ENTRY 40506 20190722 41894050600000001 SUBENT 40506001 20190722 41894050600100001 BIB 10 37 4050600100002 TITLE Measurement of the ratio of the 238U and 235U cross 4050600100003 sections for fission by 1-7-MeV neutrons 4050600100004 AUTHOR (B.I.Fursov, V.H.Kupriyanov, B.K.Maslennikov, 4050600100005 G.N.Smirenkin) 4050600100006 INSTITUTE (4RUSFEI) 4050600100007 REFERENCE (J,SJA,43,808,1977) 4050600100008 (J,AE,43,181,1977) Russian orig. of J,SJA,43,808,1977 4050600100009 ((C,77KIEV,3,144,1977)= 4050600100010 (R,INDC(CCP)-118,(3),144,1977)) Graphs only 4050600100011 FACILITY (VDG,4RUSFEI) 4050600100012 INC-SPECT (EN-RSL) Energy spread from neutron production target 4050600100013 thickness and angular spread 4050600100014 SAMPLE Layers of uranium oxides (~0.5 mg/cm2 thick) 4050600100015 deposited on Al backing (0.06 mm thick). 4050600100016 neutrons moderated from 180 and 500 keV, respectively.4050600100017 DETECTOR (FISCH) Two double fission ionization chambers filled 4050600100018 by Ar (90%) and CO2 (10%) at 760 mmHg. 4050600100019 CORRECTION Corrected for 4050600100020 - 235U in 238U layer 4050600100021 (main correction, 26% at 1 MeV,1.5-0.7% at 1.6-7 MeV4050600100022 - c.m. motion and angular anisotropy 4050600100023 (less than 2.5%) 4050600100024 - neutron flux difference in 235U and 238U layers. 4050600100025 Not corrected for 4050600100026 - neutron elastically scattered from electrode and 4050600100027 backing materials, 4050600100028 - neutrons scattered inelastically by detector walls, 4050600100029 electrode and backing materials. 4050600100030 HISTORY (19771226C) Compiled at the centre 4050600100031 (19881103U) One author name corrected (Kupriyanov), 4050600100032 DATA-ERR To ERR-T changed and obsolete keywords 4050600100033 modified. 4050600100034 (20060905A) M.M. Misprint in data was corrected. 4050600100035 (20110709A) M.M. Ref. J,SJA was added. 4050600100036 ERR-ANALYS was corrected according to now-days rules. 4050600100037 (20190724A) On. Major revision in 002. 003 . 4050600100038 (20200820A) M.M. Ref.INDC-CCP-118,3,144,1977 was added,4050600100039 ENDBIB 37 0 4050600100040 NOCOMMON 0 0 4050600100041 ENDSUBENT 40 0 4050600199999 SUBENT 40506002 20190722 41894050600200001 BIB 9 30 4050600200002 REACTION ((92-U-238(N,F),,SIG)/(92-U-235(N,F),,SIG)) 4050600200003 MONITOR ((92-U-238(N,F),,SIG)/(92-U-235(N,F),,SIG)) 4050600200004 MONIT-REF (40506003,B.I.Fursov+,J,SJA,43,808,1977) 4050600200005 This Entry, Subent 003. 4050600200006 INC-SOURCE (P-T) En=1-3 MeV 4050600200007 (D-D) En=3.6-7 MeV 4050600200008 ANALYSIS The shape ratios were normalized to the absolute 4050600200009 ratios at four calibration energies (1.476, 2.0, 2.5, 4050600200010 3.0 MeV). 4050600200011 FLAG (1.) Point normalized to the absolute shape 4050600200012 ERR-ANALYS (ERR-T) Total error 4050600200013 (ERR-1,0.54,3.20) Energy dependence (0.54-3.20%)4050600200014 - statistical error 4050600200015 (0.3-0.4%, but 2% at En<1.5 MeV, reduced by a 4050600200016 factor 1.4 by averaging results of two chambers.) 4050600200017 - fission of other isotopes 4050600200018 (maximum 3% at 1 MeV, decreases to ~0.1% at above 4050600200019 2 MeV). 4050600200020 - neutrons scattered by experimental room (0.1%) 4050600200021 - neutrons scattered by target material (0.2%) 4050600200022 - low energy neutrons (0.4% at 3 MeV, 2.8% at 7 MeV) 4050600200023 - Energy dependence of detection efficiency (0.3%) 4050600200024 - Inelastic scattering neutrons (0.3%) 4050600200025 (ERR-2) Absolute ratio (0.54%) 4050600200026 (ERR-3) Normalization procedure (0.1%) 4050600200027 (ERR-SYS) Systematic part of total error (0.55%) 4050600200028 STATUS (TABLE) Table 1 of Sov.J.Atom.Energy 43(1977)808 4050600200029 (DEP,40506003) Points used for normalization. 4050600200030 HISTORY (20190722A) On. Partial uncertainty coding updated. 4050600200031 EN-ERR/MeV -> EN-RSL/keV. 4050600200032 ENDBIB 30 0 4050600200033 COMMON 3 3 4050600200034 ERR-2 ERR-3 ERR-SYS 4050600200035 PER-CENT PER-CENT PER-CENT 4050600200036 0.1 0.54 0.55 4050600200037 ENDCOMMON 3 0 4050600200038 DATA 5 39 4050600200039 EN EN-RSL DATA ERR-T FLAG 4050600200040 MEV KEV NO-DIM PER-CENT NO-DIM 4050600200041 0.981 59. 0.0124 3.25 4050600200042 1.080 61. 0.0205 2.45 4050600200043 1.179 63. 0.0311 1.75 4050600200044 1.278 66. 0.0452 1.36 4050600200045 1.377 69. 0.113 1.40 4050600200046 1.476 72. 0.2281 0.61 1. 4050600200047 1.574 75. 0.304 0.80 4050600200048 1.672 78. 0.335 0.79 4050600200049 1.770 81. 0.368 0.80 4050600200050 1.870 84. 0.397 0.78 4050600200051 2.0 68. 0.4049 0.54 1. 4050600200052 2.1 70. 0.418 0.79 4050600200053 2.2 72. 0.427 0.79 4050600200054 2.3 73. 0.429 0.78 4050600200055 2.4 74. 0.432 0.78 4050600200056 2.5 75. 0.4304 0.51 1. 4050600200057 2.6 77. 0.433 0.78 4050600200058 2.7 78. 0.434 0.81 4050600200059 2.8 79. 0.436 0.77 4050600200060 2.9 82. 0.437 0.78 4050600200061 3.0 84. 0.4381 0.52 1. 4050600200062 3.6 192. 0.467 0.81 4050600200063 3.8 182. 0.472 0.81 4050600200064 4.0 146. 0.481 0.91 4050600200065 4.2 141. 0.495 0.84 4050600200066 4.4 132. 0.496 0.86 4050600200067 4.6 131. 0.504 0.89 4050600200068 4.8 125. 0.506 0.89 4050600200069 5.0 126. 0.510 0.76 4050600200070 5.2 129. 0.517 0.80 4050600200071 5.4 131. 0.525 0.86 4050600200072 5.6 135. 0.533 0.90 4050600200073 5.8 138. 0.545 1.08 4050600200074 6.0 142. 0.563 1.20 4050600200075 6.2 147. 0.581 1.35 4050600200076 6.4 152. 0.601 1.57 4050600200077 6.6 160. 0.611 1.85 4050600200078 6.8 167. 0.619 2.04 4050600200079 7.0 173. 0.640 2.19 4050600200080 ENDDATA 41 0 4050600200081 ENDSUBENT 80 0 4050600299999 SUBENT 40506003 20190722 41894050600300001 BIB 9 45 4050600300002 REACTION ((92-U-238(N,F),,SIG)/(92-U-235(N,F),,SIG)) 4050600300003 INC-SOURCE (P-LI7,P-T) 4050600300004 SAMPLE Enrichment: 4050600300005 235U: 99.9955+/-0.0010% (layer A) 4050600300006 238U: 99.5467% (layer B), 99.2705% (layer C, natural),4050600300007 98.7022% (layer D), 97.4876% (layer E). 4050600300008 The 238U/235U atom number ratios were determined by 4050600300009 four calibrations (B/A, C/A, D/A and E/A) by 4050600300010 irradiation of slow neutrons from Li(p,n) and T(p,n) 4050600300011 METHOD Threshold method for absolute measurement. 4050600300012 Measurements were performed twice with Li(p,n) and 4050600300013 T(p,n) sources at each of four calibration energies. 4050600300014 ANALYSIS Data are average of for runs (ratio U238/U235): 4050600300015 Layer Energies,MeV 4050600300016 1.476 2.0 2.5 3.0 4050600300017 B/A .2288+-.0030 .4043+-.0030 .4300+-.0050 .4375+-.00514050600300018 C/A .2264+-.0031 .4054+-.0056 .4320+-.0059 .4399+-.00584050600300019 D/A .2278+-.0024 .4088+-.0040 .4330+-.0038 .4405+-.00384050600300020 E/A .2300+-.0030 .4022+-.0040 .4277+-.0041 .4354+-.00434050600300021 CORRECTION Correction at En=2.5 MeV with calibration I 4050600300022 (layer B/layer A): 4050600300023 - Fission of other isotopes by fast neutrons (1.01%) 4050600300024 - Energy dependence of detection efficiency (1.48%) 4050600300025 - Neutron scatterred from target structure (2.10%) 4050600300026 - Neutron from associated p-n reactions (0.58%) 4050600300027 - Neutron scatterred from experimental room (0.28%) 4050600300028 - Neutron flux difference in U-235 and U-238 (1.61%) 4050600300029 ERR-ANALYS (ERR-T) Total error. 4050600300030 Structure at 2.5 MeV, for B/A layers: 4050600300031 - Statistics of measurement with fast neutrons (0.28%)4050600300032 - Energy dependence of detection efficiency (0.08%)4050600300033 - Neutron scatterred from target structure (0.16%)4050600300034 - Neutron from associated p-n reactions (0.14%)4050600300035 - Neutron scatterred from experimental room (0.10%)4050600300036 - Energy dependence of 238U(n,f)/235U(n,f) (0.56%)4050600300037 - Fraction of 235U nuclei in layer B of 238U (0.95%)4050600300038 - Statistics of measurement with slow neutrons (0.27%)4050600300039 - Neutron flux difference in U-235 and U-238 (0.22%)4050600300040 (ERR-1)Inelastic scattering (0.30%)4050600300041 (ERR-2)Energy dependence of detection efficiency(0.30%)4050600300042 STATUS (TABLE) Table 3 of Sov.J.Atom.Energy 43(1977)808 4050600300043 uncertainties - Table 4. 4050600300044 These points were used for normalization of Subent 002 4050600300045 data. 4050600300046 HISTORY (20190722C) On 4050600300047 ENDBIB 45 0 4050600300048 COMMON 2 3 4050600300049 ERR-1 ERR-2 4050600300050 PER-CENT PER-CENT 4050600300051 0.30 0.30 4050600300052 ENDCOMMON 3 0 4050600300053 DATA 3 4 4050600300054 EN DATA ERR-T 4050600300055 MEV NO-DIM NO-DIM 4050600300056 1.476 0.2282 0.0014 4050600300057 2.0 0.4050 0.0019 4050600300058 2.5 0.4306 0.0022 4050600300059 3.0 0.4384 0.0023 4050600300060 ENDDATA 6 0 4050600300061 ENDSUBENT 60 0 4050600399999 ENDENTRY 3 0 4050699999999