ENTRY 31510 20010213 00003151000000001 SUBENT 31510001 20010213 00003151000100001 BIB 16 63 3151000100002 INSTITUTE (3ARGCAB) 3151000100003 REFERENCE (J,NSE,127,245,199711) Final publication 3151000100004 AUTHOR (P.M.SUAREZ,M.A.ARRIBERE,S.RIBIERO GUEVARA, 3151000100005 A.J.KESTELMAN) 3151000100006 TITLE Experimental and Calculated Scandium Threshold 3151000100007 Reaction Cross Sections Averaged over a U-235 Fission 3151000100008 Neutron Specrum 3151000100009 METHOD (ACTIV) Activation method with registration of 3151000100010 secondary gamma-ray spectra. 3151000100011 FACILITY (REAC) 3151000100012 INC-SOURCE (REAC) Thermal neutron flux from RA-6 materials test 3151000100013 reactor at Centre Atomico Barilochi 3151000100014 INC-SPECT Undisturbed U-235 fission spectrum. Set of 8 3151000100015 activation detectors having thresholds from 2.6 to 3151000100016 11.6 MeV were used to show that flux of fission 3151000100017 neutrons is undisturbed 3151000100018 DETECTOR (HPGE) 67 cm*3 ORTEC high-purity germanium intrinsic-N 3151000100019 coaxial detector with resolution 2 keV at 1.33 MeV. 3151000100020 The detector absolute efficiency curve was obtained 3151000100021 with IAEA standard sources (Am-241, Ba-133, Co-60, 3151000100022 Cs-137, Eu-152) calibrated within 2 per-cent 3151000100023 uncertainty. Ra-226 source was also used 3151000100024 SAMPLE 3 scandium foils, 0.127 mm thick and 99.85 per-cent 3151000100025 pure with a mass from 4 to 18 mg inside 1 mm thick 3151000100026 cadmium cover. 1.5 mg/g impurities include gold, 3151000100027 manganese, terbium, tantalum (1.2 mg/g), samarium, 3151000100028 sodium, and tungsten. 3151000100029 MONITOR (28-NI-58(N,P)27-CO-58,,SIG,,FIS) Data are taken 3151000100030 from J.H. Baard, W.L. Zijp and H. Nolthenius, Nuclear 3151000100031 Data Guide for Reactor Neutron Metrology, Kluwer 3151000100032 Academic Publishers, Dordrecht, The Netherlands, 1989 3151000100033 DECAY-MON (27-CO-58-G,70.82D,DG,810.772,.9944) Data are taken 3151000100034 from J.H. Baard, W.L. Zijp and H. Nolthenius, Nuclear 3151000100035 Data Guide for Reactor Neutron Metrology, Kluwer 3151000100036 Academic Publishers, Dordrecht, The Netherlands, 1989 3151000100037 CORRECTION Gamma self-attenuation factor for 811.79 keV line in 3151000100038 nickel foil and wire was calculated as 0.992 3151000100039 and 0.981, respectively. Gamma self-attenuation 3151000100040 factors for scandium foil are given in free text 3151000100041 under DECAY-DATA 3151000100042 ERR-ANALYS The systematic uncertainty components for all 3151000100043 measurements: 2.8% - uncertainty of the reference 3151000100044 cross section value, 2 to 3% - uncertainty in the 3151000100045 detector absolute efficiency determination (depending 3151000100046 on energy and counting geometry), 1% - uncertainty due 3151000100047 to sample impurities, 1% - uncertainty in sample and 3151000100048 monitor foils mass determination, nickel isotopic 3151000100049 abundance, decay constant, self-attenuation 3151000100050 corrections. Total systematic uncertainty is between 3151000100051 4.3 and 4.8% 3151000100052 COMMENT The experimental results were compared with the 3151000100053 calculated ones. The calculated averaged cross 3151000100054 sections were obtained by folding the statistical 3151000100055 model curves adjusted by list square procedure to the 3151000100056 experimental microscopic cross sections with 9 3151000100057 different analytical model presentations. It is shown 3151000100058 that for Sc-45(n,2n) high threshold reaction the 3151000100059 calculated values are systematically lower than 3151000100060 experimental values especially for Watt 3151000100061 parameterisation. New analytical presentation for U-2353151000100062 fission neutron spectra which gives more neutrons for 3151000100063 En > 10 MeV is proposed 3151000100064 HISTORY (20010213C) Compiled by VP 3151000100065 ENDBIB 63 0 3151000100066 COMMON 3 3 3151000100067 EN-DUMMY MONIT MONIT-ERR 3151000100068 MEV MB MB 3151000100069 1.5 111. 3. 3151000100070 ENDCOMMON 3 0 3151000100071 ENDSUBENT 70 0 3151000199999 SUBENT 31510002 20010213 00003151000200001 BIB 4 15 3151000200002 REACTION (21-SC-45(N,A)19-K-42,,SIG,,FIS) 3151000200003 ANALYSIS Final value is obtained as weighted averaged 3151000200004 of results of 3 measurements with their statistical 3151000200005 uncertainties (0.289+-0.010, 0.3089+-0.0059 and 3151000200006 0.3131+-0.0062 mb). Then systematic uncertainty was 3151000200007 added 3151000200008 DECAY-DATA (19-K-42,12.360HR,DG,1524.70,.1808) Scandium foil 3151000200009 self-attenuation factor is 0.999. Possible 3151000200010 interference due to potassium impurity in the scandium 3151000200011 sample through 19-K-41(n,g)19-K-42 reaction was 3151000200012 assumed less than 1% 3151000200013 ERR-ANALYS Total uncertainty is given. Main contribution to the 3151000200014 uncertainty (4 to 5%)is due to background in 3151000200015 gamma-spectrum generated by the 2010 keV sum peak 3151000200016 (889+1121) from the decay of Sc-46 3151000200017 ENDBIB 15 0 3151000200018 NOCOMMON 0 0 3151000200019 DATA 2 1 3151000200020 DATA ERR-T 3151000200021 MB MB 3151000200022 0.308 0.016 3151000200023 ENDDATA 3 0 3151000200024 ENDSUBENT 23 0 3151000299999 SUBENT 31510003 20010213 00003151000300001 BIB 5 24 3151000300002 REACTION (21-SC-45(N,2N)21-SC-44-G,,SIG,,FIS) 3151000300003 DECAY-DATA (21-SC-44-G,3.927HR,DG,1157.031,0.9990) Scandium foil 3151000300004 self-attenuation factor is 0.998 3151000300005 (21-SC-44-M,58.6HR,DG,271.13,0.867) Scandium foil 3151000300006 self-attenuation factor is 0.992 3151000300007 (21-SC-44-M,58.6HR,DG,1001.85,0.0120) Scandium foil 3151000300008 self-attenuation factor is 0.998 3151000300009 (21-SC-44-M,58.6HR,DG,1126.08,0.012) Scandium foil 3151000300010 self-attenuation factor is 0.998 3151000300011 (21-SC-44-M,58.6HR,DG,1157.031,0.012) Scandium foil 3151000300012 self-attenuation factor is 0.998 3151000300013 ANALYSIS Data obtained from solution of differential equations 3151000300014 which accounts for all modes of decays (EC and IT). 3151000300015 Fraction of the isomeric decays going to the ground 3151000300016 state was taken as 0.9880+-0.0007. Results of all 3151000300017 measurements for 3 Sc-44 samples were fitted with 3151000300018 least-square method in presentation where experimental 3151000300019 values should lay on straight line 3151000300020 ERR-ANALYS Total uncertainty is given. Main contribution to the 3151000300021 uncertainty (4 to 5%)is due to background in 3151000300022 gamma-spectrum generated by the 2010 keV sum peak 3151000300023 (889+1121) from the decay of Sc-46 3151000300024 CORRECTION Correction due to 1151.313 and 1158.082 keV gamma-ray 3151000300025 interfernces from Ta-182 was always kept below 5% 3151000300026 ENDBIB 24 0 3151000300027 NOCOMMON 0 0 3151000300028 DATA 2 1 3151000300029 DATA ERR-T 3151000300030 MB MB 3151000300031 0.0273 0.0013 3151000300032 ENDDATA 3 0 3151000300033 ENDSUBENT 32 0 3151000399999 SUBENT 31510004 20010213 00003151000400001 BIB 5 24 3151000400002 REACTION (21-SC-45(N,2N)21-SC-44-M,,SIG,,FIS) 3151000400003 DECAY-DATA (21-SC-44-G,3.927HR,DG,1157.031,0.9990) Scandium foil 3151000400004 self-attenuation factor is 0.998 3151000400005 (21-SC-44-M,58.6HR,DG,271.13,0.867) Scandium foil 3151000400006 self-attenuation factor is 0.992 3151000400007 (21-SC-44-M,58.6HR,DG,1001.85,0.0120) Scandium foil 3151000400008 self-attenuation factor is 0.998 3151000400009 (21-SC-44-M,58.6HR,DG,1126.08,0.012) Scandium foil 3151000400010 self-attenuation factor is 0.998 3151000400011 (21-SC-44-M,58.6HR,DG,1157.031,0.012) Scandium foil 3151000400012 self-attenuation factor is 0.998 3151000400013 ANALYSIS Data obtained from solution of differential equations 3151000400014 which accounts for all modes of decays (EC and IT). 3151000400015 Fraction of the isomeric decays going to the ground 3151000400016 state was taken as 0.9880+-0.0007. Results of all 3151000400017 measurements for 3 Sc-44 samples were fitted with 3151000400018 least-square method in presentation where experimental 3151000400019 values should lay on straight line 3151000400020 ERR-ANALYS Total uncertainty is given. Main contribution to the 3151000400021 uncertainty (4 to 5%)is due to background in 3151000400022 gamma-spectrum generated by the 2010 keV sum peak 3151000400023 (889+1121) from the decay of Sc-46 3151000400024 CORRECTION Correction due to 1151.313 and 1158.082 keV gamma-ray 3151000400025 interfernces from Ta-182 was always kept below 5% 3151000400026 ENDBIB 24 0 3151000400027 NOCOMMON 0 0 3151000400028 DATA 2 1 3151000400029 DATA ERR-T 3151000400030 MB MB 3151000400031 0.0220 0.0027 3151000400032 ENDDATA 3 0 3151000400033 ENDSUBENT 32 0 3151000499999 SUBENT 31510005 20010213 00003151000500001 BIB 4 11 3151000500002 REACTION (21-SC-45(N,2N)21-SC-44-M,,SIG,,FIS) 3151000500003 DECAY-DATA (21-SC-44-M,58.6HR,DG,271.13,0.867) Scandium foil 3151000500004 self-attenuation factor is 0.992 3151000500005 ANALYSIS Final value is obtained as weighted averaged 3151000500006 of results of 3 measurements with their statistical 3151000500007 uncertainties (0.0211+-0.0031, 0.0199+-0.0040 and 3151000500008 0.0187+-0.0030 mb). Then systematic uncertainty was 3151000500009 added 3151000500010 ERR-ANALYS Total uncertainty is given. Main contribution to the 3151000500011 uncertainty is due to compound Compton plateau of 3151000500012 of 889- and 1121-keV peaks from Sc-45(n,g) reaction 3151000500013 ENDBIB 11 0 3151000500014 NOCOMMON 0 0 3151000500015 DATA 2 1 3151000500016 DATA ERR-T 3151000500017 MB MB 3151000500018 0.0199 0.0030 3151000500019 ENDDATA 3 0 3151000500020 ENDSUBENT 19 0 3151000599999 ENDENTRY 5 0 3151099999999