ENTRY 23610 20231213 23212361000000001 SUBENT 23610001 20231213 23212361000100001 BIB 15 64 2361000100002 TITLE Neutron capture cross-section measurement by mass 2361000100003 spectrometry for Pb-204 irradiated in JRR-3 2361000100004 AUTHOR (S.Nakamura,Y.Shibahara,A.Kimura,S.Endo,T.Shizuma) 2361000100005 INSTITUTE (2JPNJAE,2JPNKTO,2JPNIRS) 2361000100006 REFERENCE (J,NST,60,1133,2023) 2361000100007 #doi:10.1080/00223131.2023.2172088 2361000100008 FACILITY (REAC,2JPNJAE) 2361000100009 The Japan Research Reactor-3 (JRR-3) in JAEA. 2361000100010 INC-SOURCE (REAC) The HR-2 irradiation hole in JRR-3. 2361000100011 The proportion of epi-thermal neutron flux component to2361000100012 total neutron flux was less than 1%. 2361000100013 The HR can be considered as a well-thermalized neutron 2361000100014 field. 2361000100015 SAMPLE An enriched 204Pb metal sample with a mass of 15.13 2361000100016 mg was used for a Pb sample. 2361000100017 Two sets of two Au/Al alloy wires with weights of 2361000100018 0.5 mg and 1.0 mg and a 1.2 mg Mo metal foil was 2361000100019 used as a neutron flux monitor. 2361000100020 One of the monitors was irradiated for 30 minutes. 2361000100021 Subsequently, the Pb sample was irradiated 2361000100022 for 576 hours (24 days). 2361000100023 After the irradiation of the Pb sample, the other 2361000100024 monitor was irradiated for 30 minutes. 2361000100025 METHOD (ACTIV,ASEP,GSPEC) The enriched 204Pb sample was 2361000100026 irradiated for a long period with thermal neutrons 2361000100027 in the JRR-3. 2361000100028 After irradiation, the sample was analysed by thermal 2361000100029 ionization mass spectrometry (TIMS) technique. 2361000100030 The thermal neutron capture cross section of 204Pb was 2361000100031 determined from the isotopic ratio between 205Pb and 2361000100032 204Pb and measured neutron flux. 2361000100033 The neutron flux components were derived from the 2361000100034 gamma-ray spectral data of the flux monitors. 2361000100035 DETECTOR (MAGSP,HPGE) The isotopic ratios of Pb sample were 2361000100036 analysed by TIMS. The mass analysis was performed 2361000100037 using the mass spectrometer TRITON-T1 (Thermo 2361000100038 Fisher Scientific,Inc. USA). The decay gamma-rays 2361000100039 from the monitors were measured with a high purity 2361000100040 germanium detector, relative efficiency of 20%. 2361000100041 ANALYSIS The net isotopic ratio 205Pb/204Pb was derived with 2361000100042 TIMS. 2361000100043 The neutron flux was derived with the Westcott 2361000100044 convention method using the gamma-ray yields, 2361000100045 the thermal cross section of Au, the sensitivity to 2361000100046 epi-thermal neutrons, and the g-factors of the monitor 2361000100047 materials. 2361000100048 These values were taken from the REL-REF. 2361000100049 The thermal cross section of Mo-37 was taken from 2361000100050 an Authors' previous experiment. (Not published yet.) 2361000100051 The deduced Westcott index is enough small and the 2361000100052 epithermal component was negligibly small. 2361000100053 The influences of double neutron capture events and 2361000100054 decay events of 205Pb were also negligible. 2361000100055 The thermal neutron capture cross section of 204Pb was 2361000100056 determined from the isotopic ratio between 205Pb and 2361000100057 204Pb and derived neutron flux. 2361000100058 REL-REF (R,,S.F.Mughabghab,B,NEUT.RES,,,2018) 2361000100059 DECAY-DATA (79-AU-198-G,2.6943D,DG,411.80,0.9562) 2361000100060 (42-MO-99,2.749D,DG,739.5,0.1213) 2361000100061 ASSUMED (ASSUM1,42-MO-98(N,G)42-MO-99,,SIG) Thermal C.S. 2361000100062 (ASSUM2,79-AU-197(N,G)79-AU-198,,SIG) Thermal C.S. 2361000100063 ERR-ANALYS (ASSUM1-ERR) Uncertainty of Mo-98 thermal C.S. 2361000100064 (ASSUM2-ERR) Uncertainty of Au-197 thermal C.S. 2361000100065 HISTORY (20231213C) By A. Kimura 2361000100066 ENDBIB 64 0 2361000100067 COMMON 4 3 2361000100068 ASSUM1 ASSUM2 ASSUM1-ERR ASSUM2-ERR 2361000100069 B B B B 2361000100070 98.65 0.134 0.09 0.003 2361000100071 ENDCOMMON 3 0 2361000100072 ENDSUBENT 71 0 2361000199999 SUBENT 23610002 20231213 23212361000200001 BIB 3 7 2361000200002 REACTION (82-PB-204(N,G)82-PB-205,,SIG) 2361000200003 ERR-ANALYS (ERR-T) Total Uncertainty. 2361000200004 (ERR-1) Uncertainty due to deduced neutron flux. 2361000200005 7.57 +- 0.27 x 10E+13 [n/cm2/sec] 2361000200006 (ERR-2) Uncertainty due to deduced reaction ratio. 2361000200007 4.06 +- 0.18 x 10E-11 [1/sec] 2361000200008 STATUS (TABLE,,S.Nakamura+,J,NST,60,1133,2023) Table 7 2361000200009 ENDBIB 7 0 2361000200010 COMMON 2 3 2361000200011 ERR-1 ERR-2 2361000200012 PER-CENT PER-CENT 2361000200013 3.6 4.4 2361000200014 ENDCOMMON 3 0 2361000200015 DATA 3 1 2361000200016 EN DATA ERR-T 2361000200017 EV B B 2361000200018 0.0253 0.536 0.030 2361000200019 ENDDATA 3 0 2361000200020 ENDSUBENT 19 0 2361000299999 ENDENTRY 2 0 2361099999999