ENTRY 31533 20040714 00003153300000001 SUBENT 31533001 20040714 00003153300100001 BIB 16 104 3153300100002 TITLE Thermal neutron cross section and resonance integral 3153300100003 of the 159Tb(n,g)160Tb reaction 3153300100004 AUTHOR (M.U.Rajput,M.Ahmad,W.Ahmad) 3153300100005 INSTITUTE (3PAKNIL) 3153300100006 REFERENCE (J,PR/C,68,044608,2003) 3153300100007 FACILITY (REAC) Pakistan Research reactor-1 at PINSTECH. 3153300100008 The reactor core contains 20% LEU fuel. 3153300100009 SAMPLE The targets of the terbium were prepared from spectro- 3153300100010 graphically pure powder Tb4O7 from Merck. A small 3153300100011 quantity of terbium powder (2-6 mg) was spread onto 3153300100012 a Whatman-1 filter paper,covering a relatively large 3153300100013 circular foils of about 8-10 mm in diam. Four samples 3153300100014 were prepared for bare irradiation and another four 3153300100015 for irradiation under a cadmium cover. The weighing of 3153300100016 the target materials was carefully carried out using a 3153300100017 Sartorius semimicro electrical balance. 3153300100018 DETECTOR (HPGE) The gamma ray spectrometry of the irradiated 3153300100019 samples was carried out using a high-resolution 3153300100020 ganuna ray detection system. The system employed a 3153300100021 40% relative efficiency high purity germanium detector 3153300100022 with energy resolution of 2.0 keV at the 1332.5 keV 3153300100023 peak of 60Co. The induced activities in the terbium 3153300100024 samples were determined by measuring the y rays at 3153300100025 298, 879, and 1177 keV associated with the decay of 3153300100026 160Tb while counting the samples at source-detector 3153300100027 distances of 25 and 15 cm. 3153300100028 METHOD (ACTIV) 3153300100029 The irradiations of the activation detectors of Au, Co,3153300100030 Mn, and Zn were carried out to characterize the neutron3153300100031 irradiation facility. The targets of Au weighing 1-4 mg3153300100032 were prepared from thin gold foils of thickness 30 mu-m3153300100033 The cobalt samples (6-10 mg) were made from 10-mil 3153300100034 cobalt wire.The wires were cut into roughly equal 3153300100035 pieces of length 2 cm and rolled spirally. The 3153300100036 manganese samples (2-4 mg) were made from manganese 3153300100037 metallicpieces. Zinc foils (approx.2 mg) of 8 mm diam. 3153300100038 were used. For the determination of the alpha deviation3153300100039 parameter, these activation detectors were packaged 3153300100040 together in standard polystyrene irradiation capsules 3153300100041 of dimension 13.5 mm in diameter and height 11 mm for 3153300100042 bare irradiation and another set of detectors was 3153300100043 packaged into a cadmium box of dimension 14 mm diam., 3153300100044 height 6 mm, and thickness 1 mm. Each of the activation3153300100045 detectors was also encapsulated individually within 3153300100046 polystyrene and cadmium covers for the determination 3153300100047 of thermal and epithermal neutron fluxes and cadmium 3153300100048 ratios. 3153300100049 CORRECTION Thermal and epithermal correction factors were used 3153300100050 in the determination of the thermal neutron capture 3153300100051 cross section (the cross section at 2200 m/sec) 3153300100052 and resonance integral (epithermal neutrons in the 3153300100053 1/E region) for the rare-earth nuclide Terbium-159. 3153300100054 Thermal and epithermal correction factors were 3153300100055 calculated by using the expression described by 3153300100056 Zweifel (Nucleonics,18,174,1960) and 3153300100057 Baumann (AEC Report DP-817, 1963). 3153300100058 Paramenter alpha, which determines deviation of 3153300100059 thermalized neutron spectrum from 1/E dependance as: 3153300100060 alpha - (1/E)**(1+alpha) 3153300100061 was measured as alpha = -0.1623+-0.0055 3153300100062 MONITOR (25-MN-55(N,G)25-MN-56,,RI) (1) 3153300100063 (30-ZN-64(N,G)30-ZN-65,,RI) (2) 3153300100064 Reactions 1,2 are used for 1/E deviation parameter 3153300100065 (27-CO-59(N,G)27-CO-60,,SIG) 3153300100066 (27-CO-59(N,G)27-CO-60,,RI) 3153300100067 (79-AU-197(N,G)79-AU-198,,SIG) 3153300100068 (79-AU-197(N,G)79-AU-198,,RI) 3153300100069 All others are used for deviation parameter and 3153300100070 cross section monitor. Cross sections are not given. 3153300100071 DECAY-MON (25-MN-56,0.107454D,DG,846.7715,0.989, 3153300100072 DG,1173.237,0.999736) 3153300100073 Errors in data are: in half life: +-0.000004; 3153300100074 in probability (846.77715) : +-0.003 3153300100075 in probability (1173.237) : +-0.000007 3153300100076 (27-CO-60-G,1925.1D,DG,1332.501,0.999856) 3153300100077 Errors in data are: Half life: +-0.5; 3153300100078 in probability (1332.501) : +-0.000004 3153300100079 (30-ZN-65,244.26D,DG,1115.546,0.5060) 3153300100080 Errors in data are: in half life: +-0.26; 3153300100081 in probability (1115.546) : +-0.0022 3153300100082 (79-AU-198,2.69517D,DG,411.80203,0.9558) 3153300100083 Errors in data are: Half life: +-0.0.00021; 3153300100084 in probability (411.80203) : +-0.0.0012 3153300100085 DECAY-DATA (65-TB-160,72.3D,DG,298.58,0.261, 3153300100086 DG,879.383,0.301, 3153300100087 DG,1177.962,0.149) 3153300100088 Errors in data are: in half life: +-0.2; 3153300100089 in probability (298.58) : +-0.006 3153300100090 in probability (879.383) : +-0.006 3153300100091 in probability (1177.962) : +-0.003 3153300100092 ERR-ANALYS (ERR-T) The uncertainties in the overall measurements 3153300100093 include: 3153300100094 (i) statistical errors, 3153300100095 (ii) the error in the interpolated efficiencies, 3153300100096 (iii) errors in the nuclear data (see DECAY-MON and 3153300100097 DECAY-DATA), 3153300100098 (iv) target weighing errors. 3153300100099 COMMENT All decay data were taken from: 3153300100100 S.Y.F.Chu+, LBNL report 1999, and Evaluated Nuclear 3153300100101 Structure Data File (ENDSF), a computer file of 3153300100102 evaluated experimental nuclear structure data, 3153300100103 processed by RADLIST, IAEA NuDat Retrieval. 3153300100104 STATUS (TABLE) Data from the tbl.3 of this paper 3153300100105 HISTORY (20040121C) SD 3153300100106 ENDBIB 104 0 3153300100107 NOCOMMON 0 0 3153300100108 ENDSUBENT 107 0 3153300199999 SUBENT 31533002 20040714 00003153300200001 BIB 1 2 3153300200002 REACTION (65-TB-159(N,G)65-TB-160,,SIG) Cross section is the 3153300200003 thermal neutron capture cross section at 2200 m/sec 3153300200004 ENDBIB 2 0 3153300200005 NOCOMMON 0 0 3153300200006 DATA 3 1 3153300200007 EN DATA ERR-T 3153300200008 EV B B 3153300200009 0.0253 23.6 0.4 3153300200010 ENDDATA 3 0 3153300200011 ENDSUBENT 10 0 3153300299999 SUBENT 31533003 20040714 00003153300300001 BIB 1 1 3153300300002 REACTION (65-TB-159(N,G)65-TB-160,,RI) 3153300300003 ENDBIB 1 0 3153300300004 NOCOMMON 0 0 3153300300005 DATA 3 1 3153300300006 EN-MIN DATA ERR-T 3153300300007 EV B B 3153300300008 0.5 443. 21. 3153300300009 ENDDATA 3 0 3153300300010 ENDSUBENT 9 0 3153300399999 ENDENTRY 3 0 3153399999999