ENTRY 21408 20211224 23062140800000001 SUBENT 21408001 20211224 23062140800100001 BIB 13 43 2140800100002 TITLE The ratio of thermal neutron capture to fission for 2140800100003 Pu-239 2140800100004 AUTHOR (M.J.Cabell,L.J.Slee) 2140800100005 INSTITUTE (2UK HAR) Chemistry division. 2140800100006 REFERENCE (J,JIN,25,607,1963) Data superseded. 2140800100007 (C,66PARIS,2,3,1966) Final data given. 2140800100008 (R,AERE-R-4173,1963) Addendum to JIN,25,607. 2140800100009 FACILITY (REAC,2UK HAR) PLUTO reactor. 2140800100010 INC-SOURCE (REAC) Irradiation in the flux scanning tube of the 2140800100011 B2 fuel element of the pluto reactor for 47 days. 2140800100012 INC-SPECT The neutron spectrum in pluto has a temperature of 2140800100013 106 degrees and a large epithermal component ranging 2140800100014 from 0.049 to 0.070 for the epithermal index. 2140800100015 SAMPLE Sample of three highly enriched plutonium isotopes, 2140800100016 Pu-239 (99.9%), Pu-240 (99.4%) and Pu-242 (98.1%) 2140800100017 were blended to give mixtures of known 2140800100018 isotopic composition. For irradiation the plutonium 2140800100019 mixtures were mixed with silica and evaporated to 2140800100020 dryness as nitrate. Afer irradiation plutonium was 2140800100021 chemically seperated then mass seperated. 2140800100022 METHOD (CHSEP,ASEP) Isotopic mass seperation using an A.E.I. 2140800100023 Type M.S.5 mass spectrometer. 0.1 ug plutonium 2140800100024 on tungsten filament surface ionisation source. 2140800100025 ANALYSIS Alpha derived from changes in isotopic composition 2140800100026 of plutonium mixtures from neutron capture 2140800100027 and fission. 2140800100028 MONITOR (27-CO-59(N,G)27-CO-60,,SIG) 2200 m/sec value. 2140800100029 Monitors were used to determine neutron flux, the 2140800100030 spectrum temperature and the epithermal component. 2140800100031 ERR-ANALYS (ERR-T) Total error 2140800100032 (ERR-1) Uncertainty from mass discrimination in 2140800100033 spectrometer (0.1%), 2140800100034 (ERR-2) Uncertainty in determination of spectrum 2140800100035 average alpha (1.4%), 2140800100036 (ERR-3) Uncertainty in neutron temperature (0.9 pc), 2140800100037 (ERR-4) Uncertainty in epi-thermal index (0.7%) 2140800100038 This is then combined with uncertainties in Westcotts 2140800100039 G and S factors to give a total absolute unceratainty 2140800100040 of 0.0070. 2140800100041 HISTORY (19800303C) 2140800100042 (20211224A) SD:Updated to new date formats,lower case. 2140800100043 Corrections in all Subents. SF4=Co-60-G+M -> Co-60; 2140800100044 SF6=SIG/SUM -> SIG in MONITOR. 2140800100045 ENDBIB 43 0 2140800100046 COMMON 5 3 2140800100047 MONIT ERR-1 ERR-2 ERR-3 ERR-4 2140800100048 B PER-CENT PER-CENT PER-CENT PER-CENT 2140800100049 37.2 0.1 1.4 0.9 0.7 2140800100050 ENDCOMMON 3 0 2140800100051 ENDSUBENT 50 0 2140800199999 SUBENT 21408002 20211224 23062140800200001 BIB 3 3 2140800200002 REACTION (94-PU-239(N,ABS),,ALF) 2200 m/sec value. 2140800200003 STATUS (TABLE) Text on p.13 of 66PARIS,Vol.2,p.3(1966) 2140800200004 HISTORY (20211224U) SD: STATUS updated. DATA-ERR -> ERR-T. 2140800200005 ENDBIB 3 0 2140800200006 NOCOMMON 0 0 2140800200007 DATA 3 1 2140800200008 EN DATA ERR-T 2140800200009 EV NO-DIM NO-DIM 2140800200010 2.530E-02 0.352 0.007 2140800200011 ENDDATA 3 0 2140800200012 ENDSUBENT 11 0 2140800299999 ENDENTRY 2 0 2140899999999