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