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