ENTRY 10300 20191205 146310300 0 1 SUBENT 10300001 20191205 146310300 1 1 BIB 11 52 10300 1 2 TITLE Prompt neutrons emitted from the spontaneous fission 10300 1 3 of 257Fm 10300 1 4 AUTHOR (J.P.Balagna,J.A.Farrell,G.P.Ford,A.Hemmendinger, 10300 1 5 D.C.Hoffman,L.R.Veeser,J.B.Wilhelmy) 10300 1 6 REFERENCE (C,73ROCH,2,191,1973) Main reference. 10300 1 7 (J,ANS,16,315,1973) 10300 1 8 INSTITUTE (1USALAS) 10300 1 9 DETECTOR (SOLST,STANK) Solid state fission fragment detector. 10300 1 10 Liquid scintillation tank neutron detector. 10300 1 11 SAMPLE The 257Fm was produced by successive neutron capture 10300 1 12 in Cm targets irradiated in the high-flux isotope 10300 1 13 reactor (HFIR) and processed at the trans uranium 10300 1 14 processing facility (TRU) at Oak Ridge National 10300 1 15 Laboratory. The 257Fm was further purified at Los 10300 1 16 Alamos by standard cation column procedures involving 10300 1 17 elution with ethanol-HCl and hot 10300 1 18 a-hydroxy-isobutyrate to separate the Fm from other 10300 1 19 actinides. The principle contaminant before 10300 1 20 separation was ~10**6 dis/min of 253Es. A solution of 10300 1 21 the purified source was evaporated on a 5*10**-3-in. Pt10300 1 22 disk. 10300 1 23 METHOD (COINC) 257Fm source was positioned ~3 mm from a 1- 10300 1 24 cm-diam. by 30-microm-deep Si surface-barrier 10300 1 25 detector. A 252Cf source, prepared in a similar 10300 1 26 manner, was placed in the same position relative to a 10300 1 27 second surface barrier fission detector. The two 10300 1 28 sources, back-to-back, and their detectors were 10300 1 29 placed in a vacuum container in the center of a 10300 1 30 75-cm-diam. spherical Gd-loaded liquid scintillator 10300 1 31 tank having a l5-cm-diam. cylindrical hole through 10300 1 32 the center. The apparatus was placed in a low 10300 1 33 background room having thick concrete walls. 10300 1 34 Experimental data were collected for more than five 10300 1 35 months. During that time 10532 257Fm and 98659 252Cf 10300 1 36 fission events were detected. The 257Fm fission 10300 1 37 detection rate varied from 5.5 SF/h at the start of 10300 1 38 the experiment to 1.8 SF/h at the conclusion. From a 10300 1 39 least squares fit to the observed decay rate we 10300 1 40 obtained a value of 99.3 -+ 1.6 d for the half-life 10300 1 41 of 257Fm, in good agreement with the recently 10300 1 42 published value of 100.5 +- 0.2 d. 10300 1 43 ERR-ANALYS (DATA-ERR) No information on sources of uncertainties. 10300 1 44 STATUS (APRVD) Approved by author. 10300 1 45 DECAY-DATA (100-FM-257,99.3D,SF) 10300 1 46 HISTORY (19740529C) 10300 1 47 (19760204A) Data updated, reaction corrected 10300 1 48 (19830118A) Converted to reaction formalism 10300 1 49 (20011227A) Updated to new date formats, lower case. 10300 1 50 Units updated. 10300 1 51 (20191205A) BP: Added sample information, Cf, decay, 10300 1 52 the observed neutron probability distributions and 10300 1 53 MISC data. 10300 1 54 ENDBIB 52 0 10300 1 55 NOCOMMON 0 0 10300 1 56 ENDSUBENT 55 0 10300 199999 SUBENT 10300002 20191205 146310300 2 1 BIB 5 6 10300 2 2 REACTION (100-FM-257(0,F),PR,NU) 10300 2 3 MONITOR (98-CF-252(0,F),,NU) 10300 2 4 MISC-COL (MISC) Squared standard deviation of nu. 10300 2 5 STATUS (TABLE) Table II, page 194 of Physics+Chemistry of 10300 2 6 Fission Symp., Rochester 1973,vol.2,p.191. 10300 2 7 HISTORY (20191205A) BP: Added MISC data and status. 10300 2 8 ENDBIB 6 0 10300 2 9 NOCOMMON 0 0 10300 2 10 DATA 5 1 10300 2 11 DATA DATA-ERR MONIT MONIT-ERR MISC 10300 2 12 PRT/FIS PRT/FIS PRT/FIS PRT/FIS PRT/FIS 10300 2 13 3.77 0.02 3.735 0.014 2.49 10300 2 14 ENDDATA 3 0 10300 2 15 ENDSUBENT 14 0 10300 299999 SUBENT 10300003 20191205 146310300 3 1 BIB 4 5 10300 3 2 REACTION (98-CF-252(0,F),PR,NU) 10300 3 3 MISC-COL (MISC) Squared standard deviation of nu. 10300 3 4 STATUS (TABLE) Tables I-II, page 194 of Physics+Chemistry of 10300 3 5 Fission Symp., Rochester 1973,vol.2,p.191. 10300 3 6 HISTORY (20191205C) BP 10300 3 7 ENDBIB 5 0 10300 3 8 NOCOMMON 0 0 10300 3 9 DATA 3 1 10300 3 10 DATA DATA-ERR MISC 10300 3 11 PRT/FIS PRT/FIS PRT/FIS 10300 3 12 3.735 0.014 1.57 10300 3 13 ENDDATA 3 0 10300 3 14 ENDSUBENT 13 0 10300 399999 SUBENT 10300004 20200113 146310300 4 1 BIB 3 4 10300 4 2 REACTION (100-FM-257(0,F),PR/NUM,NU) 10300 4 3 STATUS (TABLE) Tables I, page 194 of Physics+Chemistry of 10300 4 4 Fission Symp., Rochester 1973,vol.2,p.191. 10300 4 5 HISTORY (20191205C) BP 10300 4 6 ENDBIB 4 0 10300 4 7 NOCOMMON 0 0 10300 4 8 DATA 3 10 10300 4 9 PART-OUT DATA DATA-ERR 10300 4 10 NO-DIM NO-DIM NO-DIM 10300 4 11 0.0 0.070 0.003 10300 4 12 1.0 0.176 0.004 10300 4 13 2.0 0.260 0.005 10300 4 14 3.0 0.261 0.005 10300 4 15 4.0 0.154 0.004 10300 4 16 5.0 0.061 0.003 10300 4 17 6.0 0.015 0.002 10300 4 18 7.0 0.003 0.001 10300 4 19 8.0 0.0001 0.0002 10300 4 20 9.0 0.0001 0.0001 10300 4 21 ENDDATA 12 0 10300 4 22 ENDSUBENT 21 0 10300 499999 SUBENT 10300005 20200113 146310300 5 1 BIB 3 4 10300 5 2 REACTION (98-CF-252(0,F),PR/NUM,NU) 10300 5 3 STATUS (TABLE) Tables I, page 194 of Physics+Chemistry of 10300 5 4 Fission Symp., Rochester 1973,vol.2,p.191. 10300 5 5 HISTORY (20191205C) BP 10300 5 6 ENDBIB 4 0 10300 5 7 NOCOMMON 0 0 10300 5 8 DATA 3 10 10300 5 9 PART-OUT DATA DATA-ERR 10300 5 10 NO-DIM NO-DIM NO-DIM 10300 5 11 0.0 0.041 0.001 10300 5 12 1.0 0.175 0.001 10300 5 13 2.0 0.308 0.002 10300 5 14 3.0 0.276 0.002 10300 5 15 4.0 0.146 0.001 10300 5 16 5.0 0.045 0.001 10300 5 17 6.0 0.008 0.0004 10300 5 18 7.0 0.001 0.0002 10300 5 19 8.0 0.0001 0.00006 10300 5 20 9.0 0.00001 0.00001 10300 5 21 ENDDATA 12 0 10300 5 22 ENDSUBENT 21 0 10300 599999 ENDENTRY 5 0 1030099999999