ENTRY 23515 20230517 2351500000001 SUBENT 23515001 20230517 20231011 2351500100001 BIB 12 41 2351500100002 TITLE A measurement of the thermal neutron radiative 2351500100003 capture cross section of 238U 2351500100004 AUTHOR (J.B.Hunt, J.C.Robertson, T.B.Ryves) 2351500100005 REFERENCE (J,JNE,23,705,1969) 2351500100006 REL-REF (I,,T.B.Ryves+,J,JNE,22,759,1968) 2351500100007 Facility details. 2351500100008 (R,,K.J.Blinowska+,J,NP,55,331,1964) 2351500100009 Decay scheme 2351500100010 (modified to take into account data of Mackenzie+) 2351500100011 (R,,D.R.Mackenzie+,J,NP/A,108,81,1968) U-239 decay data2351500100012 (R,11525001,W.H.Walker+,J,CJP,38,57,1960) 2351500100013 Correction term W 2351500100014 INSTITUTE (2UK NPL) 2351500100015 FACILITY (VDG,2UK NPL) NPL standard thermal neutron flux 2351500100016 facility. 2351500100017 INC-SOURCE (D-BE) 2351500100018 INC-SPECT Thermal neutrons. 2351500100019 Neutron flux was measured by Au foils of 2.2 cm 2351500100020 diameter, 10 mg/cm2 thickness irradiated in 2 cm 2351500100021 position simultaneously with U to be 2351500100022 (4.46+-0.40%) x10**7 n/sec/cm2 in position 2, 2351500100023 (3.98+-0.55%) x10**7 n/cm2/sec in position 22. 2351500100024 DETECTOR (D4PI) 4PI beta proportional counter. 2351500100025 Efficiency of 1.21 MeV beta decay branch was determined2351500100026 by counting coincidences between beta and 75 keV gamma.2351500100027 Stability of beta counter was checked by standard Co-602351500100028 source. 75 keV gamma-ray gate was checked and reset 2351500100029 daily by gamma-ray spectrum of irradiated natural U . 2351500100030 (FISCH) Two fission chambers for further monitoring of 2351500100031 the flux variation. 2351500100032 METHOD (ACTIV) Irradiation in 22 cm position, with foils and 2351500100033 under 1 mm Cd . 2351500100034 (COINC) 2351500100035 CORRECTION For background due to decay during irradiation - ~ 6.%.2351500100036 For fission products activity contribution 0.20+-0.1%. 2351500100037 Effects due to the sellotape were assumed to be 2351500100038 negligible. 2351500100039 For flux variation. 2351500100040 Correction term for Au - 0.027. 2351500100041 HISTORY (20190605C) M.M. 2351500100042 (20230517U) SD: Correction in Subent 002. 2351500100043 ENDBIB 41 0 2351500100044 NOCOMMON 0 0 2351500100045 ENDSUBENT 44 0 2351500199999 SUBENT 23515002 20230517 20231011 2351500200001 BIB 9 60 2351500200002 REACTION (92-U-238(N,G)92-U-239,,SIG) 2351500200003 REL-REF (A,12470003,S.P.Harris+,R,ANL-5032,1953) 2351500200004 2.71+-0.05 b . Mentioned as from ANL-LAT-109,1954 2351500200005 (A,21179005,P.A.Egelstaff,J,JNE,1,92,1954) 2351500200006 2.8+-0.10 b 2351500200007 (A,21181003,V.S.Crocker,J,JNE,1,234,1955) 2351500200008 2.72+-0.10 b (corrected for fission activity) 2351500200009 (A,21182003,V.G.Small,J,JNE,1,319,1955) 2351500200010 2.72+-0.06 b (revised assuming CS MnSO(4) 13.73 b) 2351500200011 (A,,S.J.Cocking+,R,NRDC-84,1955) Part 2. 2351500200012 2.69+-0.04 b 2351500200013 (A,,P.A.Egelstaff+,R,NRDC-84,1955) Part2. 2351500200014 2.69+-0.04 b 2351500200015 (A,12446002,H.Palevsky,C,55GENEVA,4,147,1955) 2351500200016 2.73+-0.07 2351500200017 Unpublished, Quoted in Proc.Geneva Conf. 2351500200018 (A,12444003,C.B.Bigham+,R,EANDC(CAN)-34,1968) 2351500200019 2.721+-0.016 b 2351500200020 SAMPLE U(3)O(8) powder, 0.005% U235 in the form of foils. 2351500200021 Two samples: 14680 mg/cm2 and 12435 mg/cm2 of U oxide 2351500200022 in 36 mg/cm2 and 26 mg/cm2 sellotape. 2351500200023 foil 1 foil2 2351500200024 Thermal factor Gth 0.9995 0.9996 2351500200025 Westcott function g 1.0023 1.0023 2351500200026 Cd ratio for ideal detector R 558 558 2351500200027 Epithermal flux fraction f 0.00482 0.00482 2351500200028 Renormalization correction C 1.230 1.230 2351500200029 Correction term W 0.000 0.000 2351500200030 Transmission factor for res. 2351500200031 neutrons through 1mm Cd , F 0.992 0.992 2351500200032 Cd ratio R 4.081+-0.10% 3.873+-0.62%2351500200033 ANALYSIS Weighted mean of six measurements. 2351500200034 DECAY-DATA (92-U-239,23.40MIN) 23.40+-0.05 min measured. 2351500200035 MONITOR (79-AU-197(N,G)79-AU-198,,SIG) 2351500200036 ERR-ANALYS (ERR-T) Total error (added linearly). 2351500200037 (ERR-S) Total random error(added in quadrature), 2351500200038 Sources of random error 2351500200039 flux determination - 0.25%, 2351500200040 activity/beta-detection-efficiency ratio - 0.56% 2351500200041 cadmium ratio - 0.16% . 2351500200042 (ERR-SYS) Total systematical - 0.59% (added in 2351500200043 quadrature). 2351500200044 Sources of systematical errors: 2351500200045 (ERR-1,,0.1) U-239 HL 2351500200046 (ERR-2) U-239 decay scheme 2351500200047 (ERR-3) Weight of U foils 2351500200048 (ERR-4) Thermal factor for U 2351500200049 (ERR-5) Sellotape flux depression 2351500200050 (ERR-6) Transmission factor F for U 2351500200051 (ERR-7) Fission correction 2351500200052 (ERR-8) Westcott factor g 2351500200053 (ERR-9,,0.1) Neptunium correction 2351500200054 (ERR-10) Au monitors cross section 2351500200055 (ERR-11) Thermal factor for Au 2351500200056 (ERR-12) Transmission factor F for Au 2351500200057 (ERR-13) Corrections for Au 2351500200058 STATUS (TABLE) Text of abstract, text on page 711, Table 1 of 2351500200059 J.of Nucl.Energy,v.23,p.705,1969 2351500200060 HISTORY (20230517U) SD: Value of ERR-T deleted from 2351500200061 COMMON section. 2351500200062 ENDBIB 60 0 2351500200063 COMMON 13 9 2351500200064 ERR-S ERR-SYS ERR-2 ERR-3 ERR-4 ERR-5 2351500200065 ERR-6 ERR-7 ERR-8 ERR-10 ERR-11 ERR-12 2351500200066 ERR-13 2351500200067 PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT 2351500200068 PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT 2351500200069 PER-CENT 2351500200070 0.63 0.59 0.3 0.2 0.1 0.22351500200071 0.1 0.1 0.1 0.3 0.1 0.12351500200072 0.1 2351500200073 ENDCOMMON 9 0 2351500200074 DATA 5 1 2351500200075 EN DATA ERR-T MONIT MONIT-ERR 2351500200076 EV B B B B 2351500200077 0.0253 2.69 0.03 98.8 0.3 2351500200078 ENDDATA 3 0 2351500200079 ENDSUBENT 78 0 2351500299999 ENDENTRY 2 0 2351599999999