food is n alt]$ to a noticeable ext5t4 ,x is precisely 9 su* processes1 :]e great am\nts ( mat]ials w h to be irradiat$1 t a sub/antial fraction ( ! fission products might f9d employm5t4 ,9 all applications c>e has to be ex]cis$ le/ radioactive mat]ials %\ld inadv]t5tly be scatt]$ ar\nd4 ,:]e great am\nts are ne$$ z 9 food /]ilization & pres]vation1 caution has to be r$\bl$4 ,t tr\ble may arise has be5 illu/rat$ by an occurr5ce 9 ,h\/on1 ,texas4 ,radioactive iridium1 :i* is a beta & a gamma emitt]1 0 be+ us$ by a c]ta9 indu/rial conc]n to take ,x-ray pictures ( metal p>ts4 ,a %ipm5t ( ?is radioactive mat]ial 9 ! =m ( p[d] pellets 0 be+ op5$ by remote control :5 compress$ gas 9 ! conta9] explod$ & scatt]$ "s radioactivity ar\nd4 ,! area 0 %ield$ b "s ( ! radioactive du/ escap$ to ! re/ ( ! build+4 ,! two m5 :o 7 op]at+ ! remote control app>atus became contam9at$4 ,!y wa%$ !mselves & clean$ up ! area b did n report ! incid5t4 ,a few weeks lat] a /&>d radiation *eck %[$ t ! plant 0 /ill radioactive4 ,company (ficials became worri$ & call$ 9 exp]ts4 ,at ?is late /age ! plant 0 ?or\ghly decontam9at$4 ,! homes ( ! two m5 7 also exam9$ & 7 f\nd to be slightly radioactive4 ,! m5 & _! families 7 tempor>ily mov$ out :ile _! homes 7 be+ clean$ up4 ,:5 !y return$1 neighbors & fri5ds %unn$ !m4 ,! f\r ye> old son ( "o ( ! m5 lo/ 8 playmates4 ,p 7 afraid to ent] ! h\ses4 ,"o ( ! h\ses 0 put up = sale b no "o want$ to buy x4 ,! fact t ! h\ses _h be5 *eck$ by radiation met]s & f\nd to be clean1 & ! fact t ! half-life ( iridium is only #ge days s t any trace ( activity w\ld disappe> 9 a reasonably %ort "t1 did n dispel p's fe>s4 ,x is =tunate t no "o 0 s]i\sly hurt 9 ?is incid5t4 ,b !re is an important lesson we c le>n f x3 ,ignorance may hurt m ?an radioactivity4 ,t a h\se %\ld lose its value 9 spite ( ! fact t its radioactive contam9ation has be5 remov$1 t a little boy %\ld be %unn$ z ?\gh radioactivity 7 infecti\s l ! plague--^! are examples ( suff]+ caus$ by "o ( ! greate/ s\rces ( human mis]y3 unreason+ fe>4 ,! greate/ pot5tialities ( fission products = ! future might lie 9 /ill a diff]5t direction4 ,radioactivity c induce mutations4 ,to :at ext5t ?is is a dang] we h discuss$ 9 an e>li] *apt]4 ,9 ! h&s ( a bre$] :o tries to br+ ab\t *anges 9 animals or plants radioactivity c\ld become exce$+ly useful4 ,( c\rse x is true t mo/ mutations are h>mful4 ,x is also true t artificial mutations h be5 produc$ = _m decades4 ,b n[ x is possible to place simple & *eap tools 9 ! h&s ( _m m p4 ,!re=e ! *ances w increase to f9d among ! _m wrong mutations ! few & decisive *anges :i* lead to improvem5t4 ,d we d>e to place dang]\s mat]ials 9 s _m h&s8 ,we %\ld n d s )\t mak+ c]ta9 t only compet5t & responsible individuals w get radioactive mat]ials4 ,?is c be done4 ,druggi/s h disp5s$ poison2 doctors & biologi/s h br$ 9 _! laboratories ! multiply+ m5ace ( g]ms4 ,all ?is 0 done & is be+ done ) safety & to ! great b5efit ( all p4 ,! use ( radioactivity %\ld be ev5 m safe because ?is mat]ial is easy to detect4 ,if poisons or g]ms become lo/1 !y may be h>d to f9d4 ,radioactive mat]ials1 h[ev]1 give unmi/akable evid5ce ( _! pres5ce4 ,x is1 ( c\rse1 nev] easy to f9d a ne$le 9 a hay/ack4 ,b ! *ance to f9d x is mu* bett] if x is a radioactive ne$le4 ,radioactive by-products ne$ n rema9 :at !y seem to be today3 dirt & dang] to be dispos$ ( & hidd54 ,b 9 ! imm$iate future we %all incur "s exp5se to keep radioactivity 9 a safe place4 ,"s gase\s by-products l ! long-liv$ krypton 7half-life3 #aj4d ye>s7 might cont9ue to give rise to real difficulties & to consid]able exp5se4 ,! tr\ble is1 ( c\rse1 t a noble gas l krypton w n be b\nd to any mat]ial by /rong bonds4 ,x may be inadvisable to let long-liv$ gases escape4 ,on ! o!r h&1 _! adsorption or _! /orage at l[ temp]ature or high pressure may prove to co/ a consid]able am\nt ( money4 ,we h be5 talk+ ab\t ! problem ( h&l+ ! by-products ( nucle> p[]4 ,?is problem w n appe> 9 prop] proportion unless we also give "s ?\ght to ! by-products ( ! k9d ( p[] we are us+ at pres5t4 ,t we d n l smoke & smog is obvi\s4 ,to :at ext5t ^! residues ( incomplete burn+ c cause canc] or o!r damage we d n "k4 ,*emi/ry is m tricky ?an radiation4 ,our lack ( k ab\t ! sl[ biological effects ( *emicals is mu* great] ?an our rema9+ unc]ta9ties ab\t radiation4 ,9 addition to ! obvi\s annoyance & worry caus$ by ! products ( incomplete combu/ion !re exi/s an int]e/+ "q connect$ ) ! result ( complete combu/ion4 ,! c>bon t has be5 deposit$ ?r\gh ! geologic ages z coal & z oil is be+ us$ up gradually & conv]t$ to a colorless1 odorless1 h>mless gas--c>bon dioxide4 ,!re is always "s c>bon dioxide 9 our atmosph]e4 ,! am\nt is approximately #cjj p>ts p] million ( common air4 ,all ! c>bon t has be5 burn$ s9ce ! beg9n+ ( ! indu/rial revolution c\ld h increas$ ! c>bon dioxide 9 ! atmosph]e by t5 p] c5t to ! value ( #ccj p>ts p] million4 ,?is increase c\ld be significant4 ,c>bon dioxide acts l a blanket or a valve = "s k9ds ( radiation4 ,9 ! daytime we receive en]gy 9 ! =m ( visible light f ! sun4 ,?is =m ( radiation has no difficulty 9 p5etrat+ ! c>bon dioxide gas4 ,h[ev]1 ! incom+ radiation is balanc$ by invisible heat radiation1 :i* fl[s out f ! e>? into space day & night4 ,?is infr>$ radiation is q simil> 9 nature to light1 only our eyes are n s5sitive to x4 ,n[ ! c>bon dioxide gas acts l a b>ri]1 ?\gh only a p>tially effective b>ri]1 to ?is outgo+ heat radiation4 ,if ! c>bon dioxide cont5t ( our atmosph]e 7 to increase too greatly1 x w\ld act l ! glass 9 a gre5h\se & our climate w\ld gr[ w>m]4 ,a t5 p] c5t increase 9 ! c>bon dioxide cont5t ( ! atmosph]e %\ld h produc$ an obs]vable rise 9 temp]ature4 ,su* a temp]ature rise has n1 9 fact1 be5 obs]v$4 ,! reason is t n all ! c>bon dioxide :i* has be5 g5]at$ 9 ! processes ( combu/ion has actually rema9$ 9 ! atmosph]e4 ,mo/ ( x has f\nd its way into ! great res]voir ( our oceans4 ,"s ( x is deposit$ z lime at ! bottom ( ! oceans4 ,h[ev]1 "s "t is requir$ = ! c>bon dioxide to be remov$ f ! atmosph]e & to rea* ! oceans4 ,"o w\ld expect1 !re=e1 t !re w\ld h be5 at lea/ a slight increase 9 ! c>bon dioxide cont5t ( ! atmosph]e4 ,measurem5ts %[ t ?is is ! case & t ! increase is ab\t two p] c5t--:i* is too small to h *ang$ our climate4 ,if we cont9ue to consume fuel at an increas+ rate1 h[ev]1 x appe>s probable t ! c>bon dioxide cont5t ( ! atmosph]e w become high en\gh to raise ! av]age temp]ature ( ! e>? by a few degrees4 ,if ?is 7 to happ51 ! ice caps w\ld melt & ! g5]al level ( ! oceans w\ld rise4 ,coa/al cities l ,new ,york & ,seattle might be inundat$4 ,?us ! indu/rial revolution us+ ord9>y *emical fuel c\ld be =c$ to end be=e ! advantages ( civilization h spread all ov] ! e>?4 ,h[ev]1 x might /ill be possible to use nucle> fuel4 ,) nucle> fuel ! indu/rial revolution & its c\ntless b5efits = man c\ld cont9ue to e "p ( ! globe4 ,! by-products ( ! nucle> age are less bulky & !re=e are m easily h&l$ ?an ! by-products ( our coal- & oil-economy4 ,! ma9 advantage ( nucle> en]gy may yet turn out to be ?is3 ,) prop] c>e nucle> en]gy may turn out to be ! cleane/ among ! available s\rces ( p[]4 ,,*apt] ,,xix ,! ,nucle> ,age ,! future dep5ds on p4 ,p are unpr$ictable4 ,!re=e1 ! future is unpr$ictable4 ,h[ev]1 "s g5]al conditions ( mank9d dep5d on ?+s l ! developm5t ( te*nology1 ! control won by man ov] nature & ! limitations ( natural res\rces4 ,^! c be pr$ict$ ) a little great] confid5ce4 ,! future is unkn[n b 9 "s respects its g5]al outl9e c be guess$4 ,su* guesses are important4 ,!y influ5ce our pres5t outlook & our pres5t actions4 ,! nucle> age has n yet />t$4 ,our s\rces ( en]gy are n yet nucle> s\rces4 ,ev5 9 ! milit>y field1 :]e developm5t has be5 mo/ rapid1 ! /ructure ( ! arm$ =ces has n yet adju/$ itself to ! facts ( ! nucle> age 9 a reali/ic mann]4 ,9 politics ! atomic nucleus has ent]$ z a promise & z a m5ace--n z a fact on :i* we c build & ) :i* we c reckon4 ,"s te*nical pr$ictions seem safe3 ,nucle> en]gy w n r5d] our old] p[] plants obsolete 9 ! ne> future4 ,b nucle> en]gy w make x possible to ma9ta9 ! pace--ev5 ! accel]ation--( ! indu/rial revolution4 ,x w be possible to produce all ! en]gy we ne$ at a mod]ate co/4 ,fur!rmore--& ?is is ! important po9t--?is en]gy w be available at any place on ! globe at a co/ :i* is fairly uni=m4 ,! great] ! ne$ = p[]1 ! soon] w x be feasible to satisfy ! ne$ ) ! help ( nucle> reactors4 ,nucle> en]gy c be made available at ! mo/ outl&i% places4 ,x c be us$ on ! ,ant>ctic cont95t4 ,x c be made to "w on ! bottom ( ! ocean4 ,! exp&+ front ( indu/rialization has be5 call$ ! 8revolution ( ris+ expectations40 ,t nucle> en]gy %\ld be involv$ 9 ! curr5t & 9 ! turbul5ce ( ?is exp&+ front1 is inevitable4 ,"o c say a little m ab\t ! effects ( sci5tific & te*nological discov]ies on ! relations among ! p ( ! globe4 ,) add$ discov]ies raw mat]ials w no long] be ne$$ ) ! old urg5cy4 ,= mo/ sub/ances sub/itutes are be+ f\nd4 ,?is may make = great] economic indep5d5ce4 ,on ! o!r h&1 new possibilities w pres5t !mselves4 ,we %all le>n h[ to control ! air & h[ to cultivate ! oceans4 ,?is w call = coop]ation & m int]dep5d5ce4 ,! dang]s f radioactive by-products w act 9 a simil> direction4 ,! radioactive cl\d releas$ f a reactor accid5t may be m dang]\s ?an a nucle> explosion4 ,su* a cl\d w n /op at national b\nd>ies4 ,"s prop] =m ( int]national responsibility w h to be develop$4 ,:at effect ! exi/5ce ( nucle> weapons w h ^u ! coexi/5ce ( nations is a "q less und]/ood & less explor$ ?an any o!r affect+ our future4 ,mo/ p turn away f x ) a feel+ ( t]ror4 ,x is n easy to look at ! "q ) calm reason & ) little emotion4 ,a few pr$ictions seem di/urb+ b are highly probable3 ,nucle> secrets w n keep4 ,k ( nucle> weapons w spread among nations--at lea/ z long z indep5d5t nations exi/4 ,prohibition w n "w4 ,laws or agreem5ts :i* />t ) ! ^w 8don't0 c be brok5 & w always be brok54 ,if !re is hope1 x mu/ lie 9 ! direction ( agreem5ts :i* />t ) ! ^w 8d40 ,! idea ( 8,atoms = ,peace0 succe$$ because x result$ 9 concrete action4 ,an all-out nucle> w> betwe5 ! major p[]s c\ld occur b we may h good hope t x w n occur if we rema9 prep>$ to /rike back4 ,no "o w want to provoke ! deva/ation ( 8 own c\ntry4 ,atomic bombs may be us$ aga9/ cities4 ,b !re w be no milit>y advantage 9 de/roy+ cities4 ,9 a %ort & highly mobile w> nei!r c5t]s ( supply & communication nor massive means ( production w c\nt4 ,if cities are bomb$1 ?is w be done prim>ily = reasons ( psy*ological w>f>e4 ,we mu/ be & we are prep>$ = ?is k9d ( w> b only z a measure ( retaliation4 ,!re is good reason to believe t z long z we are prep>$ = all-out w>1 our civilian population w n suff] f a nucle> attack4 ,! c]ta9ty ( a c\nt]bl[ gives real protection aga9/ all-out w>4 ,no su* protection exi/s aga9/ w>s limit$ 9 t]ritory & 9 aims4 ,9 ! hi/ory ( mank9d su* w>s h be5 mo/ frequ5t4 ,!re is no indication t ^! limit$ w>s h end$4 ,we mu/ be prep>$ = ^! conflicts ) effective & mobile units1 & ?is requires ! use ( nucle> firep[]4 ,nucle> weapons w c]ta9ly h a pr(\nd effect ^u su* limit$ w>f>e4 ,n all ( ?is effect ne$ be & inde$ x mu/ n be 9 ! direction ( great] deva/ation4 ,9 a nucle> w> x w n make s5se to use mass$ manp[]4 ,any su* conc5tration w provide too good a t>get = atomic weapons4 ,to use big1 co/ly & conspicu\s ma*9es ( w> w be unwise4 ,su* ma*9es w be defeat$ by nucle> explosions 9 ! same way z ! mail$ knight w5t d[n be=e fire>ms4 ,any fight+ unit 9 a nucle> w> w h to be small1 mobile1 inconspicu\s & capable ( indep5d5t action4 ,su* units :e!r on sea1 l& or 9 ! air _c rely & w n rely on fix$ l9es ( supply4 ,!re w be no possibility & no ne$ to occupy t]ritory & to fight at fix$ & def9ite fronts4 ,if a w> %\ld be f\ght = milit>y reasons & = milit>y advantage1 x w consi/ ( %ort & %>p local engagem5ts involv+ skill & advanc$ te*niques & n involv+ masses t slaught] & are be+ slaught]$4 ,if an invad] adopts extreme disp]sion1 x w become impossible to defeat him ) atomic weapons4 ,b a v highly disp]s$ army c be defeat$ by a det]m9$ local population4 ,!re=e ! ma9 role ( nucle> weapons might well be to disp]se any /rik+ =ce s t ! resi/ance ( p def5d+ _! homes c become decisive4 ,nucle> weapons may well become ! answ] to mass$ armies & may put back ! p[] into ! h&s :]e we believe x belongs3 ! h&s ( ! p4 ,at ?is po9t we are br\ght back to ! ma9 topic ( ?is book3 radioactivity4 ,9 a limit$ nucle> w> ! radioactive fall\t w probably kill _m ( ! innoc5t by/&]s4 ,we h se5 t ! te/+ program gives rise to a dang] :i* is mu* small] ?an _m risks :i* we take 9 our /ride )\t any worry4 ,9 a nucle> w>1 ev5 9 a limit$ "o1 ! situation w probably be q diff]5t4 ,t noncombatants suff] 9 w>s is n new4 ,9 a nucle> w>1 ?is suff]+ may well be increas$ fur!r due to ! radioactive poisons :i* kill fri5d & foe1 soldi] & civilian alike4 ,=tunately !re exi/s a way out4 ,our e>ly nucle> explosives h us$ fission4 ,9 ! fission process a great array ( radioactive products are =m$1 "s ( !m int5sely poison\s4 ,m rec5tly we h le>n$ h[ to produce en]gy by fusion4 ,fusion produces few] & v mu* less dang]\s radioactivities4 ,actually ! neutrons :i* are a by-product ( ! fusion reaction may be absorb$ 9 almo/ any mat]ial & may aga9 produce an assortm5t ( radioactive nuclei4 ,h[ev]1 by plac+ only c]ta9 mat]ials ne> ! !rmonucle> explosion1 "o may obta9 a weapon 9 :i* ! radioactivity is h>mless4 ,?us ! possibility ( clean nucle> explosions lies be=e u4 ,clean1 flexible & easily deliv]$ weapons ( all sizes w\ld make x possible to use ^! bombs z we want to use !m3 z tools ( def5se4 ,:5 /opp+ an aggressor we w\ld n let loose great quantities ( radioactive atoms :i* w\ld spread dea? :]e we want$ to def5d fre$om4 ,clean nucle> weapons w\ld be ! same z conv5i5tly packag$ high explosives4 ,!y w\ld be no?+ m4 ,! possibility ( clean explosions op5s up ano!r developm5t3 ! use ( nucle> explosives = ! purposes ( peace4 ,conv5tional high explosives h be5 us$ 9 peace fully z mu* z 9 w>4 ,f m9+ to ! build+ ( dams !re is a great v>iety ( important jobs t dynamite has p]=m$4 ,nucle> explosives h n be5 us$ 9 a simil> way4 ,! reason is ! dang] f radioactivity4 ,once we fully ma/] ! art ( clean explosions peaceful applications w foll[ & ano!r /ep w be made 9 controll+ ! =ces ( nature4 ,all ?is is ( c\rse only a small "p 9 ! process ( ! increas+ p[] ( man & ! increas+ responsibility ( man4 ,z ! impossible ( ye/]day becomes ! accompli%$ fact ( today we h to be m & m aw>e ( our neighbors on ?is %r9k+ planet4 ,! arts ( peace may lead to conflict+ int]e/ z easily z !y may lead to fruitful coop]ation4 ,if we ev] le>n to control ! climate ( ! _w1 a nation may f9d itself 9 ! same relation to ano!r nation z two f>m]s :o h to use ! wat]s ( ! same riv]4 ,rivals are m5 :o fight ov] ! control ( a riv]4 ,:5 ! same ^w 8rivals0 comes to mean coop]ation = ! be/ common use ( ! riv] or any o!r res\rce--t w be ! "t ( law & ( peace4 ,surely ?is s\nds l ,utopia & no "o sees ! way4 ,b ! g5]al direction 9 :i* we %\ld g is n to consid] atomic explosives & radioactivity z ! inv5tions ( ! devil4 ,on ! contr>y1 we mu/ m fully explore all ! consequ5ces & possibilities t lie 9 nature1 ev5 :5 ^! possibilities seem fright5+ at fir/4 ,9 ! end ?is is ! way t[>d a bett] life4 ,x may s\nd unusually optimi/ic 9 ! atomic age1 b we believe t ! human race is t\gh & 9 ! long run ! human race is reasonable4 ,,gloss>y ,activity3 ,%ort = radioactivity4 ,also ! /r5g? ( a radioactive s\rce measur$ 9 dis9tegrations p] second4 ,air bur/3 ,a nucle> explosion at su* an altitude t ! fireball does n t\* ! e>?'s surface4 ,an air bur/ produces v little local fall\t4 ,alpha ray 7p>ticle73 ,en]getic b non-p5etrat+ radiation emitt$ by heavy radioactive nuclei4 ,an alpha p>ticle consi/s ( two neutrons & two protons1 & is id5tical ) ! nucleus ( ! ord9>y helium atom4 ,atom3 ,a positively *>g$ nucleus surr\nd$ by negatively *>g$ electrons4 ,atomic bomb3 ,a fission bomb4 ,atomic cl\d3 ,! cl\d rema9+ aft] ! en]gy ( ! explosion has be5 c>ri$ (f by ! %ock wave & ! !rmal radiation4 ,x consi/s ( cond5s$ wat] vapor1 gr\nd mat]ial1 & bomb debris includ+ ! radioactivity4 ,atomic en]gy3 ,en]gy releas$ 9 nucle> reactions1 = example 9 fission4 ,atomic en]gy & nucle> en]gy mean ! same ?+1 b ! latt] "n is m appropriate4 ,atomic reactor3 ,same z nucle> reactor4 ,backgr\nd radiation3 ,natural radiation due to cosmic rays1 & due to radioactive sub/ances 9 ! e>?1 9 ! atmosph]e1 & 9 our own bodies4 ,beta ray 7p>ticle73 ,an en]getic electron or positron emitt$ by "s radioactive nuclei4 ,practically all ( ! fission products are beta 7electron7 emitt]s4 ,bla/ wave3 ,same z %ock wave4 ,cesium3 ,a radioactive fission product4 ,x emits a #j4e million volt beta ray & a #j4g million volt gamma ray ) a half-life ( #cj ye>s4 ,! daught] nucleus is /able b>ium4 ,*a9 reaction3 ,self-ma9ta9$ sequ5ce ( fissions4 ,neutrons releas$ by ! fission ( "o nucleus are us$ to induce fission 9 ano!r nucleus4 ,*romosome3 ,a small irregul>ly %ap$ body f\nd 9 cells4 ,*romosomes c>ry ! g5es1 :i* are responsible = h]$ity4 ,clean bomb3 ,a nucle> bomb :i* produces heat & bla/1 b only a negligible am\nt ( radioactivity4 ,! en]gy ( su* a bomb is d]iv$ almo/ entirely f ! fusion process4 ,cobalt3 ,radioisotope--decays into nickel ) ! emission ( a weak beta ray4 ,! half-life = ?is decay is #e4c ye>s4 ,! nickel imm$iately ejects two gamma rays ) a total en]gy ( #b4e million electron-volts4 ,cobalt bomb3 ,a radiological bomb :i* produces a l>ge quantity ( cobalt4 ,control rod3 ,a rod ( neutron-absorb+ mat]ial us$ to control ! p[] level ( a nucle> reactor4 ,cosmic rays3 ,en]getic p>ticles f out] space4 ,!y induce nucle> reactions 9 ! e>?'s atmosph]e & ?us contribute to ! backgr\nd radiation4 ,?is cosmic radiation is m int5se at high altitudes ?an at sea level4 ,c\nt]3 ,a device :i* detects nucle> radiation4 ,critical mass3 ,! am\nt ( fissionable mat]ial requir$ to su/a9 a /eady *a9 reaction4 ,) less ?an ! critical am\nt1 ! reaction /ops because too _m neutrons are lo/4 ,cyclotron3 ,a ma*9e t accel]ates *>g$ p>ticles to high en]gy4 ,en]getic *>g$ p>ticles c be us$ to induce nucle> reactions4 ,daught]3 ,! nucleus :i* rema9s aft] decay ( a radioisotope4 ,decay3 ,spontane\s process 9 :i* a radioactive nucleus emits an alpha1 beta1 or gamma ray4 ,delay$ neutrons3 ,^? releas$ aft] a fraction ( a second to a half-m9ute or s by ! fission products4 ,!y comprise less ?an "o p] c5t ( ! total numb] ( neutrons releas$ 9 ! fission process b are useful = ! purpose ( control 9 reactors4 ,deut]ium3 ,/able hydrog5 isotope4 ,its nucleus 7call$ a deut]on7 consi/s ( "o proton & "o neutron4 ,dis9tegration3 ,same z decay4 ,dose3 ,a quantity ( radiation--usually measur$ 9 ro5tg5s4 ,e mc3 ,e9/e9's equation relat+ mass 7m7 & en]gy 7,e74 ,! spe$ ( light 7c7 ent]s z a proportionality con/ant4 ,! equation ass]ts t "o p\nd ( mass is equival5t to t5 megatons ( en]gy4 ,9 ! fission process only "o-t5? ( "o p] c5t ( ! mass is conv]t$4 ,!re=e1 to produce t5 megatons ( en]gy by fission #ajjj p\nds ( uranium w\ld be requir$4 ,electromagnetic radiation3 ,includes radio waves1 visible1 infr>$1 & ultraviolet waves2 also ,x-rays & gamma rays4 ,! latt] two are en]getic1 p5etrat+ =ms ( radiation4 ,electron3 ,a p>ticle hav+ a unit negative *>ge & a weight equal to #a_/ahdj ( ! weight ( ! lighte/ atom 7hydrog574 ,electron capture3 process 9 :i* an atomic electron unites ) a proton 9 ! nucleus produc+ a neutron & a neutr9o4 ,electron-volt3 ,! am\nt ( en]gy acquir$ by an electron :i* is accel]at$ ?r\gh an electric pot5tial ( "o volt4 ,typically1 ! en]gy requir$ to 8knock0 an electron out ( an atom is a few electron-volts or s2 p>ticles eject$ f radioactive nuclei h en]gies betwe5 a few hundr$ ?\s& & a few million electron-volts4 ,elem5t3 ,a collection ( atoms ^: nuclei all h ! same *>ge4 ,an elem5t may consi/ ( _m isotopes4 ,enri*$ mat]ial3 ,uranium :i* conta9s a great] proportion ( ! #bce-;isotope ?an is f\nd 9 ! natural ore4 ,excit$ /ate3 ,a /ate ( an atom1 molecule1 or nucleus hav+ excess en]gy4 ,z soon z possible ?is excess en]gy is releas$ & ! sy/em goes to ! gr\nd /ate4 ,fall\t3 ,radioactive p>ticles f an atomic explosion4 ,!y may be c>ri$ 9 ! atomic cl\d to l>ge di/ances f gr\nd z]o & !n 8ra9$ d[n0 to ! e>?'s surface4 ,fireball3 ,! lum9\s ball ( hot air & bomb mat]ial :i* exp&s & cools z ! %ock wave races out4 ,fission3 ,! break+-up ( a heavy nucleus into two or m fragm5ts4 ,a l>ge am\nt ( en]gy & "s free neutrons are releas$ 9 ! process4 ,fissionable mat]ial3 ,isotopes :i* und]go fission :5 bomb>d$ by sl[ neutrons3 uranium & plutonium4 ,fission products3 ,fission fragm5ts & _! daught]s1 includ+ hundr$s ( diff]5t radioactive species1 among !m /rontium & cesium4 ,fusion3 ,! comb9+ ( light nuclei into heavi] ones ) a release ( en]gy4 ,= example1 deut]on triton alpha neutron4 ,ab\t #ah million electron-volts are releas$ 9 ?is process4 ,gamma ray3 ,en]getic1 p5etrat+ electro-magnetic radiation emitt$ by c]ta9 radioactive nuclei1 frequ5tly aft] a beta emission4 ,g5es3 ,p>ts ( ! *romosomes4 ,!y are big molecules t det]m9e h]$ity4 ,gr\nd /ate3 ,! /ate ( lea/ en]gy & greate/ /ability ( atoms1 molecules1 & nuclei4 ,gr\nd z]o3 ,! po9t on ! surface ( ! e>? directly above or bel[ a nucle> explosion4 ,half-life3 ,! "t requir$ = "o half ( a l>ge numb] ( id5tical radioactive nuclei to dis9tegrate4 ,h-bomb3 ,same z hydrog5 bomb4 ,heavy hydrog53 ,same z deut]ium4 ,heavy wat]3 ,wat] ) heavy hydrog5 sub/itut$ = ord9>y hydrog54 ,hydrog5 bomb3 ,a high-yield !rmonucle> bomb4 ,iod9e3 ,a radioactive fission product ) a half-life ( #h days4 ,x emits an electron ( av]age en]gy #j4b million electron-volts & a gamma ray ( en]gy #j4d million electron-volts4 ,ion3 ,a *>g$ atom or molecule4 ,ions are produc$ 9 abundance :5 en]getic *>g$ p>ticles pass ?r\gh matt]4 ,ionization3 ,! process ( remov+ electrons f neutral atoms or molecules4 ,neutrons & gamma rays z well z en]getic *>g$ p>ticles are v effective 9 produc+ ionization4 ,iridium3 #ge day radioisotope4 ,x emits an electron ( av]age en]gy #j4b million volts & a #j4c million volt gamma ray4 ,isotopes3 ,atoms ^: nuclei h ! same numb] ( protons b a diff]5t numb] ( neutrons4 ,su* atoms h ! same *emical behavior4 ,kiloton3 ,! am\nt ( en]gy releas$ by a ?\s& tons ( ,,tnt4 ,krypton3 ,a radioactive fission product4 ,x has a t5 ye> half-life & emits an electron ( av]age en]gy #j4b million volts & a #j4e million volt gamma ray4 ,leukemia3 ,a usually fatal disease 9 :i* :ite blood cells are ov]produc$4 ,local fall\t3 ,radioactive fall\t 9 ! neighborhood ( a nucle> explosion4 ,megaton3 ,! am\nt ( en]gy releas$ by a million tons ( ,,tnt4 ,meson3 ,a p>ticle int]m$iate 9 weight betwe5 ! electron & ! proton4 ,actually1 !re are two k9ds ( mesons1 call$ pi & mu4 ,! pi meson weighs #bgf times z mu* z ! electron & is connect$ ) ! =ces t hold ! nucleus toge!r4 ,! mu meson weighs #bab times z mu* z ! electron & contributes appreciably to ! cosmic radiation4 ,microsecond3 ,"o million? ( a second4 ,x takes light #e microseconds to g a mile4 ,million volt p>ticle3 ,%ort = million electron-volt p>ticle4 ,mod]ator3 ,a mat]ial us$ 9 nucle> reactors to r$uce ! spe$ ( neutrons4 ,molecule3 ,a comb9ation ( atoms held toge!r *emically4 ,mutation3 ,a g5etic *ange1 :i* is transmitt$ to (fspr+ & affects h]$it>y *>act]i/ics4 ,su* *anges 9 g5es may be caus$ by radiation z well z *emical & !rmal ag5ts4 ,neutr9o3 ,a weightless1 un*>g$ p>ticle :i* c>ries (f en]gy 9 ! process ( beta decay4 ,neutron3 ,a neutral p>ticle1 "o ( ! basic con/itu5ts ( ! nucleus4 ,a neutron weighs slightly m ?an a proton1 & :5 free1 decays into a proton plus an electron & a neutr9o4 ,noble gases3 ,helium1 neon1 argon1 krypton1 & x5on4 ,!y d n comb9e *emically ) any elem5ts includ+ !mselves4 ,nucle> bomb3 ,a bomb :i* d]ives its en]gy f nucle> fission or fusion4 ,nucle> reactor3 ,a ma*9e = ma9ta9+ a controll$ *a9 reaction4 ,nucleus3 ,! core ( an atom1 consi/+ ( neutrons & protons4 ,its *>ge is equal to ! numb] ( protons4 ,its weight is equal to ! numb] ( protons plus ! numb] ( neutrons4 ,p]iodic sy/em3 ,! *emical elem5ts arrang$ 9 ord] ( increas+ atomic *>ge4 ,elem5ts ) simil> *emical prop]ties occur p]iodically4 ,plutonium3 ,elem5t ) *>ge #id1 produc$ by captur+ a neutron 9 uranium foll[$ by two beta emissions4 ,l uranium1 plutonium is valuable z an atomic fuel4 ,positron3 ,! positive c\nt]p>t ( ! electron4 ,potassium3 ,a natural radioactive isotope4 ,x has a half-life ( "o billion ye>s & emits beta & gamma rays4 ,proton3 ,a con/itu5t ( ! nucleus4 ,x has "o unit ( positive *>ge & weighs slightly less ?an a neutron4 ,radiation3 ,en]getic *>g$ p>ticles1 neutrons & gamma rays :i* cause ionization 9 matt]4 ,radiation is produc$ 9 nucle> explosions b also occurs naturally f cosmic rays & f ! decay ( radioactive sub/ances 9 our surr\nd+s4 ,radioactivity3 ,spontane\s nucle> decay1 releas+ an alpha1 beta1 or gamma ray4 ,radioisotope3 ,%ort = radioactive isotope4 ,radiological bomb3 ,a bomb design$ to create radioactive contam9ation4 ,radium3 ,elem5t ) *>ge #hh4 ,! pr9cipal isotope has a weight ( #bbf & emits an alpha p>ticle ) a half-life ( #afbj ye>s4 ,range3 ,di/ance travel$ by an en]getic *>g$ p>ticle 9 matt] be=e x /ops4 ,heavy *>g$ p>ticles move 9 a /raight l9e inside matt]1 b electrons frequ5tly *ange _! c\rse4 ,= ?is reason ! range ( electrons is only ab\t "o-half ! total di/ance travel$4 ,reactor3 ,same z nucle> reactor4 ,ro5tg53 ,a measure ( radiation dose--def9$ 9 t]ms ( ! am\nt ( en]gy deposit$ p] unit weight ( irradiat$ mat]ial4 ,a dose ( #djj1jjj ro5tg5s 9 liv+ tissue deposits en\gh en]gy to raise ! temp]ature by #a;,c4 ,a dose ( only #djj ro5tg5s 9 a human be+ w cause dea? fifty p] c5t ( ! "t4 ,%ock wave3 ,exp&+ front ( high pressure & /rong w9ds produc$ by an explosion4 ,spontane\s fission3 ,natural fission1 n induc$ by a neutron4 ,! half-life = ?is process 9 uranium is #h #aj ye>s4 ,/ratosph]e3 ,! atmosph]e above ! wea!r zone4 ,! altitude ( ! /ratosph]e v>ies f ?irty to fifty ?\s& feet dep5d+ on latitude & season4 ,/ratosph]ic fall\t3 ,_w-wide fall\t f big bombs ^: cl\ds rise into ! /ratosph]e4 ,on ! av]age ! radioactivity rema9s 9 ! /ratosph]e = ab\t t5 ye>s & is !n deposit$ m or less uni=mly ov] ! surface ( ! e>?4 ,/rontium3 ,a radioactive fission product4 ,x has a half-life ( #bh ye>s & emits two electrons ( av]age total en]gy #a4b million electron-volts4 ,/rontium is *emically simil> to calcium & gets deposit$ 9 bones4 ,!rmal radiation3 ,electromagnetic radiation1 ma9ly visible1 b also ultraviolet & infr>$1 emitt$ f ! fireball ( a nucle> explosion & transmitt$ long di/ances 9 ! surr\nd+ cold air4 ,!rmonucle> bomb3 ,a bomb :i* d]ives a significant fraction ( its en]gy f ! fusion ( hydrog5 isotopes4 ,!rmonucle> reaction3 ,a fusion reaction induc$ by high temp]ature4 ,?orium3 ,elem5t ) *>ge #ij4 ,! pr9cipal isotope has a weight ( #bcb & emits an alpha p>ticle ) a half-life ( #ad billion ye>s4 ,trigg] process3 ,a small cause :i* leads to a big effect4 ,tritium3 ,an isotope ( hydrog54 ,its nucleus 7call$ a triton7 consi/s ( "o proton & two neutrons4 ,tritons are radioactive beta emitt]s hav+ a half-life ( #ab4be ye>s4 ,troposph]e3 ,! wea!r portion ( ! atmosph]e1 f sea level to ab\t =ty ?\s& feet4 ,troposph]ic fall\t3 ,_w-wide fall\t1 ma9ly f small bombs 7less ?an a megaton7 ^: cl\ds rema9 9 ! troposph]e4 ,?is fall\t occurs on ! av]age two weeks to a mon? aft] ! explosion & /ays 9 a latitude close to ! latitude ( ! explosion4 ,uranium3 ,elem5t ) *>ge #ib4 ,natural uranium conta9s #a "p ( ,u to #aci p>ts ( ,u4 ,u is a fissionable mat]ial & ,u c be conv]t$ to plutonium1 :i* is fissionable4 ,x-ray3 ,p5etrat+ electromagnetic radiation1 usually made by bomb>d+ a metal t>get ) en]getic electrons4 ,x-rays & gamma rays are really ! same ?+4 ,,footnotes #a,! ^w 8noble0 is p]haps a misnom]--^! atoms d n ev5 seek ! company ( ea* o!r4 #b,quotes are put ar\nd ! ^w atom because1 hav+ lo/ "o ( its electrons1 x is no long] an ord9>y neutral atom 9 its gr\nd /ate4 #c,yet4 #d;,actually ! same /ate may be occupi$ by two neutrons & two protons4 ,! reason is t neutrons & protons are magnetic p>ticles ) a nor? & a s\? pole4 ,consequ5tly ! dem& = a diff]5ce c be satisfi$ by hav+ "o neutron 7or proton7 ) its nor? pole po9t+ up & ano!r ) its nor? pole po9t+ d[n4 #e;,x seems t neutr9os emitt$ 9 ! company ( electrons h ! symmetry ( a "r screw2 ^? emitt$ toge!r ) a positron h ! symmetry ( a left screw4 #f;,actually ! weights r>ely add up to ! orig9al #bch because1 z a rule1 "o or m neutrons are emitt$ :i* c>ry (f "s ( ! orig9al mass4 #g,only a v few unlucky ones are ov]tak5 by beta decay fir/4 #h,%e & h] husb& 7 ! discov]]s ( two elem5ts1 rh5ium & masurium4 ,"o ( ^! exi/s4 #i;,a great portion ( ! en]gy might be lo/ if ! neutron is q fa/4 ,9 ?is case ! neutron c cause int]nal excitation ( ! nucleus4 #aj,!re seems to be a good possibility t he di$ f a hepatitis entirely unrelat$ to ! initial radiation exposure4 #aa;,half-lives ( radioactive nuclei are un9flu5c$ by ! extreme temp]atures or pressures ( ! explosion1 or by ! /ate ( motion ( ! p>ticles or :]e !y happ5 to be4 #ab;,a small am\nt may drift d[n to ! gr\nd 9 ! w9ds4 ,?is may get deposit$ on leaves & grass4 #ac,! la/ l9e ( ! table is bas$ on our own e/imates4 #ad,rec5t evid5ce sugge/s ?is numb] is sometimes tw5ty-?ree4 #ae;,dubb$ by its fri5ds 8,committee = ,reactor ,prev5tion40 #af,"o ( ! au?ors4 #ag,?is diff]5ce is n surpris+4 ,:5 we /]ilize1 we h to kill all g]ms1 ev5 ^? :i* are mo/ resi/ant to radiation4 ,fur!rmore small organisms may escape ! radiation effects by m]e *ance4 ,on ! o!r h& a big & complicat$ organism w cease to function :5 ! mo/ s5sitive among its ess5tial tissues h be5 de/roy$4 ,transcrib]'s ,notes --,sil5tly correct$ a few typos4 --,reta9$ publication in=mation f ! pr9t$ edition3 ?is e,book is public-doma9 9 ! c\ntry ( publication4 --,9 ! text v]sions only1 text 9 italics is delimit$ by und]scores4