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