ENTRY 12395 20201210 14761239500000001 SUBENT 12395001 20201210 14761239500100001 BIB 10 36 1239500100002 TITLE Number of Neutrons per Fission for 25 and 49 1239500100003 AUTHOR (T.M.Snyder,R.W.Williams) 1239500100004 REFERENCE (R,LA-102,1944) 1239500100005 INSTITUTE (1USALAS) 1239500100006 FACILITY (CYCLO,1USALAS) 1239500100007 INC-SPECT The thermal flux which is available well back in the 1239500100008 graphite block, using the cyclotron as a neutron 1239500100009 source. 1239500100010 METHOD The number of fast neutrons given off was measured by 1239500100011 making a volume integral of the resonance activity 1239500100012 acquired by indium foils and comparing this with a 1239500100013 similar integral from a Ra-Be source of known output; 1239500100014 the number of fissions was measured by counting the 1239500100015 fissions from a thin foil on the face of a case 1239500100016 containing the sample of fissionable material, and 1239500100017 knowing the ratio of weights of material in the foil 1239500100018 to material in the sample. The measurement gives a 1239500100019 rather accurate value of the ratio nubar/Q where Q is 1239500100020 the neutron output of Ra-Be source. 1239500100021 CORRECTION The self absorption correction was calculated on the 1239500100022 basis of this average counting rate plus the 1239500100023 assumption of an isotropic neutron flux around the 1239500100024 sample. The straight-through self-absorption in the 1239500100025 sample was about 11 percent in the worst case (round 1239500100026 25 sample); it becomes larger when averaged over all 1239500100027 angles, but is partially monitored by the detector 1239500100028 foil, one side of which is shaded by the sample. The 1239500100029 net correction was 5 percent for the round 25 sample. 1239500100030 COMMENT Compiler's comment: Los Alamos notation uses 49 for 1239500100031 Z=94, A=239 (239Pu) and 25 for Z=92, A=235 (235U). 1239500100032 HISTORY (19760804T) Translated from SCISRS. 1239500100033 (19820519A) Converted to reaction formalism 1239500100034 (20201210A) BP: Added 239Pu/235U or 49/25 ratio data, 1239500100035 corrected units, ALF->ETA, updated to new date formats,1239500100036 lower case. Corrections according last EXFOR rules and1239500100037 Dict. 1239500100038 ENDBIB 36 0 1239500100039 COMMON 1 3 1239500100040 EN-DUMMY 1239500100041 EV 1239500100042 0.0253 1239500100043 ENDCOMMON 3 0 1239500100044 ENDSUBENT 43 0 1239500199999 SUBENT 12395002 20201210 14761239500200001 BIB 3 7 1239500200002 REACTION (92-U-235(N,F),,NU,,SPA) 1239500200003 SAMPLE The 25 foils from material of the same isotopic 1239500200004 constitution as weighing 25 samples (E-10 oxide). 1239500200005 Direct weighing of these foils proved unreliable, 1239500200006 apparently because their large areas encourage the 1239500200007 deposition of impurities. 1239500200008 STATUS (TABLE) page 18. 1239500200009 ENDBIB 7 0 1239500200010 NOCOMMON 0 0 1239500200011 DATA 1 1 1239500200012 DATA 1239500200013 PRT/FIS 1239500200014 2.44 1239500200015 ENDDATA 3 0 1239500200016 ENDSUBENT 15 0 1239500299999 SUBENT 12395003 20201210 14761239500300001 BIB 3 11 1239500300002 REACTION (94-PU-239(N,F),,NU,,SPA) 1239500300003 SAMPLE For 49 the thin foil was made by transferring 1239500300004 quantitatively an aliquot of the total sample on to a 1239500300005 thin platinum disk. The value thus obtained was 1239500300006 checked by comparing the fission counts from this 1239500300007 foil with the fission mounts from a very small 49 1239500300008 foil which had been alpha-counted accurately; and 1239500300009 alpha-counting a very small aliquot from the total 1239500300010 sample (note that the ratio is independent of the 1239500300011 specific activity of 49). 1239500300012 STATUS (TABLE) page 18. 1239500300013 ENDBIB 11 0 1239500300014 NOCOMMON 0 0 1239500300015 DATA 1 1 1239500300016 DATA 1239500300017 PRT/FIS 1239500300018 2.86 1239500300019 ENDDATA 3 0 1239500300020 ENDSUBENT 19 0 1239500399999 SUBENT 12395004 20201210 14761239500400001 BIB 3 3 1239500400002 REACTION (94-PU-239(N,ABS),,ETA,,SPA) 1239500400003 ASSUMED (ASSUM,94-PU-239(N,ABS),,SIG) 1239500400004 STATUS (TABLE) pages 2-3,24. 1239500400005 ENDBIB 3 0 1239500400006 NOCOMMON 0 0 1239500400007 DATA 2 1 1239500400008 DATA ASSUM 1239500400009 PRT/INC B 1239500400010 0.44 1057. 1239500400011 ENDDATA 3 0 1239500400012 ENDSUBENT 11 0 1239500499999 SUBENT 12395005 20201210 14761239500500001 BIB 4 5 1239500500002 REACTION (92-U-235(N,ABS),,ETA,,SPA) 1239500500003 ASSUMED (ASSUM,92-U-235(N,G)92-U-236,,SIG) 1239500500004 HISTORY (20201210A) BP: Corrected assumed from 2.16 to 644 b. 1239500500005 Changed ALF to ETA. 1239500500006 STATUS (TABLE) page 2-3. 1239500500007 ENDBIB 5 0 1239500500008 NOCOMMON 0 0 1239500500009 DATA 2 1 1239500500010 DATA ASSUM 1239500500011 PRT/INC B 1239500500012 0.13 644.0 1239500500013 ENDDATA 3 0 1239500500014 ENDSUBENT 13 0 1239500599999 SUBENT 12395006 20201211 14761239500600001 BIB 4 8 1239500600002 REACTION ((94-PU-239(N,F),,NU,,SPA)/(92-U-235(N,F),,NU,,SPA)) 1239500600003 ERR-ANALYS (DATA-ERR) Authors attempted to assign reasonable 1239500600004 probable errors to these correction factors, and have 1239500600005 considered the errors in mass ratios. 1239500600006 HISTORY (20201210C) BP 1239500600007 STATUS (DEP,12395003) 1239500600008 (DEP,12395002) 1239500600009 (TABLE) page 18. 1239500600010 ENDBIB 8 0 1239500600011 NOCOMMON 0 0 1239500600012 DATA 2 1 1239500600013 DATA DATA-ERR 1239500600014 NO-DIM NO-DIM 1239500600015 1.17 0.02 1239500600016 ENDDATA 3 0 1239500600017 ENDSUBENT 16 0 1239500699999 ENDENTRY 6 0 1239599999999