ENTRY 30781 20220202 32073078100000001 SUBENT 30781001 20220202 32073078100100001 BIB 19 92 3078100100002 TITLE Neutron capture cross section measurement of 232Th in 3078100100003 the energy range of 400-950 keV 3078100100004 AUTHOR (R.P.Anand, H.M.Jain, S.Kailas, S.K.Gupta, 3078100100005 V.S.Ramamurthy) 3078100100006 INSTITUTE (3INDTRM) 3078100100007 REFERENCE (J,ANE,16,87,1989) 3078100100008 ((J,RE,93,189,1986)=(C,85SANTA,1,525,1985)) 3078100100009 Prelim. of the ANE article 3078100100010 FACILITY (VDG,3INDTRM) 5.5 MeV accelerator 3078100100011 SAMPLE - The Th-oxide target in form of discs (~14 mm diam., 3078100100012 2 mm thick). 3078100100013 - Two thin Au foils (0.013 mm thick, ~14 mm diam.) 3078100100014 INC-SOURCE (P-LI7) 3078100100015 DETECTOR (GELI) 100 cm3 3078100100016 METHOD (ACTIV) 3078100100017 - Activation method was employed in which the gammas 3078100100018 emitted from the decay of the Th-233 were measured. 3078100100019 - The cross sections were measured relative to the 3078100100020 neutron capture cross sections of Au-197. 3078100100021 ANALYSIS The photopeak area of 459 keV g-ray was extracted with 3078100100022 the computer code SAMPO, which fits each gamma-ray 3078100100023 with Gaussian + two exponentials. 3078100100024 The fitting parameters for the code were determined by 3078100100025 using standard monoenerg. gamma-sources. 3078100100026 MONITOR ((MONIT1)(90-TH-232(N,G)90-TH-233,,SIG,,MXW)/ 3078100100027 (79-AU-197(N,G)79-AU-198,,SIG,,MXW)) 3078100100028 The ratio of the capture cross section of Th and Au at 3078100100029 thermal neutron energy was used as monitor. 3078100100030 The values of the thermal neutron capture cross section3078100100031 used were: 7.40 +/- 0.08 barn for Th-232 3078100100032 98.8 +/- 0.3 barn for Au-197 3078100100033 ((MONIT2)79-AU-197(N,G)79-AU-198,,SIG) 3078100100034 MONIT-REF ((MONIT1),,R,BNL-325,(1),1973) 3078100100035 ((MONIT2),,R,IAEA-227,1983) 3078100100036 The capture cross sections of 197-Au in the keV 3078100100037 energy range were taken from standard cross sections 3078100100038 recommended by IAEA. 3078100100039 DECAY-DATA (90-TH-233,22.3MIN,DG,459.) 3078100100040 DECAY-MON (79-AU-198-G,2.7D,DG,412.) 3078100100041 CORRECTION Measured cross sections were corrected for: 3078100100042 1. Multiple scattering and self-shielding effects: 3078100100043 --------------------------------------------------- 3078100100044 En (keV) C1 C2 3078100100045 --------------------------------------------------- 3078100100046 Thermal maxw 0.97230 1.0562 3078100100047 425 0.99995 1.0295 3078100100048 480 0.99995 1.0305 3078100100049 535 0.99995 1.0310 3078100100050 590 0.99995 1.0313 3078100100051 615 0.99995 1.0316 3078100100052 645 0.99996 1.0319 3078100100053 690 0.99996 1.0321 3078100100054 740 0.99996 1.0325 3078100100055 845 0.99996 1.0333 3078100100056 950 0.99997 1.0338 3078100100057 ------------ -------------------------------------- 3078100100058 C1: Self-shielding + multiple scattering correction 3078100100059 factor for Al-foils 3078100100060 C2: Multiple scattering correction factor for Th- 3078100100061 pellet 3078100100062 2. The effect of the variation of neutron flux as a 3078100100063 function of time was taken into consideration. 3078100100064 This correction factor was found to be less than 6%.3078100100065 3. Second group of neutrons due Ep > 2.4 MeV the 3078100100066 estimated error due to this corr < +/- 1%. 3078100100067 4. The average energy and the spread of the neutron 3078100100068 beam for Li target thickness. The neutron spread 3078100100069 due this was calcu. to be varying from +/-15 to 3078100100070 +/- 25 keV 3078100100071 5. The energy spread due to the angular spread of 3078100100072 neutrons. This was estimated to be about +/- 17 keV.3078100100073 ERR-ANALYS (ERR-T) Overall uncertainty was estimated (5-6%) 3078100100074 (ERR-S,1.,4.) The statistical and fitting error in the 3078100100075 determining the photopeak areas of the 459 and 412 keV3078100100076 gammas by SAMPO: (2-4%) for keV 3078100100077 (<1%)for thermal 3078100100078 (ERR-1,,2.) The uncertainty due the self-shielding and 3078100100079 multiple scattering (<2%) 3078100100080 (ERR-2,,1.) The uncertainty on the thermal capture 3078100100081 cross sections of 232-Th and 197-Au: (<1%) 3078100100082 CRITIQUE The present measurements are in good agreement with the3078100100083 other recent measurements and deviations are within 3078100100084 experimental errors up to En=740keV. 3078100100085 STATUS (TABLE) Table 2 of Ann. Nucl. Energy, 16 (1989) 87 3078100100086 HISTORY (19880411C) TMK 3078100100087 (19890412A) VOF.-Complete revision. 3078100100088 (20090725A) SD: Updated to new date formats,lower case.3078100100089 Units and data in COMMON section were corrected, 3078100100090 energy was added. Cosmetic changes and codes for 3078100100091 partial uncertainties were added. 3078100100092 (20120703U) On. ANALYSIS: Code AREA deleted 3078100100093 (20220202A) VT ERR-ANALYS: corrected 3078100100094 ENDBIB 92 0 3078100100095 COMMON 2 3 3078100100096 EN-NRM MONIT1 3078100100097 EV NO-DIM 3078100100098 0.0253 0.0749 3078100100099 ENDCOMMON 3 0 3078100100100 ENDSUBENT 99 0 3078100199999 SUBENT 30781002 20220202 32073078100200001 BIB 1 1 3078100200002 REACTION (90-TH-232(N,G)90-TH-233,,SIG) 3078100200003 ENDBIB 1 0 3078100200004 NOCOMMON 0 0 3078100200005 DATA 5 10 3078100200006 EN EN-RSL DATA ERR-T MONIT2 3078100200007 KEV KEV MB MB MB 3078100200008 425. 35. 150. 8. 151.4 3078100200009 480. 35. 151. 8. 138. 3078100200010 535. 35. 166. 9. 127. 3078100200011 590. 35. 160. 9. 118. 3078100200012 615. 45. 150. 8. 115. 3078100200013 645. 35. 167. 9. 108.8 3078100200014 690. 45. 164. 9. 102.4 3078100200015 740. 45. 170. 9. 96.4 3078100200016 845. 45. 175. 9. 87.6 3078100200017 950. 45. 162. 9. 84.2 3078100200018 ENDDATA 12 0 3078100200019 ENDSUBENT 18 0 3078100299999 ENDENTRY 2 0 3078199999999