ENTRY C2319 20180613 C177C231900000001
SUBENT C2319001 20180613 C177C231900100001
BIB 13 42 C231900100002
TITLE New Isotopes of Einsteinium C231900100003
AUTHOR (B.G.Harvey,A.Chetham-Strode Jr,A.Ghiorso, C231900100004
G.R.Choppin, S.G.Thompson) C231900100005
REFERENCE (J,PR,104,1315,1956) C231900100006
#doi:10.1103/PhysRev.104.1315 C231900100007
INSTITUTE (1USABRK,1USAUCX) C231900100008
FACILITY (CYCLO,1USABRK) The Crocker Laboratory 60-inch C231900100009
cyclotron. C231900100010
SAMPLE The amount of Bk249 available was only 1.2x10**-8 g, C231900100011
or about 3x10**13 atoms. The target material was C231900100012
deposited as a very thin layer over a rectangular C231900100013
area 0.6x6 mm on a 0.005-cm-thick gold foil. (This C231900100014
small target area was chosen to match the area of the C231900100015
most intense helium-ion beam.) C231900100016
DETECTOR (PROPC) A windowless proportional counter was assumed C231900100017
to give a counting efficiency of 90% for the C231900100018
beta-particles from Bk249 mounted on thick platinum C231900100019
plates. C231900100020
METHOD (REC,CHSEP,ACTIV) The beam passed first through the C231900100021
gold foil and then through the Bk249 target, so that C231900100022
nuclear reaction products were ejected from the C231900100023
target in the forward direction. They were caught on C231900100024
a 0.00025-cm thick gold "catcher" foil placed about C231900100025
5.5 mm from the target foil. By this method it was C231900100026
possible to bombard the Bk249 target a large number C231900100027
of times without the necessity of dissolving it. Some C231900100028
45 bombardments, many of them for as long as 9 hours, C231900100029
were made with no loss of target material. The Bk249 C231900100030
target also contained a known amount of Cm244 from C231900100031
which Cf246 was produced by the (alpha,2n) reaction. C231900100032
MONITOR (96-CM-244(A,2N)98-CF-246,,SIG) C231900100033
MONIT-REF (,A.Chetham-Strode,P,UCRL-(3322),1956) C231900100034
ERR-ANALYS (DATA-ERR) The accuracy of the cross-section C231900100035
measurements was limited to about 30% by (1) C231900100036
uncertainty in the amount of Bk249 in the target (the C231900100037
very soft beta- activity of Bk249 is not easy to C231900100038
count accurately, since the counting yield is very C231900100039
sensitive to the thickness of the sample), and (2) C231900100040
counting statistics in those experiments in which C231900100041
yields were measured by alpha-pulse analysis. C231900100042
DECAY-DATA (97-BK-249,280.0D,B-) C231900100043
HISTORY (20180613C) BP C231900100044
ENDBIB 42 0 C231900100045
COMMON 1 3 C231900100046
DATA-ERR C231900100047
PER-CENT C231900100048
30.0 C231900100049
ENDCOMMON 3 0 C231900100050
ENDSUBENT 49 0 C231900199999
SUBENT C2319002 20180613 C177C231900200001
BIB 4 8 C231900200002
REACTION (97-BK-249(A,N)99-ES-252,,SIG) C231900200003
DECAY-DATA (99-ES-252,140.0D,A,6640.0) C231900200004
COMMENT Compiler's comment: The half-life given for Es-252 is C231900200005
a factor 3 different from recent value. Authors C231900200006
mention that their value is only approximate and C231900200007
based only on alpha-pulse analysis, not taking into C231900200008
account the (at their time uncertain) decay by EC. C231900200009
STATUS (CURVE) Fig. 6, page 1318. C231900200010
ENDBIB 8 0 C231900200011
NOCOMMON 0 0 C231900200012
DATA 2 10 C231900200013
EN DATA C231900200014
MEV MB C231900200015
23.932 1.426E-01 C231900200016
26.606 5.720E-01 C231900200017
26.963 7.583E-01 C231900200018
28.270 7.906E-01 C231900200019
29.905 1.037E+00 C231900200020
30.767 9.442E-01 C231900200021
34.957 9.641E-01 C231900200022
35.908 5.660E-01 C231900200023
39.831 3.575E-01 C231900200024
40.247 3.969E-01 C231900200025
ENDDATA 12 0 C231900200026
ENDSUBENT 25 0 C231900299999
SUBENT C2319003 20180613 C177C231900300001
BIB 3 3 C231900300002
REACTION (97-BK-249(A,2N)99-ES-251,,SIG) C231900300003
DECAY-DATA (99-ES-251,1.5D,A,6480.0) C231900300004
STATUS (CURVE) Fig. 6, page 1318. C231900300005
ENDBIB 3 0 C231900300006
NOCOMMON 0 0 C231900300007
DATA 2 16 C231900300008
EN DATA C231900300009
MEV MB C231900300010
24.051 4.116E+00 C231900300011
26.517 1.312E+01 C231900300012
26.874 1.758E+01 C231900300013
28.211 2.258E+01 C231900300014
28.716 1.951E+01 C231900300015
29.935 1.776E+01 C231900300016
30.678 1.219E+01 C231900300017
31.747 1.285E+01 C231900300018
34.897 1.021E+01 C231900300019
35.938 1.087E+01 C231900300020
35.938 8.031E+00 C231900300021
36.740 7.865E+00 C231900300022
37.899 8.822E+00 C231900300023
39.920 8.373E+00 C231900300024
39.949 9.896E+00 C231900300025
40.187 7.622E+00 C231900300026
ENDDATA 18 0 C231900300027
ENDSUBENT 26 0 C231900399999
SUBENT C2319004 20180613 C177C231900400001
BIB 4 9 C231900400002
REACTION (97-BK-249(A,3N)99-ES-250,,SIG) C231900400003
COMMENT Compiler's comment: Authors suggest that Es250 also C231900400004
can be produced due to decay of Bk249 to Cf249, C231900400005
T1/2=280 days, modern values 330 days. Multiple C231900400006
reactions/decays on Cf249 could lead to Es250; C231900400007
however, half-life value of Bk249 makes these C231900400008
contributions small. C231900400009
DECAY-DATA (99-ES-250,8.HR,EC) C231900400010
STATUS (CURVE) Fig. 6, page 1318. C231900400011
ENDBIB 9 0 C231900400012
NOCOMMON 0 0 C231900400013
DATA 2 4 C231900400014
EN DATA C231900400015
MEV MB C231900400016
28.746 1.608E+00 C231900400017
31.718 2.826E+00 C231900400018
36.740 3.907E+00 C231900400019
39.860 5.457E+00 C231900400020
ENDDATA 6 0 C231900400021
ENDSUBENT 20 0 C231900499999
SUBENT C2319005 20180613 C177C231900500001
BIB 4 9 C231900500002
REACTION (97-BK-249(A,4N)99-ES-249,,SIG) C231900500003
COMMENT Compiler's comment: Authors suggest that Es250 also C231900500004
can be produced due to decay of Bk249 to Cf249, C231900500005
T1/2=280 days, modern values 330 days. Multiple C231900500006
reactions/decays on Cf249 could lead to Es250; C231900500007
however, half-life value of Bk249 makes these C231900500008
contributions small. C231900500009
DECAY-DATA (99-ES-249,2.0HR,A,6760.0) C231900500010
STATUS (CURVE) Fig. 6, page 1318. C231900500011
ENDBIB 9 0 C231900500012
NOCOMMON 0 0 C231900500013
DATA 2 6 C231900500014
EN DATA C231900500015
MEV MB C231900500016
34.273 8.776E-01 C231900500017
35.878 1.823E+00 C231900500018
36.710 2.683E+00 C231900500019
38.523 5.995E+00 C231900500020
39.831 3.411E+00 C231900500021
39.979 4.429E+00 C231900500022
ENDDATA 8 0 C231900500023
ENDSUBENT 22 0 C231900599999
ENDENTRY 5 0 C231999999999