ENTRY 14667 20201207 14761466700000001 SUBENT 14667001 20201207 14761466700100001 BIB 9 25 1466700100002 TITLE Fission Cross Sections of U235 and U238 for Fast 1466700100003 Neutrons 1466700100004 AUTHOR (N.P.Heydenburg,R.C.Meyer,K.Way) 1466700100005 REFERENCE (R,CF-636,1943) 1466700100006 INSTITUTE (1USACHI) 1466700100007 FACILITY (ACCEL,1USACHI) 1466700100008 DETECTOR (FISCH,IOCH) Two chambers were used. The second 1466700100009 chamber with a larger collector was used for enriched 1466700100010 uranium samples which were one inch in diameter. The 1466700100011 distance between the neutron source and the uranium 1466700100012 sample was increased for the absolute cross-section 1466700100013 determinations. The chambers were cadmium-lined as 1466700100014 shown. A boron-lined ionization chamber, surrounded 1466700100015 by paraffin, was used as a neutron monitor. 1466700100016 SAMPLE Samples of normal uranium of various thicknesses were 1466700100017 used for comparison with the enriched samples. The 1466700100018 235U content of the first two samples was checked by 1466700100019 comparing their UX2 beta ray yield with normal 1466700100020 uranium, after the UX2 content of the samples was in 1466700100021 equilibrium. 1466700100022 CORRECTION The correction for fission absorption was obtained 1466700100023 from an absorption curve, determined with the use of 1466700100024 a number of uniform U3O8 samples of known weight, 1466700100025 prepared by the Bureau of Standards. 1466700100026 HISTORY (20201207C) BP 1466700100027 ENDBIB 25 0 1466700100028 NOCOMMON 0 0 1466700100029 ENDSUBENT 28 0 1466700199999 SUBENT 14667002 20201207 14761466700200001 BIB 6 16 1466700200002 REACTION (92-U-238(N,F),,SIG,,SPA) 1466700200003 INC-SOURCE (D-C12) Cl2(d,n) neutrons of 640 keV maximum energy. 1466700200004 The carbon neutrons were produced by deuteron 1466700200005 bombardment of thick graphite discs. About 99 per 1466700200006 cent of these neutrons are due to the reaction 1466700200007 C12(d,n) for which Q = -.28 MeV. 1466700200008 SAMPLE The measurement was made with a normal U3O8 sample of 1466700200009 11 mm diameter and containing 1.140 mgm of U3O8. 1466700200010 METHOD For determining the absolute fission cross-section, 1466700200011 the distance between the uranium sample and the 1466700200012 graphite target was increased to 2.77 cm (distance to 1466700200013 top surface of graphite). The deuteron energy was 1466700200014 970 keV, giving neutrons of maximum energy 665 keV in 1466700200015 the forward direction. 1466700200016 ERR-ANALYS (DATA-ERR) No details on sources of uncertainties. 1466700200017 STATUS (TABLE) page 5. 1466700200018 ENDBIB 16 0 1466700200019 NOCOMMON 0 0 1466700200020 DATA 3 1 1466700200021 EN-MAX DATA DATA-ERR 1466700200022 KEV MB MB 1466700200023 640.0 18.6 1.1 1466700200024 ENDDATA 3 0 1466700200025 ENDSUBENT 24 0 1466700299999 SUBENT 14667003 20201207 14761466700300001 BIB 8 23 1466700300002 REACTION (92-U-235(N,F),,SIG,,SPA) 1466700300003 INC-SOURCE (D-C12) Cl2(d,n) neutrons of 640 keV maximum energy. 1466700300004 The carbon neutrons were produced by deuteron 1466700300005 bombardment of thick graphite discs. About 99 per 1466700300006 cent of these neutrons are due to the reaction 1466700300007 C12(d,n) for which Q = -.28 MeV. 1466700300008 SAMPLE The measurement was made with a normal U3O8 sample of 1466700300009 11 mm diameter and containing 1.140 mgm of U3O8. 1466700300010 METHOD For determining the absolute fission cross-section, 1466700300011 the distance between the uranium sample and the 1466700300012 graphite target was increased to 2.77 cm (distance to 1466700300013 top surface of graphite). The deuteron energy was 1466700300014 970 keV, giving neutrons of maximum energy 665 keV in 1466700300015 the forward direction. 1466700300016 ANALYSIS To obtain the cross section for U235 for C12 neutrons, 1466700300017 the natural value must be multiplied by 140 and by 1466700300018 .505 the fraction of fissions due C12 neutrons for 1466700300019 ordinary uranium. Dr. Way has made a more detailed 1466700300020 calculation of correction for the above data and 1466700300021 finds 235U cross section of 1.10 b. 1466700300022 ERR-ANALYS (DATA-ERR) No details on sources of uncertainties. 1466700300023 FLAG (1.) Corrected value. 1466700300024 STATUS (TABLE) page 5. 1466700300025 ENDBIB 23 0 1466700300026 NOCOMMON 0 0 1466700300027 DATA 4 2 1466700300028 EN-MAX DATA DATA-ERR FLAG 1466700300029 KEV B B NO-DIM 1466700300030 640.0 1.36 0.08 1466700300031 640.0 1.10 1. 1466700300032 ENDDATA 4 0 1466700300033 ENDSUBENT 32 0 1466700399999 SUBENT 14667004 20201207 14761466700400001 BIB 7 20 1466700400002 REACTION (92-U-235(N,F),,SIG,,SPA) 1466700400003 INC-SOURCE (D-C12) Cl2(d,n) neutrons of 640 keV maximum energy. 1466700400004 The carbon neutrons were produced by deuteron 1466700400005 bombardment of thick graphite discs. About 99 per 1466700400006 cent of these neutrons are due to the reaction 1466700400007 C12(d,n) for which Q = -.28 MeV. 1466700400008 SAMPLE Enriched sample Mg-XVII-B-1. This sample is 1466700400009 advantageous for getting sigma 235U because the 1466700400010 corrections for the fast neutrons from 13C and the 1466700400011 deuterium contamination will be small amounting to 1466700400012 only 5 per cent of the total number of fissions 1466700400013 observed. 1466700400014 ANALYSIS For a distance between sample and target of 5.35 cm, 1466700400015 8.7x10-3 fissions/mu were observed, using for the 1466700400016 neutron yield Q(15 degrees) = 15.2x10**6 neutrons/mu, 1466700400017 for a deuteron energy of 963 keV. Detailed 1466700400018 calculation by Dr. Way yields 1.20 b. 1466700400019 ERR-ANALYS (DATA-ERR) No details on sources of uncertainties. 1466700400020 FLAG (1.) Corrected value. 1466700400021 STATUS (TABLE) page 6. 1466700400022 ENDBIB 20 0 1466700400023 NOCOMMON 0 0 1466700400024 DATA 4 2 1466700400025 EN-MAX DATA DATA-ERR FLAG 1466700400026 KEV B B NO-DIM 1466700400027 640.0 1.52 0.07 1466700400028 640.0 1.20 1. 1466700400029 ENDDATA 4 0 1466700400030 ENDSUBENT 29 0 1466700499999 SUBENT 14667005 20201207 14761466700500001 BIB 5 12 1466700500002 REACTION (92-U-238(N,F),,SIG,,SPA) 1466700500003 INC-SOURCE (D-D) D(d,n) neutrons of maximum energy 3.95 MeV. 1466700500004 D3PO4 targets were used for most of this work. 1466700500005 SAMPLE All the data were taken with a U3O8 sample of weight 1466700500006 1.140 mg, diameter l1 mm. 1466700500007 METHOD Two absolute measurements have been made on the 1466700500008 fission cross-section for D-D neutrons in the forward 1466700500009 direction for normal uranium. From the value of the 1466700500010 observed fissions/mu, using the D3PO4 target and 1466700500011 applying the corrections the cross section was 1466700500012 extracted. 1466700500013 STATUS (TABLE) page 8. 1466700500014 ENDBIB 12 0 1466700500015 NOCOMMON 0 0 1466700500016 DATA 2 1 1466700500017 EN-MAX DATA 1466700500018 MEV B 1466700500019 3.95 0.69 1466700500020 ENDDATA 3 0 1466700500021 ENDSUBENT 20 0 1466700599999 SUBENT 14667006 20201207 14761466700600001 BIB 5 19 1466700600002 REACTION ((92-U-235(N,F),,SIG,,SPA)/(92-U-238(N,F),,SIG,,SPA)) 1466700600003 INC-SOURCE (D-D) D(d,n) neutrons of maximum energy 3.95 MeV. 1466700600004 D3PO4 targets were used for most of this work. 1466700600005 SAMPLE MgXVII-B-6, TX-22 sample. 1466700600006 METHOD The distance between the deuterium target and the 1466700600007 sample was 4.17 cm for the above measurements. A 1466700600008 number of additional 235 enriched and normal uranium 1466700600009 were received from Berkeley. These were used to 1466700600010 obtain more data on sigma 235U/sigma 238U for 3.95 1466700600011 MeV neutrons. A special chamber was constructed for 1466700600012 comparing two samples simultaneously. This was a 1466700600013 double ionization chamber with the two samples 1466700600014 mounted back to back on the high voltage plate. The 1466700600015 two samples were about 1 mm apart and measurements 1466700600016 were made with a distance of 5 cm between target and 1466700600017 sample. Bach chamber was connected to a separate 1466700600018 amplifier and counter. Comparisons were made on three 1466700600019 sets of samples for 3.95 MeV neutrons. 1466700600020 STATUS (TABLE) Table 4, page 7. 1466700600021 ENDBIB 19 0 1466700600022 NOCOMMON 0 0 1466700600023 DATA 2 1 1466700600024 EN-MAX DATA 1466700600025 MEV NO-DIM 1466700600026 3.95 2.54 1466700600027 ENDDATA 3 0 1466700600028 ENDSUBENT 27 0 1466700699999 SUBENT 14667007 20201207 14761466700700001 BIB 5 19 1466700700002 REACTION ((92-U-235(N,F),,SIG,,SPA)/(92-U-238(N,F),,SIG,,SPA)) 1466700700003 INC-SOURCE (D-D) D(d,n) neutrons of maximum energy 3.95 MeV. 1466700700004 D3PO4 targets were used for most of this work. 1466700700005 SAMPLE MgXVII-B-5, TX-18 sample. 1466700700006 METHOD The distance between the deuterium target and the 1466700700007 sample was 4.17 cm for the above measurements. A 1466700700008 number of additional 235 enriched and normal uranium 1466700700009 were received from Berkeley. These were used to 1466700700010 obtain more data on sigma 235U/sigma 238U for 3.95 1466700700011 MeV neutrons. A special chamber was constructed for 1466700700012 comparing two samples simultaneously. This was a 1466700700013 double ionization chamber with the two samples 1466700700014 mounted back to back on the high voltage plate. The 1466700700015 two samples were about 1 mm apart and measurements 1466700700016 were made with a distance of 5 cm between target and 1466700700017 sample. Bach chamber was connected to a separate 1466700700018 amplifier and counter. Comparisons were made on three 1466700700019 sets of samples for 3.95 MeV neutrons. 1466700700020 STATUS (TABLE) Table 4, page 7. 1466700700021 ENDBIB 19 0 1466700700022 NOCOMMON 0 0 1466700700023 DATA 2 1 1466700700024 EN-MAX DATA 1466700700025 MEV NO-DIM 1466700700026 3.95 2.36 1466700700027 ENDDATA 3 0 1466700700028 ENDSUBENT 27 0 1466700799999 SUBENT 14667008 20201207 14761466700800001 BIB 5 19 1466700800002 REACTION ((92-U-235(N,F),,SIG,,SPA)/(92-U-238(N,F),,SIG,,SPA)) 1466700800003 INC-SOURCE (D-D) D(d,n) neutrons of maximum energy 3.95 MeV. 1466700800004 D3PO4 targets were used for most of this work. 1466700800005 SAMPLE MgXVII-B-4, TX-18 sample. 1466700800006 METHOD The distance between the deuterium target and the 1466700800007 sample was 4.17 cm for the above measurements. A 1466700800008 number of additional 235 enriched and normal uranium 1466700800009 were received from Berkeley. These were used to 1466700800010 obtain more data on sigma 235U/sigma 238U for 3.95 1466700800011 MeV neutrons. A special chamber was constructed for 1466700800012 comparing two samples simultaneously. This was a 1466700800013 double ionization chamber with the two samples 1466700800014 mounted back to back on the high voltage plate. The 1466700800015 two samples were about 1 mm apart and measurements 1466700800016 were made with a distance of 5 cm between target and 1466700800017 sample. Bach chamber was connected to a separate 1466700800018 amplifier and counter. Comparisons were made on three 1466700800019 sets of samples for 3.95 MeV neutrons. 1466700800020 STATUS (TABLE) Table 4, page 7. 1466700800021 ENDBIB 19 0 1466700800022 NOCOMMON 0 0 1466700800023 DATA 2 1 1466700800024 EN-MAX DATA 1466700800025 MEV NO-DIM 1466700800026 3.95 2.21 1466700800027 ENDDATA 3 0 1466700800028 ENDSUBENT 27 0 1466700899999 SUBENT 14667009 20201207 14761466700900001 BIB 5 12 1466700900002 REACTION ((92-U-235(N,F),,SIG)/(92-U-238(N,F),,SIG)) 1466700900003 INC-SOURCE (D-D) D(d,n) neutrons of maximum energy 3.95 MeV. 1466700900004 Neutrons at 90 deg with energy 2.7 MeV. 1466700900005 D3PO4 targets were used for most of this work. 1466700900006 SAMPLE MgXVII-B-6, TX-22 sample. 1466700900007 METHOD Neutrons at 90 degrees, En=2.7 MeV, distance target 1466700900008 to sample 5 cm. A special chamber was constructed for 1466700900009 comparing two samples simultaneously. This was a 1466700900010 double ionization chamber with the two samples 1466700900011 mounted back to back on the high voltage plate. The 1466700900012 two samples were about 1 mm apart. 1466700900013 STATUS (TABLE) Table 4, page 7. 1466700900014 ENDBIB 12 0 1466700900015 NOCOMMON 0 0 1466700900016 DATA 2 1 1466700900017 EN DATA 1466700900018 MEV NO-DIM 1466700900019 2.7 2.98 1466700900020 ENDDATA 3 0 1466700900021 ENDSUBENT 20 0 1466700999999 SUBENT 14667010 20201207 14761466701000001 BIB 5 12 1466701000002 REACTION ((92-U-235(N,F),,SIG)/(92-U-238(N,F),,SIG)) 1466701000003 INC-SOURCE (D-D) D(d,n) neutrons of maximum energy 3.95 MeV. 1466701000004 Neutrons at 135 deg with energy 2.1 MeV. 1466701000005 D3PO4 targets were used for most of this work. 1466701000006 SAMPLE MgXVII-B-6, TX-22 sample. 1466701000007 METHOD Neutrons at 135 degrees, En=2.1 MeV, distance target 1466701000008 to sample 10 cm. A special chamber was constructed for 1466701000009 comparing two samples simultaneously. This was a 1466701000010 double ionization chamber with the two samples 1466701000011 mounted back to back on the high voltage plate. The 1466701000012 two samples were about 1 mm apart. 1466701000013 STATUS (TABLE) Table 4, page 7. 1466701000014 ENDBIB 12 0 1466701000015 NOCOMMON 0 0 1466701000016 DATA 2 1 1466701000017 EN DATA 1466701000018 MEV NO-DIM 1466701000019 2.1 2.95 1466701000020 ENDDATA 3 0 1466701000021 ENDSUBENT 20 0 1466701099999 ENDENTRY 10 0 1466799999999