ENTRY 14299 20170822 14331429900000001 SUBENT 14299001 20170822 14331429900100001 BIB 10 33 1429900100002 TITLE Distribution of the Number of Prompt Neutrons from 1429900100003 the Spontaneous Fission of Pu240 1429900100004 AUTHOR (J.E.Hammel,J.F.Kephart) 1429900100005 REFERENCE (J,PR,100,190,1955) 1429900100006 #doi:10.1103/PhysRev.100.190 1429900100007 INSTITUTE (1USALAS) 1429900100008 DETECTOR (STANK,FISCH) A large liquid scintillator of high 1429900100009 efficiency for the detection of neutrons. Neutrons are 1429900100010 detected by cadmium capture gamma-ray pulses in the 1429900100011 liquid scintillator. The detector consisted of a 1429900100012 cylindrical tank 16 inches high and 16 inches in 1429900100013 diameter with 32 DuMont 1177 photomultiplier tubes. 1429900100014 The detector was filled with toluene loaded to 4 g 1429900100015 per liter with p-terphenyl. It used a wavelength 1429900100016 shifter of POPOP and was loaded with cadmium in the 1429900100017 form of cadmium octoate to a concentration of 0.0025 1429900100018 cadmium atoms per hydrogen atom. 1429900100019 METHOD (COINC,PHD) A 45-microgram Pu240 sample was placed on 1429900100020 a foil in a small parallel plate fission chamber at 1429900100021 the center of the scintillator tank. A fission pulse 1429900100022 from the fission chamber was used to initiate the 1429900100023 process of recording the liquid scintillator output. 1429900100024 By using 2.20+-0.03 for the average number of prompt 1429900100025 neutrons per spontaneous fission of Pu240 the 1429900100026 efficiency of the scintillation detector for fission 1429900100027 spectrum neutrons was determined. The efficiency, 1429900100028 alpha, thus obtained was, together with its probable 1429900100029 error, 0.716+-0.012. 1429900100030 CORRECTION Corrections for finite resolving time and background 1429900100031 pulses. 1429900100032 MONITOR (94-PU-240(0,F),PR,NU) = 2.20+-0.03) 1429900100033 MONIT-REF ((MONIT),J.Terrell+,W,Terrell,1955) 1429900100034 HISTORY (20170822C) BP 1429900100035 ENDBIB 33 0 1429900100036 COMMON 2 3 1429900100037 MONIT MONIT-ERR 1429900100038 PRT/FIS PRT/FIS 1429900100039 2.20 0.03 1429900100040 ENDCOMMON 3 0 1429900100041 ENDSUBENT 40 0 1429900199999 SUBENT 14299002 20170822 14331429900200001 BIB 3 10 1429900200002 REACTION (94-PU-240(0,F),PR/NUM,NU) 1429900200003 ERR-ANALYS (DATA-ERR) The probable errors attached to the 1429900200004 emission probabilities in Table I were obtained by 1429900200005 calculating the effect of independent variations in 1429900200006 the parameters used in calculating the emission 1429900200007 probabilities. The root sum square of the variations 1429900200008 in the emission probabilities caused by one 1429900200009 standard deviation in the parameters gave the 1429900200010 standard deviation in the emission probabilities. 1429900200011 STATUS (TABLE) Table I, page 192. 1429900200012 ENDBIB 10 0 1429900200013 NOCOMMON 0 0 1429900200014 DATA 3 7 1429900200015 PART-OUT DATA DATA-ERR 1429900200016 NO-DIM NO-DIM NO-DIM 1429900200017 0. 0.062 0.006 1429900200018 1. 0.198 0.017 1429900200019 2. 0.374 0.022 1429900200020 3. 0.228 0.024 1429900200021 4. 0.114 0.022 1429900200022 5. 0.027 0.013 1429900200023 6. 0.000 0.005 1429900200024 ENDDATA 9 0 1429900200025 ENDSUBENT 24 0 1429900299999 ENDENTRY 2 0 1429999999999