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ASTOuNDING  SC_ENCE-FICT ION
                                                                   I
                                                                                                                                          TRA NS. I UTATJON,  J  39                          75
                        ing  it  again  and  immediately  putting  it   collision  is  exactly  head-on,  which  is
                        near  the  counter.  which  hroke  out  into   a  rare occurrence in nucleur  phenomena,                                           xw +i.
                        a  terrific  clatter  of  activity  from  all  the   too.  And  you  can't  put  '·english"  on  a   (4)   z  xw   +   H2   1.  H1.   +   2
                        electrons  emitted  by  n uclei  undergoing   neutron.   Thus  within  the  bucket  of                    l.                        l              yW+i.     +      e
                        this  last  r eaction.  No  really  conclusive   water or paraffin the neutrons are slowed                                                  ....  Z+ ::i.        - 1.
                        proof  that  t he  elen1ent  was  cadmium,   down,  and  their  probability  of  capture         •
                        but  there's  ha1-d ly  t ime for  that  in a  lec-  by  a  silver  nucleus  is  correspondingly                      Pr oton·  Bombardment
                        t ure.   And  a nyway,  we  have  already   increased,  just  as  it  is  easier-for  me,
                                                                                                                         'W
                        done  t hat  experimen t,  ,and  know  that   at least- to  catch  a  slow grounder  than   {5)  X    +   I   H1     =   hv  +    Z+l.  yW+1
                        it's  cadmium,  a nd  the  freshmen  were   a  hot line  drive.                                z          l.                                        XW+1.           +
                     •  w illing  to  t rust  us.                                                                                                           I                        "T  ,. e
                                                                                                                                                                     ►  Z,
                          I  called  the  bucket  of  water  m  my    So F AR  we  have discussed  some  three
                        recipe  a  " philosophe r's  stone" ;  it  was   possible transmutation  reactions; the ex-                          Neutron  Bombardme nt
                        d iscovered  in  O ctober,  1-934,  by  F ermi.   ample  of  the  second  happened  to  pro-                                             W- 3
                        U p  to  that  t ime  the  neut ron  sou rce  and   duce  an  isotope  of  the  original  element   ( 6)  xw   +   n1.   -  2  He*  +   z-2  V
                        silver  had  merely  been  brought  close   as  the  end  product,  but  the  same  reac-      :t         0                          I              w        +      e
                                                                                                                                                                             W- 3
                                                                                                                                                                       z - 1
                        together;  F ermi  obser ved  that  a  tre-  tion  holds  good  fo r  other  elements                                                       ~                    -~
                        mendous  increase  in  the  activation.  of   where  the  next  higher  isotope-the  un-   (7) ·  xw  ..                                WW
                        silver took  p lace when  the neutron source   stable  one  in  the  carbon-bornbarded-                    n1        :::   l.  H-i   +   z -1.               ..
                        a nd  silver  w ere  surrnunded  by  quanti-  with-deutons  case-is  actually  stable,          ~         0                           I       ►- zX  w              e
                        ~ies  of  water  or  paraffi n.   This  effect   and  this  reaction  also  leads  to  the  pro-                                                                 - 1
                        1s  broug h t  a bout  simply  by  the  slowing   d uction  of  a  new  element.  There  are                             h'V      +   XW+1
                        of the  neutr ons  from  collisions  with  the   in all some eight general reactions whiah   ( 8)  xw   +   0  nl                    z
                        h7 drogen  nuclei  of the  water  or paraffin,   have  been  fairly  well  investigated  th~t   z                                       I             W+1.    +     e
                        either  wax  or  oil.                       lead  to  the  production  of  radioactive                                                       9"- 2 +1.y          -1
                        .  As  a ny  billiard  player  k nows,  on  the   products  and  different  elements,  and  it
                        impa~t  of  two  equally  heavy  balls  the   w?uld  be  verbose  to discuss  each  in  de-               are  startina  with  the   reaction.  But  this  particular  i~otopc  j-
                        ~ r st  1s  slowed  d own,  imparting  some  of   tad.  Instead,  we  may  summarize  them   In all  cases  ,~e  . aht  be no~ed  that in   unstablc,  too,  and  it  would  also  dee.: •_m -
                        its  momen tum  to  the  second  unless -the   all  by  giving  the  reactions · in  implicit   element X , and it   1111 "'   lJ)  ,v,.th  a   pb ·e, probably  to  giYe  us  ;; 0 ~ 11  11 1 ,  ,vh1ch
                                                                    n otation, as  follows:                        some of the process  e  ::,  • we enc  1 t   •
                                                                                                                                                  1
                                                                                                                       .      f  the  same  element,  ot 1e1   is  a  stable,  known  isotope.
                                                                                                                   new isotope  o     A  d  .  .   c·l-e"'   H ow  _much  do  w e  make  by  tlic:;e
                                                                                                                                           ] ]1  a
                                                                                                                   •
                                                                                                                   tunes a! new element.   ]1   11  C::,  ~
                                                                                                                                    t .  ue  fu rther  than   methods ?  Very  little.  .'\s  yet.  1w  o ne
                                                  Alpha  Pa~tic le  Bomba~d~ent                                    the  process  may. con_  m   . .   .   has  produced  wcighable  q~1a1~tities  o_i  a
                                                                                                                            t  o  i·eacuons  it  by  chance
                                                                                                                       .
                        { 1)                                                                                       I  t 1e  given  w   '                transmuted  element,  but  1t  1s  p os:.-1ble
                                        +    He 4      - ·  n1                                                     the  final  Jroduct  happens  to  be  an  un-
                                                                                                                        .  tl  e  If  011  the other  hand  the
                                           2              0      +    z+:a  zW+3                                   sta  i I J e 1s0 op  •   .   .  • _   that  prnduction  oi  1·a<lioact i,·e  St)dium
                                                                               .
                                                                                                                                                        from  magnesium  with  the  cyclat ron  at
                                                                        L               zw+3          +            fi rst  pro( uc  ·t  foi·ined  is  a  stable  1::.otope,   Berkeley  will  make  enough  t o  m ake  it
                                                                                                                          I
                                                                                                                                             ·  1~1
                                                                                                                          .
                                                                                                                                                  ius,
                                                                                                                               a  stop  at  once.
                                                                                                                    .
                                                                        ----i►-. Z+1            +  1.  8           the  react~on  1~1  y .  1  (8)  to  cadmium,   possible  to  actually  measu re  by  physical
                        (2)                                r-i1 .                                                 on  applymg  i eact101 .   .  106  108   means  the  amount  of  neon  procluc.:cd  on
                                        +                        +                                                   .      1   t  ble  isotopes   ,   ,
                                                                                                                                                                                          ·
                                                          1                                                        which  has  tie  s a  1 i4  115  and  116   its  disintegration.  O ur little  lectu1e  ex-
                                                                                                                   110 ,  l ll,   112 1  3  'Jarti~ular  aton~   periment  required  about  $.1.._50  wor th  ·t
                                                                                                                              •  !  '
                                                                                                                  if  the  neutron  hill  any  I  ·   d   radon,  and  in  the  two  tv-,enty-second
                                                                                                                  except the first two or the_ ast on:-an
                                                                                                                                         l
                                                                                                                                                        exposures  to  the  neutron  source  ,vc
                                                                                                                  all  three of these are rar~ m  natm e~~he
                                                        Deuton  Bombardment                                       process  stops a  t  O nce  with  the  e1111::,::,ion   made  about  6.000,000  cadmium  atom s.
                                                                                                                                                 .
                                                                                                                   •  d..  .   1·11dicated in the equation.   T hat  is  0.00000000000000112  g rnms  o f
                       (.J)                                                                                        I o  ra  1at1011  as            •   cadmium-not  much  for  $150 !
                                                                                                                                                  1
                                                             n1.  +                                               H,  on  the  other  hand,  the  neutron  . ~,t~
                                                           0                                                      say the 116 isotope, the  unS t able  117  J::,O   T hese  low  yields  a re  simply  a  m atter
                                                                                                                                                        of  geometry  and  marl~s111a1}ship;  thus
                                                                                                                  tope would  be produced, decon~pose, and
                                                                                                                                   111  accordina  to the   if  a  proton  or  deuton  1s  bemg  u sed  to
                                                                                                                  we  would  have  1!l  I  n  ,   "'
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