ENTRY 22235 20121209 22342223500000001 SUBENT 22235001 20121209 22342223500100001 BIB 17 67 2223500100002 REFERENCE (J,ANE,19,(8),425,1992) 2223500100003 TITLE Measurement of the Th-232(n,2n)Th-231 reaction cross 2223500100004 section with 14.5 MeV neutrons 2223500100005 AUTHOR (H.Chatani,I.Kimura) 2223500100006 INSTITUTE (2JPNKTO) 2223500100007 FACILITY (CCW,2JPNKTO) Neutron generator at the Kyoto University2223500100008 critical assemblies, KUCA. 2223500100009 INC-SOURCE (D-T) The neutrons were produced by bombarding a 2223500100010 copper based Ti-T target with a 212 keV beam of 20 2223500100011 microAmps average beam current. 2223500100012 INC-SPECT .The average neutron energy was determined by the reac-2223500100013 tion ratio of Zr-90(n,2n) and Nb-93(n,2n), using 2 2223500100014 Zr and 2 Nb foils at a distance of 1.5 cm from the 2223500100015 Ti-T target. The reaction ratio for this position was 2223500100016 1.57 from which the corresponding average neutron 2223500100017 energy of 14.5+/-0.2 MeV was obtained. The flux 2223500100018 distribution and energy spectrum of the neutrons above2223500100019 6.5 MeV in the thorium samples were calculated with 2223500100020 the Monte Carlo code MCNP in which the source neutron 2223500100021 spectrum, which had been measured with a silicium 2223500100022 surface barrier detector was used as input. 2223500100023 METHOD (ACTIV,CHSEP) 2223500100024 DETECTOR (HPGE) The activities were measured with calibrated 2223500100025 small and large pure germanium detectors. Their re- 2223500100026 lative efficiencies for a 3x3 inc NaI scin are 10 and 2223500100027 30% respectively. The absolute Th-231 activity 2223500100028 was determined by comparison with the activity from 2223500100029 a 90% enriched uranium-aluminum alloy which 2223500100030 contains Th-231. 2223500100031 The time dependence of the neutron flux was monitored 2223500100032 using a moderator type neutron dose rate meter located2223500100033 about 2 m from the Ti-T target. 2223500100034 PART-DET (DG) 2223500100035 MONITOR (13-AL-27(N,A)11-NA-24-G,,SIG) The monitor cross sec- 2223500100036 tion was the evaluated value at 14.5 MeV in ENDF/B-VI 2223500100037 MONIT-REF (,,3,ENDF/B-VI,,1990) Data of ENDF/B-VI 2223500100038 SAMPLE .Three polyethylene packs of thorium nitrate powder of 2223500100039 about 500 mg weight were used. The thorium samples 2223500100040 were sandwiched with 0.5 mm thick aluminum foils for 2223500100041 neutron fluence monitoring. The distance between the 2223500100042 Ti-T target and the front surface of the samples was 2223500100043 1.6 cm. The samples were irradiated for about 7.5 hrs. 2223500100044 After irradiation the samples were chemically purified 2223500100045 CORRECTION .Corrections were applied for random, chance and sum- 2223500100046 ming coincidences. Corrections were also applied for 2223500100047 gamma self absorption and geometrical effects. 2223500100048 ERR-ANALYS (ERR-T) Total error, containing the following con- 2223500100049 tributions (percent). 2223500100050 neutron fluence monitor 2223500100051 (DATA-ERR1) counting statistics 0.2 2223500100052 (ERR-1) purity of Al foils 0.6 2223500100053 (ERR-2) efficiency of HPGE at 1.37 MeV 3.1 2223500100054 (ERR-3) flux distribution 3. 2223500100055 Th sample 2223500100056 (ERR-S) counting statistics 0.4 2223500100057 (ERR-4) recovery of Th 1. 2223500100058 (ERR-5) efficiency of HPGE at 84 keV 1.2 2223500100059 (ERR-6) self absorption 1.8 2223500100060 (DATA-ERR2) others 2. 2223500100061 total 5.4 2223500100062 STATUS (TABLE) .Data taken from Tbl.2 of ANE,19,(8),425 2223500100063 HISTORY (19930813C) N.O. 2223500100064 (19931129E) 2223500100065 (20121209A) SD: Updated to new date formats,lower case.2223500100066 Corrected according last EXFOR rules and Dict. 2223500100067 Page of ref. on ANE was corrected. ERR-ANALYS 2223500100068 was updated. COMMON was added. 2223500100069 ENDBIB 67 0 2223500100070 COMMON 9 6 2223500100071 ERR-1 ERR-2 ERR-3 DATA-ERR1 ERR-S ERR-4 2223500100072 ERR-5 ERR-6 DATA-ERR2 2223500100073 PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT 2223500100074 PER-CENT PER-CENT PER-CENT 2223500100075 0.6 3.1 3. 0.2 0.4 1. 2223500100076 1.2 1.8 2. 2223500100077 ENDCOMMON 6 0 2223500100078 ENDSUBENT 77 0 2223500199999 SUBENT 22235002 20121209 22342223500200001 BIB 2 2 2223500200002 REACTION (90-TH-232(N,2N)90-TH-231,,SIG) 2223500200003 DECAY-DATA (90-TH-231,25.52HR,DG,81./82./84.) 2223500200004 ENDBIB 2 0 2223500200005 NOCOMMON 0 0 2223500200006 DATA 5 1 2223500200007 EN EN-ERR DATA ERR-T MONIT 2223500200008 MEV MEV MB MB MB 2223500200009 1.4500E+01 2.0000E-01 1.1980E+03 6.5000E+01 1.1936E+02 2223500200010 ENDDATA 3 0 2223500200011 ENDSUBENT 10 0 2223500299999 ENDENTRY 2 0 2223599999999