ENTRY 10300 20191205 14631030000000001
SUBENT 10300001 20191205 14631030000100001
BIB 11 52 1030000100002
TITLE Prompt neutrons emitted from the spontaneous fission 1030000100003
of 257Fm 1030000100004
AUTHOR (J.P.Balagna,J.A.Farrell,G.P.Ford,A.Hemmendinger, 1030000100005
D.C.Hoffman,L.R.Veeser,J.B.Wilhelmy) 1030000100006
REFERENCE (C,73ROCH,2,191,1973) Main reference. 1030000100007
(J,ANS,16,315,1973) 1030000100008
INSTITUTE (1USALAS) 1030000100009
DETECTOR (SOLST,STANK) Solid state fission fragment detector. 1030000100010
Liquid scintillation tank neutron detector. 1030000100011
SAMPLE The 257Fm was produced by successive neutron capture 1030000100012
in Cm targets irradiated in the high-flux isotope 1030000100013
reactor (HFIR) and processed at the trans uranium 1030000100014
processing facility (TRU) at Oak Ridge National 1030000100015
Laboratory. The 257Fm was further purified at Los 1030000100016
Alamos by standard cation column procedures involving 1030000100017
elution with ethanol-HCl and hot 1030000100018
a-hydroxy-isobutyrate to separate the Fm from other 1030000100019
actinides. The principle contaminant before 1030000100020
separation was ~10**6 dis/min of 253Es. A solution of 1030000100021
the purified source was evaporated on a 5*10**-3-in. Pt1030000100022
disk. 1030000100023
METHOD (COINC) 257Fm source was positioned ~3 mm from a 1- 1030000100024
cm-diam. by 30-microm-deep Si surface-barrier 1030000100025
detector. A 252Cf source, prepared in a similar 1030000100026
manner, was placed in the same position relative to a 1030000100027
second surface barrier fission detector. The two 1030000100028
sources, back-to-back, and their detectors were 1030000100029
placed in a vacuum container in the center of a 1030000100030
75-cm-diam. spherical Gd-loaded liquid scintillator 1030000100031
tank having a l5-cm-diam. cylindrical hole through 1030000100032
the center. The apparatus was placed in a low 1030000100033
background room having thick concrete walls. 1030000100034
Experimental data were collected for more than five 1030000100035
months. During that time 10532 257Fm and 98659 252Cf 1030000100036
fission events were detected. The 257Fm fission 1030000100037
detection rate varied from 5.5 SF/h at the start of 1030000100038
the experiment to 1.8 SF/h at the conclusion. From a 1030000100039
least squares fit to the observed decay rate we 1030000100040
obtained a value of 99.3 -+ 1.6 d for the half-life 1030000100041
of 257Fm, in good agreement with the recently 1030000100042
published value of 100.5 +- 0.2 d. 1030000100043
ERR-ANALYS (DATA-ERR) No information on sources of uncertainties. 1030000100044
STATUS (APRVD) Approved by author. 1030000100045
DECAY-DATA (100-FM-257,99.3D,SF) 1030000100046
HISTORY (19740529C) 1030000100047
(19760204A) Data updated, reaction corrected 1030000100048
(19830118A) Converted to reaction formalism 1030000100049
(20011227A) Updated to new date formats, lower case. 1030000100050
Units updated. 1030000100051
(20191205A) BP: Added sample information, Cf, decay, 1030000100052
the observed neutron probability distributions and 1030000100053
MISC data. 1030000100054
ENDBIB 52 0 1030000100055
NOCOMMON 0 0 1030000100056
ENDSUBENT 55 0 1030000199999
SUBENT 10300002 20191205 14631030000200001
BIB 5 6 1030000200002
REACTION (100-FM-257(0,F),PR,NU) 1030000200003
MONITOR (98-CF-252(0,F),,NU) 1030000200004
MISC-COL (MISC) Squared standard deviation of nu. 1030000200005
STATUS (TABLE) Table II, page 194 of Physics+Chemistry of 1030000200006
Fission Symp., Rochester 1973,vol.2,p.191. 1030000200007
HISTORY (20191205A) BP: Added MISC data and status. 1030000200008
ENDBIB 6 0 1030000200009
NOCOMMON 0 0 1030000200010
DATA 5 1 1030000200011
DATA DATA-ERR MONIT MONIT-ERR MISC 1030000200012
PRT/FIS PRT/FIS PRT/FIS PRT/FIS PRT/FIS 1030000200013
3.77 0.02 3.735 0.014 2.49 1030000200014
ENDDATA 3 0 1030000200015
ENDSUBENT 14 0 1030000299999
SUBENT 10300003 20191205 14631030000300001
BIB 4 5 1030000300002
REACTION (98-CF-252(0,F),PR,NU) 1030000300003
MISC-COL (MISC) Squared standard deviation of nu. 1030000300004
STATUS (TABLE) Tables I-II, page 194 of Physics+Chemistry of 1030000300005
Fission Symp., Rochester 1973,vol.2,p.191. 1030000300006
HISTORY (20191205C) BP 1030000300007
ENDBIB 5 0 1030000300008
NOCOMMON 0 0 1030000300009
DATA 3 1 1030000300010
DATA DATA-ERR MISC 1030000300011
PRT/FIS PRT/FIS PRT/FIS 1030000300012
3.735 0.014 1.57 1030000300013
ENDDATA 3 0 1030000300014
ENDSUBENT 13 0 1030000399999
SUBENT 10300004 20200113 14631030000400001
BIB 3 4 1030000400002
REACTION (100-FM-257(0,F),PR/NUM,NU) 1030000400003
STATUS (TABLE) Tables I, page 194 of Physics+Chemistry of 1030000400004
Fission Symp., Rochester 1973,vol.2,p.191. 1030000400005
HISTORY (20191205C) BP 1030000400006
ENDBIB 4 0 1030000400007
NOCOMMON 0 0 1030000400008
DATA 3 10 1030000400009
PART-OUT DATA DATA-ERR 1030000400010
NO-DIM NO-DIM NO-DIM 1030000400011
0.0 0.070 0.003 1030000400012
1.0 0.176 0.004 1030000400013
2.0 0.260 0.005 1030000400014
3.0 0.261 0.005 1030000400015
4.0 0.154 0.004 1030000400016
5.0 0.061 0.003 1030000400017
6.0 0.015 0.002 1030000400018
7.0 0.003 0.001 1030000400019
8.0 0.0001 0.0002 1030000400020
9.0 0.0001 0.0001 1030000400021
ENDDATA 12 0 1030000400022
ENDSUBENT 21 0 1030000499999
SUBENT 10300005 20200113 14631030000500001
BIB 3 4 1030000500002
REACTION (98-CF-252(0,F),PR/NUM,NU) 1030000500003
STATUS (TABLE) Tables I, page 194 of Physics+Chemistry of 1030000500004
Fission Symp., Rochester 1973,vol.2,p.191. 1030000500005
HISTORY (20191205C) BP 1030000500006
ENDBIB 4 0 1030000500007
NOCOMMON 0 0 1030000500008
DATA 3 10 1030000500009
PART-OUT DATA DATA-ERR 1030000500010
NO-DIM NO-DIM NO-DIM 1030000500011
0.0 0.041 0.001 1030000500012
1.0 0.175 0.001 1030000500013
2.0 0.308 0.002 1030000500014
3.0 0.276 0.002 1030000500015
4.0 0.146 0.001 1030000500016
5.0 0.045 0.001 1030000500017
6.0 0.008 0.0004 1030000500018
7.0 0.001 0.0002 1030000500019
8.0 0.0001 0.00006 1030000500020
9.0 0.00001 0.00001 1030000500021
ENDDATA 12 0 1030000500022
ENDSUBENT 21 0 1030000599999
ENDENTRY 5 0 1030099999999