ENTRY 14220 20170307 14261422000000001 SUBENT 14220001 20170307 14261422000100001 BIB 12 46 1422000100002 TITLE Low-Flux Measurement of 235U Epicadmium 1422000100003 Capture-to-Fission Ratio 1422000100004 AUTHOR (W.C.Redman,M.M.Bretscher) 1422000100005 REFERENCE (J,NSE,31,247,1968) 1422000100006 (J,ANS,9,245,1966) Preliminary data. 1422000100007 REL-REF (I,,W.C.Redman+,J,NSE,27,34,1967) The equipment and 1422000100008 procedures reference. 1422000100009 INSTITUTE (1USAANL) 1422000100010 FACILITY (REAC,1USAANL) 1422000100011 INC-SPECT 1/E spectrum. 1422000100012 SAMPLE The copper and aluminum samples and the empty can 1422000100013 used to derive the net 235U and manganese 1422000100014 reactivities were unaltered. The same 252Cf source 1422000100015 was used. The amounts of uranium and manganese-copper 1422000100016 alloy were increased approximately fourfold, to 1422000100017 compensate partially for the reduced signal caused by 1422000100018 the absence of thermalneutron effects. These new 1422000100019 samples were all 12.7 x 2.5 cm, with These new 1422000100020 samples were all 12.7 x 2.5 cm, with thicknesses of 1422000100021 0.005 cm for the uranium and 0.015 cm for the 1422000100022 manganese - copper. The oscillated uranium sample 1422000100023 weighed 2.7247 g and the four uranium samples used 1422000100024 for the absolute fission-rate determination were all 1422000100025 within 1.2% of this mass. The four manganese - copper 1422000100026 samples which were first oscillated and subsequently 1422000100027 irradiated ranged from 3.4 to 4.2 g. 1422000100028 METHOD (MANGB) The experimental procedure requires the 1422000100029 measurement of 1) the relative reactivities rhoi of 1422000100030 samples of 235U, 252Cf, and manganese; 2) the 1422000100031 absolute capture rate for manganese RMn, and fission 1422000100032 rate for 235U, R25f; and 3) the spontaneous neutron 1422000100033 emission rate S for the 252Cf sample. The manganese 1422000100034 and 252Cf are used to establish the importance of 1422000100035 absorbed and fission neutrons, respectively. The only 1422000100036 additional information required is the number of 1422000100037 neutrons per 235U fission, nu25. When the results are 1422000100038 normalized to the same power level, the effective 1422000100039 capture-to-fission ratio: 1422000100040 alpha=(RMn/rhoMn)(rho25/R25f - (nu25*rhoCh/S))-1. 1422000100041 CORRECTION Experimental value 0.477 +- 0.022 1422000100042 Use of Mn and 252Cf as substitutes 0.492 +- 0.022 1422000100043 Effect of self shielding 0.500 +- 0.022 1422000100044 Deviation from 1/E spectrum 0.518 +- 0.023 1422000100045 Adjustment to 0.5-eV Cd cutoff 0.519 +- 0.023 1422000100046 DECAY-DATA (98-CF-252,2.646YR) 1422000100047 HISTORY (20170307C) BP 1422000100048 ENDBIB 46 0 1422000100049 NOCOMMON 0 0 1422000100050 ENDSUBENT 49 0 1422000199999 SUBENT 14220002 20170307 14261422000200001 BIB 3 6 1422000200002 REACTION (92-U-235(N,ABS),,ALF,,EPI) 1422000200003 ERR-ANALYS (DATA-ERR) The indicated standard errors reflect only 1422000200004 the reproducibility of the measurements and do not 1422000200005 allow for any additional uncertainty due to possible 1422000200006 systematic errors. 1422000200007 STATUS (TABLE) Table VI, page 253 of J,NSE,31,247,1968. 1422000200008 ENDBIB 6 0 1422000200009 NOCOMMON 0 0 1422000200010 DATA 3 1 1422000200011 EN-MIN DATA DATA-ERR 1422000200012 EV NO-DIM NO-DIM 1422000200013 0.5 0.519 0.023 1422000200014 ENDDATA 3 0 1422000200015 ENDSUBENT 14 0 1422000299999 ENDENTRY 2 0 1422099999999