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