ENTRY 10950 20170601 14321095000000001 SUBENT 10950001 20170601 14321095000100001 BIB 13 57 1095000100002 TITLE Absolute measurement of the uranium-235 fission cross 1095000100003 section from 0.2 to 1.2 MeV 1095000100004 AUTHOR (O.A.Wasson, M.M.Meier, K.C.Duval) 1095000100005 INSTITUTE (1USANBS) 1095000100006 REFERENCE (J,NSE,81,196,1982) 1095000100007 (C,79KNOX,,966,1979) 1095000100008 (W,WASSON,198112) 1095000100009 REL-REF (I,,W.P.Poenitz,J,NIM,109,413,1973) 1095000100010 Details of the neutron scintillator (black detector) 1095000100011 (O,10595001,O.A.Wasson,R,ANL-76-90,183,1976) 1095000100012 235U(n,f) cross sections from the same fission chamber1095000100013 FACILITY (VDG,1USANBS) NBS 3-MV Van de Graaff Laboratory 1095000100014 INC-SOURCE (P-LI7) Pulsed protons (1.8 to 3.0 MeV, 5 to 10 ns 1095000100015 wide at a 1-MHz repetition rate) on 7Li. 1095000100016 Neutrons were collimated to cone with half angle of 1095000100017 4.4 deg. 1095000100018 Source was heavily shielded with lithium carbonate 1095000100019 loaded paraffin. 1095000100020 DETECTOR (FISCH) Large-volume multiplated fission ionization 1095000100021 chamber 1095000100022 (SCIN) Large (12.5 cm diam x 19 cm long) NE110 plastic 1095000100023 scintillator ("Black detector") shielded with Pb, 1095000100024 paraffin and Li2CO3. 1095000100025 SAMPLE Plates of fission chamber coated with a nominal 1095000100026 thickness of 100 ug/cm2 uranium oxide on 10x18 cm 1095000100027 area. 1095000100028 Total mass of 235U was measured as 0.1709+/-0.0020 g. 1095000100029 METHOD (TOF) 235U desposit at ~1.3 m from the neutron source 1095000100030 and a neutron flux detector at ~5.9 m from the 1095000100031 neutron source. 1095000100032 CORRECTION Corrections made for 1095000100033 - air transmission, 1095000100034 - deadtime, 1095000100035 - backgrounds in fission chamber and flux monitor, 1095000100036 - collimator in-scattering, 1095000100037 - neutron transmission through edge of collimator, 1095000100038 - scatter from flux monitor shield, 1095000100039 - fission chamber spectrum loss, 1095000100040 - fission fragment absorption in deposits, 1095000100041 - variation of flux monitor efficiency with energy. 1095000100042 ERR-ANALYS (ERR-T) Total uncertainty 1095000100043 (ERR-S) Statistical uncertainty 1095000100044 (ERR-1) Air transmission 1095000100045 (ERR-2) Effective area of collimator 1095000100046 (ERR-3) Black detector spectral fitting and backgrounds1095000100047 (ERR-4) Fission chamber transmission and scattering 1095000100048 (ERR-5) Position of fission chamber (0.3%) 1095000100049 (ERR-6) Position of collimator (0.1%) 1095000100050 (ERR-7) Geometric area of collimator (0.5%) 1095000100051 (ERR-8) 235U mass in fission chamber (1.2%) 1095000100052 (ERR-9) Black detector efficiency calculation (1.0%) 1095000100053 (ERR-10) Fission spectrum extrapolation (0.4%) 1095000100054 (ERR-11) Black detector shield scattering (0.3%) 1095000100055 (ERR-12) Neutron beam non-uniformity (0.3%) 1095000100056 HISTORY (19820111C) 1095000100057 (19820812A) Updated reference 1095000100058 (20170601A) On. Major revision in 002. 1095000100059 ENDBIB 57 0 1095000100060 COMMON 9 6 1095000100061 EN-ERR ERR-5 ERR-6 ERR-7 ERR-8 ERR-9 1095000100062 ERR-10 ERR-11 ERR-12 1095000100063 KEV PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT 1095000100064 PER-CENT PER-CENT PER-CENT 1095000100065 10. 0.3 0.1 0.5 1.2 1.0 1095000100066 0.4 0.3 0.3 1095000100067 ENDCOMMON 6 0 1095000100068 ENDSUBENT 67 0 1095000199999 SUBENT 10950002 20170601 14321095000200001 BIB 4 8 1095000200002 REACTION (92-U-235(N,F),,SIG,,AV) 1095000200003 FLAG (1.) Aluminum collimator used 1095000200004 (2.) Brass collimator used 1095000200005 STATUS Values except for energy dependent systematic 1095000200006 uncertainties are coincide with those in Table II of 1095000200007 Nucl.Sci.Eng.81(1982)196. 1095000200008 (APRVD) Approved by O.A.Wasson, 1982/2/23 1095000200009 HISTORY (20170601A) On. ERR-S: 1.6% -> 1.5% at 236 to 285 keV. 1095000200010 ENDBIB 8 0 1095000200011 NOCOMMON 0 0 1095000200012 DATA 10 37 1095000200013 EN-MIN EN-MAX DATA ERR-T ERR-S ERR-1 1095000200014 ERR-2 ERR-3 ERR-4 FLAG 1095000200015 KEV KEV B PER-CENT PER-CENT PER-CENT 1095000200016 PER-CENT PER-CENT PER-CENT NO-DIM 1095000200017 217. 272. 1.285 2.7 1.6 0.7 1095000200018 0.3 1.0 0.2 1. 1095000200019 236. 285. 1.241 2.7 1.5 0.7 1095000200020 0.4 1.0 0.2 1. 1095000200021 265. 313. 1.281 3.6 1.7 0.7 1095000200022 0.3 2.4 0.3 2. 1095000200023 290. 333. 1.202 2.6 1.5 0.7 1095000200024 0.2 0.9 0.3 1. 1095000200025 325. 368. 1.210 2.5 1.4 0.7 1095000200026 0.3 0.6 0.2 1. 1095000200027 352. 403. 1.252 2.4 1.2 0.4 1095000200028 0.2 0.8 0.2 2. 1095000200029 369. 406. 1.209 2.4 1.3 0.7 1095000200030 0.2 0.5 0.2 1. 1095000200031 401. 428. 1.212 2.4 1.2 1.0 1095000200032 0.2 0.4 0.2 1. 1095000200033 451. 488. 1.123 2.4 1.1 1.0 1095000200034 0.2 0.4 0.2 1. 1095000200035 456. 497. 1.148 2.3 1.0 0.5 1095000200036 0.2 0.7 0.2 2. 1095000200037 482. 531. 1.107 2.2 1.1 0.7 1095000200038 0.2 0.4 0.2 1. 1095000200039 492. 556. 1.139 2.2 0.9 0.6 1095000200040 0.2 0.7 0.2 2. 1095000200041 520. 567. 1.127 2.1 0.9 0.6 1095000200042 0.2 0.4 0.2 1. 1095000200043 545. 595. 1.115 2.3 1.0 0.6 1095000200044 0.2 0.7 0.2 2. 1095000200045 563. 612. 1.094 2.1 0.9 0.5 1095000200046 0.2 0.4 0.2 1. 1095000200047 600. 650. 1.111 2.2 0.8 0.5 1095000200048 0.3 0.9 0.2 2. 1095000200049 600. 652. 1.121 2.2 1.0 0.5 1095000200050 0.3 0.4 0.2 1. 1095000200051 649. 696. 1.097 2.2 1.0 0.5 1095000200052 0.3 0.4 0.2 1. 1095000200053 667. 729. 1.115 2.3 1.1 0.5 1095000200054 0.3 0.7 0.2 2. 1095000200055 686. 738. 1.100 2.2 1.0 0.5 1095000200056 0.2 0.4 0.2 1. 1095000200057 726. 778. 1.125 2.2 1.0 0.5 1095000200058 0.2 0.4 0.2 1. 1095000200059 757. 818. 1.120 2.2 1.0 0.4 1095000200060 0.2 0.5 0.2 1. 1095000200061 787. 821. 1.097 2.3 1.1 0.4 1095000200062 0.2 0.7 0.2 2. 1095000200063 802. 860. 1.139 2.2 1.0 0.4 1095000200064 0.2 0.5 0.2 1. 1095000200065 835. 875. 1.111 2.2 0.9 0.4 1095000200066 0.2 0.7 0.2 2. 1095000200067 840. 898. 1.103 2.2 1.0 0.4 1095000200068 0.2 0.5 0.2 1. 1095000200069 876. 939. 1.135 2.2 1.0 0.4 1095000200070 0.2 0.6 0.3 1. 1095000200071 905. 955. 1.179 2.3 1.1 0.5 1095000200072 0.2 0.7 0.3 2. 1095000200073 905. 990. 1.170 2.3 1.1 0.5 1095000200074 0.2 0.6 0.3 1. 1095000200075 972. 1016. 1.200 2.3 0.9 1.0 1095000200076 0.2 0.6 0.2 1. 1095000200077 1010. 1060. 1.200 2.3 1.0 0.6 1095000200078 0.2 0.7 0.2 2. 1095000200079 1030. 1070. 1.205 2.2 0.9 0.5 1095000200080 0.2 0.7 0.2 1. 1095000200081 1070. 1120. 1.175 2.3 1.0 0.9 1095000200082 0.2 0.6 0.2 2. 1095000200083 1079. 1120. 1.200 2.3 1.0 0.6 1095000200084 0.2 0.7 0.2 1. 1095000200085 1127. 1170. 1.180 2.3 1.0 0.7 1095000200086 0.2 0.7 0.2 1. 1095000200087 1136. 1191. 1.193 2.3 1.1 0.7 1095000200088 0.2 0.6 0.2 2. 1095000200089 1174. 1218. 1.179 2.3 1.2 0.6 1095000200090 0.2 0.7 0.2 1. 1095000200091 ENDDATA 78 0 1095000200092 ENDSUBENT 91 0 1095000299999 ENDENTRY 2 0 1095099999999