ENTRY 13913 20240314 150713913000 1 SUBENT 13913001 20240314 150713913001 1 BIB 10 21 13913001 2 AUTHOR (J.A.Grundl) 13913001 3 TITLE Measurement of the Average Fission Cross-Section 13913001 4 Ratio, sigmaF(235U)/sigmaF(238U) for 235U and 239Pu 13913001 5 Fission Neutrons 13913001 6 REFERENCE (C,71VIENNA,,107,1971) 13913001 7 REL-REF (N,10304001,J.A.Grundl+,J,ANS,15,945,1972) 13913001 8 Measurements with 252Cf neutron source. 13913001 9 INSTITUTE (1USANBS) 13913001 10 FACILITY (REAC,1USANBS) 13913001 11 SAMPLE (92-U-235,ENR=0.997) Two foils: Enriched and natural 13913001 12 uranium, 200 microg/cm2 thick. 13913001 13 DETECTOR (IOCH) 13913001 14 MONITOR (92-U-235(N,F),,SIG) Run to run thermal neutron flux 13913001 15 levels in the cavity were monitored with a commercial 13913001 16 235U fission chamber exposed to a beam taken of the 13913001 17 front face of the thermal column. A triple scaler 13913001 18 arrangement was also used to record pulses from this 13913001 19 monitor chamber. 13913001 20 HISTORY (20140804C) BP 13913001 21 (20230604A) OS. Uncertainties modified in subs.2,3 13913001 22 (20240314A) On. Major alterations in 002. 13913001 23 ENDBIB 21 0 13913001 24 NOCOMMON 0 0 13913001 25 ENDSUBENT 24 0 1391300199999 SUBENT 13913002 20240314 150713913002 1 BIB 7 20 13913002 2 REACTION ((92-U-235(N,F),,SIG,,FIS)/(92-U-238(N,F),,SIG,,FIS)) 13913002 3 STATUS (TABLE,,J.A.Grundl,C,71VIENNA,,107,1971) page 108. 13913002 4 METHOD (PHD) 13913002 5 INC-SOURCE Fission rates were observed with 235U fission 13913002 6 neutrons source. 13913002 7 INC-SPECT Energy of 235U fission neutrons is not listed in the 13913002 8 article. We can assume average fission neutrons 13913002 9 energy of ~2 MeV. 13913002 10 ERR-ANALYS (ERR-T) Uncertainties are due to: 13913002 11 (ERR-S) counting statistics - 0.3%. 13913002 12 (ERR-1) thermal column monitor stability - 0.6%. 13913002 13 (ERR-2) source-detector position - 2%. 13913002 14 (ERR-3) cavity position - 1.2%. 13913002 15 (ERR-4) reactor background - 2%. 13913002 16 (ERR-5) cavity return background - 2.5%. 13913002 17 (ERR-6) relative detector efficiency - 0.3%. 13913002 18 (ERR-7) intrinsic source-detector scattering - 1.5%. 13913002 19 (ERR-8) foil weight ratio - 2%. 13913002 20 HISTORY (20230604A) ERR-T in DATA section deleted 13913002 21 (20240314A) On. EN-DUMMY=2.0 MeV -> KT-DUMMY=1.32 MeV 13913002 22 ENDBIB 20 0 13913002 23 COMMON 10 6 13913002 24 ERR-T ERR-S ERR-1 ERR-2 ERR-3 ERR-4 13913002 25 ERR-5 ERR-6 ERR-7 ERR-8 13913002 26 PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT 13913002 27 PER-CENT PER-CENT PER-CENT PER-CENT 13913002 28 4.7 0.3 0.6 2.0 1.2 2.013913002 29 2.5 0.3 1.5 2.0 13913002 30 ENDCOMMON 6 0 13913002 31 DATA 2 1 13913002 32 KT-DUMMY DATA 13913002 33 MEV NO-DIM 13913002 34 1.32 3.71 13913002 35 ENDDATA 3 0 13913002 36 ENDSUBENT 35 0 1391300299999 SUBENT 13913003 20230707 150713913003 1 BIB 8 23 13913003 2 REACTION (((92-U-235(N,F),,SIG,,FIS)/ 13913003 3 (92-U-238(N,F),,SIG,,FIS))// 13913003 4 ((92-U-235(N,F),,SIG,,FIS)/(92-U-238(N,F),,SIG,,FIS))) 13913003 5 STATUS (TABLE,,J.A.Grundl,C,71VIENNA,,107,1971) page 108. 13913003 6 METHOD (PHD) 13913003 7 INC-SOURCE Fission rates were observed with 235U (denominator 13913003 8 ratio) and 239Pu (nominator ratio) fission neutron 13913003 9 sources. 13913003 10 INC-SPECT Energies of 235U and 239Pu fission neutrons are not 13913003 11 listed in the article. We can assume that 235U and 13913003 12 239Pu average fission neutrons energies are ~2 and 13913003 13 ~2.1 MeV, respectively. 13913003 14 COMMENT From the knowledge of 235U fission source ratio of 13913003 15 3.71 and 239Pu/235U sources ratio of 9.70, one may 13913003 16 reconstruct a fission cross section ratio for a pure 13913003 17 239Pu source as 3.5987 +- 0.1704. 13913003 18 ERR-ANALYS (ERR-T) Uncertainties are due to: 13913003 19 (ERR-S) counting statistics - 0.4%. 13913003 20 (ERR-1) thermal column monitor stability - 0.6%. 13913003 21 (ERR-2) source-detector position - 0.7%. 13913003 22 (ERR-3) cavity position - 0.5%. 13913003 23 (ERR-4) reactor background - 0.6%. 13913003 24 HISTORY (20230604A) ERR-T in DATA section deleted 13913003 25 ENDBIB 23 0 13913003 26 COMMON 6 3 13913003 27 ERR-T ERR-S ERR-1 ERR-2 ERR-3 ERR-4 13913003 28 PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT 13913003 29 1.3 0.4 0.6 0.7 0.5 0.613913003 30 ENDCOMMON 3 0 13913003 31 DATA 3 1 13913003 32 EN-DUM-NM EN-DUM-DN DATA 13913003 33 MEV MEV NO-DIM 13913003 34 2.1 2.0 0.970 13913003 35 ENDDATA 3 0 13913003 36 ENDSUBENT 35 0 1391300399999 ENDENTRY 3 0 1391399999999