ENTRY 31517 20020215 00003151700000001 SUBENT 31517001 20020215 00003151700100001 BIB 17 58 3151700100002 INSTITUTE (3BZLIPE) 3151700100003 REFERENCE (J,RCA,83,117,1998) 3151700100004 AUTHOR (N.L.MAIDANA,M.S.DIAS,M.F.KOSKINAS) 3151700100005 TITLE Measurement of the thermal neutron capture cross 3151700100006 section of Cs-137 3151700100007 METHOD (ACTIV) Activation method. 30 min irradiation time. 3151700100008 Time interval between 3151700100009 the end of irradiation and counting is 10 min. 3151700100010 Nine irradiations have been performed in order to 3151700100011 obtain the needed statistics 3151700100012 FACILITY (REAC) IEA-R1 pool-type 2 MW IPEN research reactor 3151700100013 INC-SOURCE (REAC) Core of the reactor 3151700100014 INC-SPECT Flux of thermal neutrons 1.7E+12 n/cm*2/sec with 3151700100015 epithermal index in the Westcott r*sqrt(T/T0) 3151700100016 convention equals to 0.036. 3151700100017 DETECTOR (HPGE) calibrated using Co-60, Ba-133, Cs-137, Eu-152, 3151700100018 and Am-241 standard sources supplied by the IAEA. 3151700100019 Additional points were obtained using Na-22 and Y-88 3151700100020 standard sources. All samples were counted at distance3151700100021 of 88 mm from the detector. 3151700100022 SAMPLE 1.1 MBq Cs-137 target sealed inside a 0.8 mm thick 3151700100023 polyethylene sandwich and placed inside polyethylene 3151700100024 rabbit 3151700100025 MONITOR (79-AU-197(N,G)79-AU-198,,SIG) Au-Al alloy 3151700100026 with 0.1% gold in form of foils 3151700100027 were used to monitor the thermal and epithermal 3151700100028 neutron fluxes. Foils were irradiated in pairs with 3151700100029 and without 0.5 mm thick cadmium shield. 3151700100030 Compiler's note: used Au-197(n,g) standard cross sect. 3151700100031 is not given, but from other works done by the authors 3151700100032 at this time and with this method it is 98.8+-0.3 b 3151700100033 (see N.L.Maidana et al.,RCA,89,419,2001) 3151700100034 DECAY-MON (79-AU-198,2.6943D,DG,411.804,.9557) 3151700100035 DECAY-DATA (55-CS-137,1.102E+4D,DG,661.660,.851) 3151700100036 (55-CS-138,33.41MIN,DG,1435.86,.763) 3151700100037 (55-CS-138-M,2.91MIN,DG,1435.86,.19) 3151700100038 CORRECTION Corrected at dead time and pile-up were introduced 3151700100039 where they were needed. 3151700100040 Correction at branch of beta decay of Cs-138m 3151700100041 into Ba-138 without emission of 1435.86 keV gamma-rays,3151700100042 which depends from unknown isomer production 3151700100043 probability was estimated in the limits of 1.5% and 3151700100044 added to the overall uncertainty. 3151700100045 Correction at contribution of the epithermal neutrons 3151700100046 Has been estimated to be 5.7% 3151700100047 ERR-ANALYS (ERR-T) Full covariance analysis for 4 groups 3151700100048 of measurements was done. 3151700100049 The individual components of the uncertainty 3151700100050 100% correlated between groups of measurements: 3151700100051 production of Cs-138m - 1.5% 3151700100052 detector efficiency - 0.99% 3151700100053 decay correction of Cs-138 - 1.2 to 1.4% 3151700100054 dead time and pile-up - 0.97 3151700100055 epithermal neutrons (for 0.0253 eV cross section) -1.8%3151700100056 and with 0% correlations between groups is counting 3151700100057 statistics varying from 9.4 to 14.8%. 3151700100058 STATUS Data taken from p.118 of main reference. 3151700100059 HISTORY (20020214C) Compiled by VP 3151700100060 ENDBIB 58 0 3151700100061 NOCOMMON 0 0 3151700100062 ENDSUBENT 61 0 3151700199999 SUBENT 31517002 20020215 00003151700200001 BIB 1 3 3151700200002 REACTION (55-CS-137(N,G)55-CS-138,,SIG,,MXW) Effective cross 3151700200003 section for thermal spectrum with about 5.7% epithermal3151700200004 neutron contribution 3151700200005 ENDBIB 3 0 3151700200006 NOCOMMON 0 0 3151700200007 DATA 3 1 3151700200008 EN-DUMMY DATA ERR-T 3151700200009 EV B B 3151700200010 0.0253 0.264 0.015 3151700200011 ENDDATA 3 0 3151700200012 ENDSUBENT 11 0 3151700299999 SUBENT 31517003 20020215 00003151700300001 BIB 1 1 3151700300002 REACTION (55-CS-137(N,G)55-CS-138,,SIG) 2200 m/s cross section 3151700300003 ENDBIB 1 0 3151700300004 NOCOMMON 0 0 3151700300005 DATA 3 1 3151700300006 EN DATA ERR-T 3151700300007 EV B B 3151700300008 0.0253 0.253 0.015 3151700300009 ENDDATA 3 0 3151700300010 ENDSUBENT 9 0 3151700399999 ENDENTRY 3 0 3151799999999