ENTRY            C2527   20200425                             C195C2527  0    1 
SUBENT        C2527001   20200425                             C195C2527  1    1 
BIB                 11         40                                 C2527  1    2 
TITLE      The New Element Berkelium (Atomic Number 97)           C2527  1    3 
AUTHOR     (S.G.Thompson,A.Ghiorso,G.T.Seaborg)                   C2527  1    4 
REFERENCE  (J,PR,80,781,1950)                                     C2527  1    5 
           #doi:10.1103/PhysRev.80.781                            C2527  1    6 
INSTITUTE  (1USABRK,1USAUCX)                                      C2527  1    7 
FACILITY   (CYCLO,1USABRK) The Berkeley Crocker Laboratory        C2527  1    8 
           60-inch cyclotron.                                     C2527  1    9 
INC-SOURCE The intensity of the bombardments averaged about 2     C2527  1   10 
           microA/cm2 and the time of bombardment was usually     C2527  1   11 
           about 6 hr.                                            C2527  1   12 
INC-SPECT  The intensity of the beam of helium ions striking the  C2527  1   13 
           sample was determined by measuring the charge          C2527  1   14 
           accumulated on the insulated target dish and foil.     C2527  1   15 
           The energies of the helium ions were calculated as     C2527  1   16 
           ranging from 30 to 35 MeV in various bombardments.     C2527  1   17 
SAMPLE     The Am241 used as target material for the production   C2527  1   18 
           of element 97 was separated from strongly neutron      C2527  1   19 
           irradiated plutonium into which it grew as the         C2527  1   20 
           daughter of the beta-particle decay of ~10-yr. Pu241.  C2527  1   21 
DETECTOR   (GEMUC)                                                C2527  1   22 
METHOD     (EXTB,CHSEP,ASPEC) The americium targets were placed   C2527  1   23 
           inside a special target assembly. In this assembly     C2527  1   24 
           the particle beam from the cyclotron was passed        C2527  1   25 
           through two thin duralumin foils (each 1.5 mil in      C2527  1   26 
           thickness) before entering the evacuated compartment   C2527  1   27 
           containing the sample, and the compartment was         C2527  1   28 
           isolated from the surroundings. The chemical           C2527  1   29 
           separations were made using a combination of           C2527  1   30 
           precipitation methods and high temperature ion         C2527  1   31 
           exchange columns with Dowex-50 resin. The growth of a  C2527  1   32 
           curium isotope decaying by the emission of alpha-      C2527  1   33 
           particles of energy 5.89 MeV (15%) and 5.79 MeV (85%)  C2527  1   34 
           was observed in a radiochemically pure berkelium       C2527  1   35 
           fraction. The thin deposits of the radiochemically     C2527  1   36 
           pure element 97 fractions on platinum plates were      C2527  1   37 
           examined in the differential alpha-particle pulse      C2527  1   38 
           analyzer. The L x-rays as counted in the xenon-filled  C2527  1   39 
           Geiger counter were used as the basis for calculation  C2527  1   40 
           of disintegration rates and total numbers of atoms.    C2527  1   41 
HISTORY    (20200425C) BP                                         C2527  1   42 
ENDBIB              40          0                                 C2527  1   43 
NOCOMMON             0          0                                 C2527  1   44 
ENDSUBENT           43          0                                 C2527  199999 
SUBENT        C2527002   20200425                             C195C2527  2    1 
BIB                  3          3                                 C2527  2    2 
REACTION   (95-AM-241(A,2N)97-BK-243,,SIG)                        C2527  2    3 
DECAY-DATA (97-BK-243,4.6HR,EC) Measured by authors.              C2527  2    4 
STATUS     (TABLE) page 789.                                      C2527  2    5 
ENDBIB               3          0                                 C2527  2    6 
NOCOMMON             0          0                                 C2527  2    7 
DATA                 3          1                                 C2527  2    8 
EN-MIN     EN-MAX     DATA-APRX                                   C2527  2    9 
MEV        MEV        MB                                          C2527  2   10 
       30.0       35.0       10.0                                 C2527  2   11 
ENDDATA              3          0                                 C2527  2   12 
ENDSUBENT           11          0                                 C2527  299999 
ENDENTRY             2          0                                 C252799999999