ENTRY            C2527   20200425                             C195C252700000001 
SUBENT        C2527001   20200425                             C195C252700100001 
BIB                 11         40                                 C252700100002 
TITLE      The New Element Berkelium (Atomic Number 97)           C252700100003 
AUTHOR     (S.G.Thompson,A.Ghiorso,G.T.Seaborg)                   C252700100004 
REFERENCE  (J,PR,80,781,1950)                                     C252700100005 
           #doi:10.1103/PhysRev.80.781                            C252700100006 
INSTITUTE  (1USABRK,1USAUCX)                                      C252700100007 
FACILITY   (CYCLO,1USABRK) The Berkeley Crocker Laboratory        C252700100008 
           60-inch cyclotron.                                     C252700100009 
INC-SOURCE The intensity of the bombardments averaged about 2     C252700100010 
           microA/cm2 and the time of bombardment was usually     C252700100011 
           about 6 hr.                                            C252700100012 
INC-SPECT  The intensity of the beam of helium ions striking the  C252700100013 
           sample was determined by measuring the charge          C252700100014 
           accumulated on the insulated target dish and foil.     C252700100015 
           The energies of the helium ions were calculated as     C252700100016 
           ranging from 30 to 35 MeV in various bombardments.     C252700100017 
SAMPLE     The Am241 used as target material for the production   C252700100018 
           of element 97 was separated from strongly neutron      C252700100019 
           irradiated plutonium into which it grew as the         C252700100020 
           daughter of the beta-particle decay of ~10-yr. Pu241.  C252700100021 
DETECTOR   (GEMUC)                                                C252700100022 
METHOD     (EXTB,CHSEP,ASPEC) The americium targets were placed   C252700100023 
           inside a special target assembly. In this assembly     C252700100024 
           the particle beam from the cyclotron was passed        C252700100025 
           through two thin duralumin foils (each 1.5 mil in      C252700100026 
           thickness) before entering the evacuated compartment   C252700100027 
           containing the sample, and the compartment was         C252700100028 
           isolated from the surroundings. The chemical           C252700100029 
           separations were made using a combination of           C252700100030 
           precipitation methods and high temperature ion         C252700100031 
           exchange columns with Dowex-50 resin. The growth of a  C252700100032 
           curium isotope decaying by the emission of alpha-      C252700100033 
           particles of energy 5.89 MeV (15%) and 5.79 MeV (85%)  C252700100034 
           was observed in a radiochemically pure berkelium       C252700100035 
           fraction. The thin deposits of the radiochemically     C252700100036 
           pure element 97 fractions on platinum plates were      C252700100037 
           examined in the differential alpha-particle pulse      C252700100038 
           analyzer. The L x-rays as counted in the xenon-filled  C252700100039 
           Geiger counter were used as the basis for calculation  C252700100040 
           of disintegration rates and total numbers of atoms.    C252700100041 
HISTORY    (20200425C) BP                                         C252700100042 
ENDBIB              40          0                                 C252700100043 
NOCOMMON             0          0                                 C252700100044 
ENDSUBENT           43          0                                 C252700199999 
SUBENT        C2527002   20200425                             C195C252700200001 
BIB                  3          3                                 C252700200002 
REACTION   (95-AM-241(A,2N)97-BK-243,,SIG)                        C252700200003 
DECAY-DATA (97-BK-243,4.6HR,EC) Measured by authors.              C252700200004 
STATUS     (TABLE) page 789.                                      C252700200005 
ENDBIB               3          0                                 C252700200006 
NOCOMMON             0          0                                 C252700200007 
DATA                 3          1                                 C252700200008 
EN-MIN     EN-MAX     DATA-APRX                                   C252700200009 
MEV        MEV        MB                                          C252700200010 
       30.0       35.0       10.0                                 C252700200011 
ENDDATA              3          0                                 C252700200012 
ENDSUBENT           11          0                                 C252700299999 
ENDENTRY             2          0                                 C252799999999