ENTRY 14294 20170731 14301429400000001 SUBENT 14294001 20170731 14301429400100001 BIB 5 6 1429400100002 TITLE Direct and Absolute Measurements of Average Fission 1429400100003 Neutron Yield from Uranium-235 and Californium-252 1429400100004 AUTHOR (A.De Volpi,K.G.Porges) 1429400100005 REFERENCE (C,66PARIS,1,297,1966) 1429400100006 INSTITUTE (1USAANL) 1429400100007 HISTORY (20170731C) BP 1429400100008 ENDBIB 6 0 1429400100009 NOCOMMON 0 0 1429400100010 ENDSUBENT 9 0 1429400199999 SUBENT 14294002 20170731 14301429400200001 BIB 8 22 1429400200002 REACTION (92-U-235(N,F),,NU,,MXW) Fission Counter #1. 1429400200003 FACILITY (REAC,1USAANL) Argonne CP-5 reactor thermal column. 1429400200004 DETECTOR (FISCH) Fission counter. 1429400200005 INC-SOURCE (REAC)(1.185+-0.007)*10**6 neutrons/sec. 1429400200006 METHOD (MANGB,COINC) The basic equipment for Phase I 1429400200007 consists of a fission counter containing material 1429400200008 which either fissions spontaneously or can be induced 1429400200009 to fission, a fast-acting neutron detector, and 1429400200010 electronic circuitry to record the number of single 1429400200011 and coincident events. Phase II consists of separate 1429400200012 measurement of the absolute neutron rate sing the 1429400200013 manganese bath. Adequate source rate is obtained by 1429400200014 adding a "booster foil" consisting of additional 1429400200015 enriched uranium place in the umbral region of the 1429400200016 chamber coating. The 235U fission counter and booster 1429400200017 are concentric hemispheres. 1429400200018 ANALYSIS The final computation for the neutron yield is a 1429400200019 simple division of the normalized neutron rate in 1429400200020 Phase II and the normalized fission rate of Phase I, 1429400200021 separately determined for each of the fission counters.1429400200022 ERR-ANALYS (DATA-ERR) No details on sources of uncertainties. 1429400200023 STATUS (TABLE) Table I, page 302. 1429400200024 ENDBIB 22 0 1429400200025 COMMON 1 3 1429400200026 DATA-ERR 1429400200027 PER-CENT 1429400200028 1.5 1429400200029 ENDCOMMON 3 0 1429400200030 DATA 2 1 1429400200031 EN-DUMMY DATA 1429400200032 EV PRT/FIS 1429400200033 0.0253 2.436 1429400200034 ENDDATA 3 0 1429400200035 ENDSUBENT 34 0 1429400299999 SUBENT 14294003 20170731 14301429400300001 BIB 8 22 1429400300002 REACTION (92-U-235(N,F),,NU,,MXW) Fission Counter #2. 1429400300003 FACILITY (REAC,1USAANL) Argonne CP-5 reactor thermal column. 1429400300004 INC-SOURCE (REAC)(1.185+-0.007)*10**6 neutrons/sec. 1429400300005 DETECTOR (FISCH) Fission counter. 1429400300006 METHOD (MANGB,COINC) The basic equipment for Phase I 1429400300007 consists of a fission counter containing material 1429400300008 which either fissions spontaneously or can be induced 1429400300009 to fission, a fast-acting neutron detector, and 1429400300010 electronic circuitry to record the number of single 1429400300011 and coincident events. Phase II consists of separate 1429400300012 measurement of the absolute neutron rate sing the 1429400300013 manganese bath. Adequate source rate is obtained by 1429400300014 adding a "booster foil" consisting of additional 1429400300015 enriched uranium place in the umbral region of the 1429400300016 chamber coating. The 235U fission counter and booster 1429400300017 are concentric hemispheres. 1429400300018 ANALYSIS The final computation for the neutron yield is a 1429400300019 simple division of the normalized neutron rate in 1429400300020 Phase II and the normalized fission rate of Phase I, 1429400300021 separately determined for each of the fission counters.1429400300022 ERR-ANALYS (DATA-ERR) No details on sources of uncertainties. 1429400300023 STATUS (TABLE) Table I, page 302. 1429400300024 ENDBIB 22 0 1429400300025 COMMON 1 3 1429400300026 DATA-ERR 1429400300027 PER-CENT 1429400300028 1.1 1429400300029 ENDCOMMON 3 0 1429400300030 DATA 2 1 1429400300031 EN-DUMMY DATA 1429400300032 EV PRT/FIS 1429400300033 0.0253 2.357 1429400300034 ENDDATA 3 0 1429400300035 ENDSUBENT 34 0 1429400399999 SUBENT 14294004 20170731 14301429400400001 BIB 4 11 1429400400002 REACTION (92-U-235(N,F),,NU,,MXW) 1429400400003 ANALYSIS The two values have been equally weighted in 1429400400004 averaging together, since 3.3% spread, which exceeds 1429400400005 the standard deviation assigned to each individual 1429400400006 counter, is probably dominated by discrepancies 1429400400007 associated with orientation of each fission counter, 1429400400008 an effect with equal a priori likelihood. 1429400400009 ERR-ANALYS (DATA-ERR) No details on sources of uncertainties. 1429400400010 STATUS (DEP,14294002) 1429400400011 (DEP,14294003) 1429400400012 (TABLE) Table III, page 305. 1429400400013 ENDBIB 11 0 1429400400014 NOCOMMON 0 0 1429400400015 DATA 3 1 1429400400016 EN-DUMMY DATA DATA-ERR 1429400400017 EV PRT/FIS PRT/FIS 1429400400018 0.0253 2.40 0.04 1429400400019 ENDDATA 3 0 1429400400020 ENDSUBENT 19 0 1429400499999 SUBENT 14294005 20170731 14301429400500001 BIB 6 18 1429400500002 REACTION (98-CF-252(0,F),PR,NU) 1429400500003 REL-REF (A,10166001,A.De Volpi,J,JNE,26,75,1972) 1429400500004 Additional measurements by the same authors. 1429400500005 DETECTOR (FISCH) Hemispherical foil counter. 1429400500006 METHOD (MANGB,COINC) The absence of reactor-induced neutron 1429400500007 background in the manganese bath favors the 1429400500008 californium measurements. Roughly half of a microgram 1429400500009 of 252Cf was deposited on a platinum disk used as one 1429400500010 electrode of parallel-plate fission chamber. The 1429400500011 geometry of the hemispherical counter does not permit 1429400500012 application of a simple theory (precise evaluation of 1429400500013 the fission rate), but its relatively high efficiency 1429400500014 (90%) suggests an extrapolation can be made to a 1429400500015 neutron detector with 2pi solid angle. 1429400500016 The neutron intensity was 7.277*10 n/sec (+-0.7%). 1429400500017 ERR-ANALYS (DATA-ERR) All quoted errors are one standard 1429400500018 deviation. 1429400500019 STATUS (TABLE) Table II, page 304. 1429400500020 ENDBIB 18 0 1429400500021 NOCOMMON 0 0 1429400500022 DATA 2 1 1429400500023 DATA DATA-ERR 1429400500024 PRT/FIS PRT/FIS 1429400500025 3.750 0.039 1429400500026 ENDDATA 3 0 1429400500027 ENDSUBENT 26 0 1429400599999 SUBENT 14294006 20170731 14301429400600001 BIB 6 20 1429400600002 REACTION (98-CF-252(0,F),PR,NU) 1429400600003 REL-REF (A,10166001,A.De Volpi,J,JNE,26,75,1972) 1429400600004 Additional measurements by the same authors. 1429400600005 DETECTOR (FISCH) Flat foil chamber. 1429400600006 METHOD (MANGB,COINC) The absence of reactor-induced neutron 1429400600007 background in the manganese bath favors the 1429400600008 californium measurements. Roughly half of a microgram 1429400600009 of 252Cf was deposited on a platinum disk used as one 1429400600010 electrode of parallel-plate fission chamber. The 1429400600011 strong correlation between fragment and neutron 1429400600012 emission results in a variation in a fission rate 1429400600013 determined by the coincidence method according to the 1429400600014 angle between the fission foil axis and the neutron 1429400600015 detector normal. A simple theory allows a relatively 1429400600016 precise evaluation of the fission rate from these 1429400600017 data. 1429400600018 The neutron intensity was 5.15*10**5 n/sec (+-1.8%). 1429400600019 ERR-ANALYS (DATA-ERR) All quoted errors are one standard 1429400600020 deviation. 1429400600021 STATUS (TABLE) Table II, page 304. 1429400600022 ENDBIB 20 0 1429400600023 NOCOMMON 0 0 1429400600024 DATA 2 1 1429400600025 DATA DATA-ERR 1429400600026 PRT/FIS PRT/FIS 1429400600027 3.748 0.095 1429400600028 ENDDATA 3 0 1429400600029 ENDSUBENT 28 0 1429400699999 SUBENT 14294007 20170731 14301429400700001 BIB 4 12 1429400700002 REACTION (98-CF-252(0,F),PR,NU,,AV) 1429400700003 ANALYSIS The neutron yield per fission is calculated from the 1429400700004 data separately for the hemispherical counter and 1429400700005 flat foil chamber. The two results are weighted with 1429400700006 inverse variances. 1429400700007 ERR-ANALYS (DATA-ERR) It was decided to increase 0.1% standard 1429400700008 error obtained in the angular scan to 0.5%, providing 1429400700009 an over-all weighted error in the fission rate of 1429400700010 0.4%. All quoted errors are one standard deviation. 1429400700011 STATUS (DEP,14294005) 1429400700012 (DEP,14294006) 1429400700013 (TABLE) Table III, page 305. 1429400700014 ENDBIB 12 0 1429400700015 NOCOMMON 0 0 1429400700016 DATA 2 1 1429400700017 DATA DATA-ERR 1429400700018 PRT/FIS PRT/FIS 1429400700019 3.750 0.028 1429400700020 ENDDATA 3 0 1429400700021 ENDSUBENT 20 0 1429400799999 ENDENTRY 7 0 1429499999999