ENTRY 31425 20100220 31443142500000001 SUBENT 31425001 20100220 31443142500100001 BIB 13 46 3142500100002 TITLE Measurement of the fission cross-section ratio for 3142500100003 Np-237/U-235 around 14 MeV neutron energies 3142500100004 AUTHOR (L.Desdin,S.Szegedi,J.Csikai) 3142500100005 INSTITUTE (3HUNKOS) 3142500100006 REFERENCE (J,AHP,65,(2-3),271,1989) 3142500100007 SAMPLE 481 Microgram U-235 and 418 microgram Np-237, as 3142500100008 tetrafluorides, were deposited onto Al holders. 3142500100009 The isotopic composition for uranium was (%): 3142500100010 ------------------------------------------------ 3142500100011 U-234 U-235 U-236 3142500100012 .0010 99.9955 .0035 3142500100013 and for neptunium: 3142500100014 ------------------------------------------------ 3142500100015 Np-237 Pu-239 Am-241 3142500100016 99.9917 .0078 .0005 3142500100017 FACILITY (CCW,3HUNKOS) 180 kV accelerator 3142500100018 INC-SOURCE (D-T) Fast neutrons were produced by 180 keV 3142500100019 deuterons. Neutron energy was selected by placing 3142500100020 the chamber at different directions with respect 3142500100021 to the deuteron beam. 3142500100022 METHOD (FISCT) 3142500100023 DETECTOR (IOCH) Low-mass, double ionization chamber, placed 3142500100024 at a distance of 7 cm from the beam spot on the 3142500100025 tritium target. The samples were placed back to back 3142500100026 in the chamber. At each neutron energy measurements 3142500100027 were done with two orientations: Np-237 sample facing 3142500100028 the neutron source and the same for the Np-237 3142500100029 sample as to average out the effects of geometry, 3142500100030 neutron scattering in the support plates between the 3142500100031 deposits and the momentum transfer. 3142500100032 CORRECTION Corrections have been made for fission fragment loss 3142500100033 in the samples (1.8%), for loss of the pulses under 3142500100034 the base line by extrapolation of the fragment 3142500100035 pulse-height spectrum to zero energy (2-4%) and for 3142500100036 thermal and epithermal neutrons (1%). 3142500100037 ERR-ANALYS (ERR-T) The error ( 4.3-4.4%) in the ratios of fission 3142500100038 cross-sections includes: 3142500100039 (ERR-S,0.6,0.8) the statistical error (.6-.8%), 3142500100040 (ERR-1,0.4,0.8) the error in the correction for loss 3142500100041 of pulses under the baseline (.4-.8%) 3142500100042 (ERR-2) the error in the correction for fission 3142500100043 fragment loss in sample deposits (.18%). 3142500100044 STATUS (TABLE) Data are taken from Table 3 in 3142500100045 Acta Physica Hung., vol. 65 (2-3), pp. 271-275 (1989). 3142500100046 HISTORY (19931123C) HW 3142500100047 (20090730A) SD:Updated to new date formats,lower case. 3142500100048 ENDBIB 46 0 3142500100049 COMMON 1 3 3142500100050 ERR-2 3142500100051 PER-CENT 3142500100052 0.18 3142500100053 ENDCOMMON 3 0 3142500100054 ENDSUBENT 53 0 3142500199999 SUBENT 31425002 20100220 31443142500200001 BIB 1 1 3142500200002 REACTION ((93-NP-237(N,F),,SIG)/(92-U-235(N,F),,SIG)) 3142500200003 ENDBIB 1 0 3142500200004 NOCOMMON 0 0 3142500200005 DATA 4 5 3142500200006 EN EN-ERR DATA ERR-T 3142500200007 MEV MEV NO-DIM NO-DIM 3142500200008 14.80 .17 .999 .043 3142500200009 14.70 .15 1.054 .046 3142500200010 14.45 .12 1.042 .045 3142500200011 14.12 .08 1.021 .044 3142500200012 13.75 .10 1.006 .043 3142500200013 ENDDATA 7 0 3142500200014 ENDSUBENT 13 0 3142500299999 ENDENTRY 2 0 3142599999999