ENTRY 10971 20210917 14861097100000001 SUBENT 10971001 20210917 14861097100100001 BIB 14 63 1097100100002 TITLE Measurement of the 235U neutron-induced fission cross 1097100100003 section at 14.1 MeV 1097100100004 AUTHOR (O.A.Wasson, A.D.Carlson, K.C.Duvall) 1097100100005 INSTITUTE (1USANBS) 1097100100006 REFERENCE (J,NSE,80,282,1982) 1097100100007 (W,WASSON,198105) 1097100100008 FACILITY (VDG,1USANBS) 3-MV positive-ion Van de Graaff 1097100100009 INC-SOURCE (D-T) ~250 keV deuteron beam on TiT (2.8 mg/cm2 thick) 1097100100010 INC-SPECT Neutron beam energy, energy distribution 1097100100011 and energy uncertainty were deduced from the reaction 1097100100012 kinematics, deuteron beam energy loss in target, and 1097100100013 measured spatial shape of neutron beam. 1097100100014 (EN-RSL-FW) Energy spread (FWHM) 1097100100015 DETECTOR (FISCH) Parallel plate ionization chamber with 2pi 1097100100016 geometry. Two sample deposits placed back-to-back. 1097100100017 (SIBAR) Totally depleted surface barrier detector for 1097100100018 associated alphas detection at 84 deg. 1097100100019 (SCIN) NE-110 plastic scintillator (2.5 cm diam., 8 cm 1097100100020 thick) operated in coincidence with alpha detector to 1097100100021 measure the angular shape of the neutron beam. 1097100100022 SAMPLE Two 8 mm radius deposits of UO2 (1042 ug/cm2) 1097100100023 evaporated onto Ti backing (0.0063 mm thick). 1097100100024 Extensive measurements of areal density made using 1097100100025 thermal neutron induced fission counting and 235U 1097100100026 reference deposit. 1097100100027 (92-U-235,ENR=0.99830) 1097100100028 (92-U-234,ENR=0.00062) 1097100100029 (92-U-236,ENR=0.00037) 1097100100030 (92-U-238,ENR=0.00069) 1097100100031 METHOD (ASSOP) Time correlated associated particle method. 1097100100032 Background due to scattered neutrons eliminated by 1097100100033 coincidence requirement between fission event and 1097100100034 alpha detector. 1097100100035 CORRECTION Corrected for 1097100100036 - variation in uranium deposit thickness, 1097100100037 - uncertainty in neutron beam profile, 1097100100038 - fission events below discrimination level, 1097100100039 - fission fragments absorbed in deposits, 1097100100040 - fission by other than 235U, 1097100100041 - neutron attenuation, 1097100100042 - accidental coincident background contributions. 1097100100043 ERR-ANALYS (ERR-T) Total uncertainty (1.5%) propagated from 1097100100044 (ERR-S) Ratio of net alpha-fission coincidence yield 1097100100045 to alpha yield (0.9%)1097100100046 (ERR-1) Neutrons scattered from beam (0.3%)1097100100047 (ERR-2) Fission fragment absorption (0.8%)1097100100048 (ERR-3) Fission spectrum loss (0.3%)1097100100049 (ERR-4) Neutron beam shape and deposit uniformity(0.3%)1097100100050 (ERR-5) Standard 235U reference mass (0.1%)1097100100051 (ERR-6) Standard 235U reference areal density (0.2%)1097100100052 (ERR-7) Thermal neutron scattering from Pt backing 1097100100053 of reference deposit (0.4%)1097100100054 (ERR-8) 235U areal density uncertainty (0.3%)1097100100055 (EN-ERR) Estimated 1 standard deviation uncertainty 1097100100056 STATUS (TABLE) Tables XII+XIII of Nucl.Sci.Eng.80(1982)282 1097100100057 except for the incident energy uncertainty and 1097100100058 resolution, which are taken from a letter from 1097100100059 O.Wasson (1981-09-11) 1097100100060 (APRVD) Approved by O.A.Wasson (1981-09-15) 1097100100061 HISTORY (19810721C) 1097100100062 (19820917A) REFERENCE, TITLE updated. 1097100100063 (20170721A) On. ERR-ANALYS updated. Major rev. in 002. 1097100100064 (20210917U) On. INC-SPECT corrected. 1097100100065 ENDBIB 63 0 1097100100066 NOCOMMON 0 0 1097100100067 ENDSUBENT 66 0 1097100199999 SUBENT 10971002 20210917 14861097100200001 BIB 2 4 1097100200002 REACTION (92-U-235(N,F),,SIG) 1097100200003 HISTORY (20170721A) On. EN-RSL -> EN-RSL-FW. %-uncertainty 1097100200004 adopted for ERR-T. 1097100200005 (20210917U) On. HISTORY corrected (HW -> FW) 1097100200006 ENDBIB 4 0 1097100200007 COMMON 8 6 1097100200008 ERR-1 ERR-2 ERR-3 ERR-4 ERR-5 ERR-6 1097100200009 ERR-7 ERR-8 1097100200010 PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT 1097100200011 PER-CENT PER-CENT 1097100200012 0.3 0.8 0.3 0.3 0.1 0.2 1097100200013 0.4 0.3 1097100200014 ENDCOMMON 6 0 1097100200015 DATA 6 1 1097100200016 EN EN-ERR EN-RSL-FW DATA ERR-T ERR-S 1097100200017 MEV MEV MEV B PER-CENT PER-CENT 1097100200018 14.1 0.05 0.10 2.080 1.5 0.9 1097100200019 ENDDATA 3 0 1097100200020 ENDSUBENT 19 0 1097100299999 ENDENTRY 2 0 1097199999999