ENTRY 14296 20170802 14301429600000001 SUBENT 14296001 20170802 14301429600100001 BIB 7 14 1429600100002 TITLE The value of nu for fission spectrum induced and 1429600100003 spontaneous fission of 238U 1429600100004 AUTHOR (R.Sher,J.Leroy) 1429600100005 REFERENCE (J,JNE/A,12,101,1960) 1429600100006 #doi:10.1016/0368-3265(60)90071-2 1429600100007 INSTITUTE (1USABNL,2FR SAC) 1429600100008 FACILITY (REAC,1USABNL) 1429600100009 SAMPLE The scatterers consisted of solid cylindrical bars of 1429600100010 uranium metal, 3.0 cm in diameter by 35 cm long. Two 1429600100011 enrichments were available to us, namely natural 1429600100012 uranium (0.71% 235U) and slightly enriched 1429600100013 uranium (0.92% 235U). The dummy scatterer was 1429600100014 a bismuth cylinder of similar dimensions. 1429600100015 HISTORY (20170802C) BP 1429600100016 ENDBIB 14 0 1429600100017 NOCOMMON 0 0 1429600100018 ENDSUBENT 17 0 1429600199999 SUBENT 14296002 20170802 14301429600200001 BIB 8 29 1429600200002 REACTION (92-U-238(N,F),,NU,,FIS) 1429600200003 INC-SOURCE (REAC) The total intensity of the fast beam at the 1429600200004 center of the detection system was about 2*10**3 n/sec.1429600200005 INC-SPECT A beam of piled neutrons 4 cm2 emerging from the EL.2 1429600200006 reactor. The fast beam emerging at 90 degrees to the 1429600200007 thermal beam is collimated by a hole 100 cm long by 1429600200008 2.5 cm in diameter placed in a large tank of water. 1429600200009 DETECTOR (BF3) The detection system consisted of BF3, 1429600200010 proportional counters embedded in paraffin and placed 1429600200011 along two circles approximately concentric with the 1429600200012 axis of the beam. They were well shielded by 1429600200013 additional water, paraffin, boron and cadmium. 1429600200014 METHOD A beam of pile neutrons 4 cm2 emerging from the 1429600200015 reactor strikes a 3 mm thick uranium converter plate, 1429600200016 enriched to 20 per cent in 235U. The fast beam 1429600200017 emerging at 90 degrees to the thermal beam is 1429600200018 collimated by a hole 100 cm long by 2.5 cm in 1429600200019 diameter placed in a large tank of water. Emerging 1429600200020 from the collimator it passes through a cavity in a 1429600200021 large paraffin cylinder containing the neutron 1429600200022 detection system. Scatterers could be inserted in 1429600200023 this cavity, along the beam axis. 1429600200024 ERR-ANALYS (DATA-ERR) Random errors of positioning, counting 1429600200025 statistics and uncertainties in the size of the 1429600200026 systematic corrections. 1429600200027 CORRECTION Corrected for inelastic scattering and delayed 1429600200028 neutrons, plus by extrapolating the intensity to zero 1429600200029 235U enrichment. 1429600200030 STATUS (TABLE) page 104. 1429600200031 ENDBIB 29 0 1429600200032 COMMON 2 3 1429600200033 EN-MEAN EN-ERR 1429600200034 MEV MEV 1429600200035 2.8 0.15 1429600200036 ENDCOMMON 3 0 1429600200037 DATA 2 1 1429600200038 DATA DATA-ERR 1429600200039 PRT/FIS PRT/FIS 1429600200040 2.87 0.35 1429600200041 ENDDATA 3 0 1429600200042 ENDSUBENT 41 0 1429600299999 SUBENT 14296003 20170802 14301429600300001 BIB 10 49 1429600300002 REACTION (92-U-238(N,F),,NU,,FIS) 1429600300003 INC-SOURCE (REAC) The total intensity of the fast beam at the 1429600300004 center of the detection system was about 2*10**3 n/sec.1429600300005 INC-SPECT A beam of piled neutrons 4 cm2 emerging from the EL.2 1429600300006 reactor. The fast beam emerging at 90 degrees to the 1429600300007 thermal beam is collimated by a hole 100 cm long by 1429600300008 2.5 cm in diameter placed in a large tank of water. 1429600300009 DETECTOR (BF3,FISCH) The detection system consisted of BF3, 1429600300010 proportional counters embedded in paraffin and placed 1429600300011 along two circles approximately concentric with the 1429600300012 axis of the beam. They were well shielded by 1429600300013 additional water, paraffin, boron and cadmium. The 1429600300014 fission chamber used in the coincidence measurements 1429600300015 consisted of 19 parallel plates of aluminum coated 1429600300016 on both sides (except for the end plates) with 1429600300017 natural uranium oxide to a nominal thickness of 1 1429600300018 mg/cm2. The chamber was filled with a mixture of 95% 1429600300019 Ar and 5% CO2, at atmospheric pressure. 1429600300020 METHOD (COINC) A beam of pile neutrons 4 cm2 emerging from 1429600300021 the reactor strikes a 3 mm thick uranium converter 1429600300022 plate, enriched to 20 per cent in 235U. The fast beam 1429600300023 emerging at 90 degrees to the thermal beam is 1429600300024 collimated by a hole 100 cm long by 2.5 cm in 1429600300025 diameter placed in a large tank of water. Emerging 1429600300026 from the collimator it passes through a cavity in a 1429600300027 large paraffin cylinder containing the neutron 1429600300028 detection system. The coincidence rate between 1429600300029 fissions occurring in a fission chamber placed in the 1429600300030 beam and the secondary neutrons detected by the BF3, 1429600300031 counter assembly. A fission chamber using natural 1429600300032 uranium was used. The thermal neutron beam for 1429600300033 inducing fission in the 235U of the chamber was 1429600300034 obtained by replacing the converter plate by a 1429600300035 paraffin block which scattered the pile neutrons into 1429600300036 the collimating system. A simple mechanical 1429600300037 arrangement made it possible to have either the fast 1429600300038 beam, thermal beam or no beam. 1429600300039 ERR-ANALYS (DATA-ERR) Most of the experimental error is due to the1429600300040 counting statistics. 1429600300041 CORRECTION A small correction due to spontaneous fission in 238U 1429600300042 was applied to the final result. A correction for the 1429600300043 17 per cent fission fraction due to 235U with the 1429600300044 fast beam was also applied. Finally, the result has 1429600300045 been corrected for the degradation of the neutron 1429600300046 spectrum in the beam. The the value of the overall 1429600300047 correction for anisotropy turned out to be 2.0+-0.5%. 1429600300048 MONITOR (92-U-235(N,F),,NU) 1429600300049 MONIT-REF ((MONIT),D.J.Hughes+,P,BNL-325,1958) 1429600300050 STATUS (TABLE) page 105. 1429600300051 ENDBIB 49 0 1429600300052 COMMON 3 3 1429600300053 MONIT EN-MEAN EN-ERR 1429600300054 PRT/FIS MEV MEV 1429600300055 2.47 2.8 0.15 1429600300056 ENDCOMMON 3 0 1429600300057 DATA 2 1 1429600300058 DATA DATA-ERR 1429600300059 PRT/FIS PRT/FIS 1429600300060 2.93 0.075 1429600300061 ENDDATA 3 0 1429600300062 ENDSUBENT 61 0 1429600399999 SUBENT 14296004 20170802 14301429600400001 BIB 8 32 1429600400002 REACTION (92-U-238(0,F),,NU) 1429600400003 DETECTOR (BF3,FISCH) The detection system consisted of BF3, 1429600400004 proportional counters embedded in paraffin and placed 1429600400005 along two circles approximately concentric with the 1429600400006 axis of the beam. They were well shielded by 1429600400007 additional water, paraffin, boron and cadmium. The 1429600400008 fission chamber used in the coincidence measurements 1429600400009 consisted of 19 parallel plates of aluminum coated 1429600400010 on both sides (except for the end plates) with 1429600400011 natural uranium oxide to a nominal thickness of 1 1429600400012 mg/cm2. The chamber was filled with a mixture of 95% 1429600400013 Ar and 5% CO2, at atmospheric pressure. 1429600400014 METHOD (COINC) A beam of pile neutrons 4 cm2 emerging from 1429600400015 the reactor strikes a 3 mm thick uranium converter 1429600400016 plate, enriched to 20 per cent in 235U. The fast beam 1429600400017 emerging at 90 degrees to the thermal beam is 1429600400018 collimated by a hole 100 cm long by 2.5 cm in 1429600400019 diameter placed in a large tank of water. Emerging 1429600400020 from the collimator it passes through a cavity in a 1429600400021 large paraffin cylinder containing the neutron 1429600400022 detection system. The spontaneous fission of 238U was 1429600400023 easily obtained by measuring the fission and 1429600400024 coincidence rates in the absence of primary neutrons. 1429600400025 ERR-ANALYS (DATA-ERR) Most of the experimental error is due to the1429600400026 counting statistics. 1429600400027 CORRECTION Calculated or measured corrections for alpha-pile-up, 1429600400028 stray thermal neutron induced fission in 238U, 1429600400029 accidental coincidences, etc., were negligible, their 1429600400030 combined value being under 1%. 1429600400031 MONITOR (92-U-235(N,F),,NU) 1429600400032 MONIT-REF ((MONIT),D.J.Hughes+,P,BNL-325,1958) 1429600400033 STATUS (TABLE) page 105. 1429600400034 ENDBIB 32 0 1429600400035 COMMON 1 3 1429600400036 MONIT 1429600400037 PRT/FIS 1429600400038 2.47 1429600400039 ENDCOMMON 3 0 1429600400040 DATA 2 1 1429600400041 DATA DATA-ERR 1429600400042 PRT/FIS PRT/FIS 1429600400043 2.10 0.08 1429600400044 ENDDATA 3 0 1429600400045 ENDSUBENT 44 0 1429600499999 ENDENTRY 4 0 1429699999999