ENTRY 30925 20090913 31413092500000001 SUBENT 30925001 20090913 31413092500100001 BIB 18 126 3092500100002 TITLE Measurement of the cross section for the reaction 3092500100003 93-Nb(n,inl)Nb-93m at 2.8 MeV 3092500100004 AUTHOR (M.Wagner,G.Winkler,H.Vonach,G.Peto) 3092500100005 INSTITUTE (3HUNKOS) The last author. 3092500100006 (2AUSIRK) The 3 first authors. 3092500100007 REFERENCE (J,ANE,15,(7),363,1988) 3092500100008 SAMPLE Nb foils 20mm dia,x0.13mm thick and mass of 364.24 mg 3092500100009 purity of Nb foils better than 99.9%. 3092500100010 MONITOR (92-U-238(N,F),,SIG) The fission chamber served to 3092500100011 measure the neutron fluence, was operated as an 3092500100012 ionization chamber with a voltage gradient of 600 V/cm3092500100013 and a continuous gas flow of pure Ar as counting gas. 3092500100014 The fissionable material was 238U enriched to 99.98% 3092500100015 in the form of U-F4. The ratio of the 238-U(n,F) and 3092500100016 27-Al(n,a) cross section at 14.8 MeV was used as 3092500100017 monitor for the calibration of the fissionable 3092500100018 deposit mass. 3092500100019 FACILITY (CCW,3HUNKOS) Irradiations facility. 3092500100020 METHOD (ACTIV) 3092500100021 (MOSEP) 3092500100022 -The cross section for the reaction 93-Nb(n,inl)Nb-93-m3092500100023 was measured by foil activation at the neutron energy 3092500100024 of 2.83 MeV relative to the 238-U(n,f) cross section 3092500100025 employing a small ionization chamber as fluence 3092500100026 monitor. 3092500100027 -The induced 93m-Nb activity was assessed by 3092500100028 measuring the K-shell X-rays from the 30.7keV isomeric3092500100029 transition. 3092500100030 -The mass of the fissionable deposit was calibrated 3092500100031 relative to the mass of an Al foil by means of an 3092500100032 irradiation experiment at 14.8 MeV using the ratio of 3092500100033 the 238-U(n,f) and 27-Al(n,a)Na-24 cross section. 3092500100034 -The Ni foils served to measure the fluence gradient 3092500100035 via the 58-Co activity induced. 3092500100036 INC-SOURCE (D-D) D beam with incident energy of (220+-5)keV and 3092500100037 current of about 250 micro-Amp. 3092500100038 INC-SPECT The effective mean neutron energy was adopted to be: 3092500100039 2.83+-0.04 MeV for the Nb and Ni foils with 20mm dia.3092500100040 2.87+-0.04 MeV for the 238-U layer and Ni foils with 3092500100041 10mm dia. 3092500100042 The effects of the various uncertainty components 3092500100043 are mentioned in Tab I of the present work. 3092500100044 DETECTOR (SILI)The characteristic Nb K-shell X-rays emitted 3092500100045 after internal conversion of the 30.7keV 3092500100046 transition to the ground state, was detected by 3092500100047 Si-Li detector,with diameter of the active vol.:3092500100048 25mm, thickness:5mm, Be window:0.0125mm and 3092500100049 resolution:approx. 400 eV at 17 keV. 3092500100050 In order to accurately measure the 93m-Nb acti- 3092500100051 vity the employed X-ray detector was calibrated 3092500100052 with respect to its efficiency for the Nb 3092500100053 K-shell X-rays. 3092500100054 RAD-DET (41-NB-93-M,XR) 3092500100055 DECAY-DATA (41-NB-93-M,16.1YR,XR) The value for half-life was 3092500100056 taken from PTB-RA-16/2,1986. 3092500100057 MONIT-REF (,W.P.POENITZ,W,POENITZ,1988) (ENDF/B-V1,1986) 3092500100058 CORRECTION 1.-The conversion factor for the fluence in the foils 3092500100059 with 20-mm dia to the fluence in the U-layer with 3092500100060 10 mm dia was experimentally determined by measuring3092500100061 the activity of the ring-shaped part and the central3092500100062 part (dia 10mm)of the inner Ni foil separately,thus 3092500100063 taking into account the decrease of the neutron flux3092500100064 with increasing angle 3092500100065 2.-In order to estimate the enhancement of the count 3092500100066 rate in the Nb K-shell X-ray peaks due to the 3092500100067 influence of the Ta inpurities in the Nb sample, a 3092500100068 0.1mm thick Ta foil(20mm dia) was simultaneously 3092500100069 irradiated, and the induced 182-Ta activity measured3092500100070 afterwards. 3092500100071 3.-Corrections had to be applied to the recorded 3092500100072 fission fragment spectra for the extrapolation from 3092500100073 the bias level to zero pulse height and for self 3092500100074 absorption of the fission fragments considering 3092500100075 reaction kinematics and angular distribution of the 3092500100076 fragments. 3092500100077 4.-Correction for the background effect.It was essent- 3092500100078 ial to measure the background spectrum using a Nb 3092500100079 foil of the same dimensions as the irradiated foil, 3092500100080 but not activated by neutrons. 3092500100081 5.-The increase of the m-93-Nb activity by neutrons 3092500100082 elastically scattered by the Nb foil and unscattered3092500100083 by adjacent material was estimated 3092500100084 6.-Source effects were taken into account determining 3092500100085 experimentally the self-attenuation of the measured 3092500100086 X-radiation and considering the extension and 3092500100087 inhomogeneous activation of the source 3092500100088 ERR-ANALYS (ERR-T) Source of uncertainty Uncertainty(%)3092500100089 I-measurement of the 93-Nb activity: 3092500100090 (ERR-S) Counting statistics including the K-shell X-ray3092500100091 fluorescence caused by the background radiation 1.093092500100092 (ERR-1) Efficiency of the Si(Li) detector for Nb 3092500100093 K-shell X-radiation,averaged over the sample area 0.983092500100094 (ERR-2) Reproducibility of the geometry 0.403092500100095 (ERR-3) Self-attenuation in the Nb sample 0.653092500100096 (ERR-4) Half-life of Nb-93m,survival factor,timing; 3092500100097 together 1.243092500100098 Additionally: 3092500100099 -Correction for K-shell x-ray fluorescence caused 3092500100100 by Ta impurity in the Nb sample 0.103092500100101 -Correction for activation enhancement due to 3092500100102 elastic neutron scattering 0.023092500100103 II-Mass of the Nb sample negligible3092500100104 III-Fluence related measurements: 3092500100105 (ERR-5) Extrapolation correction for fissions 0.333092500100106 (ERR-6) Correction for finite thickness 3092500100107 of the deposit 0.203092500100108 (ERR-7) Fluence extrapolation from sample to reference 3092500100109 deposit including fluence gradient and 3092500100110 irradiation geometry uncertainty 2.813092500100111 (ERR-8) 238-U(n,f) reference cross section at 2.87 MeV 3092500100112 according to ENDF/B-VI 1.003092500100113 (ERR-9) Neutron energy uncertainty contribution 3092500100114 therein 0.31 3092500100115 (ERR-10) Total uncertainty of the 238-U-deposit mass, 3092500100116 including interference from other isotopes 1.493092500100117 Additionally: 3092500100118 -Fission-fragment-counting statistics 0.073092500100119 -Correction for 14MeV-neutron contamination 0.043092500100120 IV-Net correction for inelastic neutron scattering 0.063092500100121 (ERR-11) -Energy uncertainty combined with slope of the3092500100122 93-Nb(n,inl)Nb-93-m cross section 1.703092500100123 STATUS (TABLE) Data taken from J,ANE,vol(15) pag.363,1988. 3092500100124 HISTORY (19880902C) VOF 3092500100125 (20090912A) SD:Updated to new date formats,lower case. 3092500100126 Cosmetic changes, codes for partial uncertainties and 3092500100127 data to COMMON section were added 3092500100128 ENDBIB 126 0 3092500100129 COMMON 12 6 3092500100130 ERR-S ERR-1 ERR-2 ERR-3 ERR-4 ERR-5 3092500100131 ERR-6 ERR-7 ERR-8 ERR-9 ERR-10 ERR-11 3092500100132 PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT 3092500100133 PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT 3092500100134 1.09 0.98 0.40 0.65 1.24 0.33 3092500100135 0.20 2.81 1.0 0.31 1.49 1.70 3092500100136 ENDCOMMON 6 0 3092500100137 ENDSUBENT 136 0 3092500199999 SUBENT 30925002 20090913 31413092500200001 BIB 1 1 3092500200002 REACTION (41-NB-93(N,INL)41-NB-93-M,,SIG) 3092500200003 ENDBIB 1 0 3092500200004 NOCOMMON 0 0 3092500200005 DATA 6 1 3092500200006 EN DATA ERR-T EN-ERR MONIT MONIT-ERR 3092500200007 MEV MB MB MEV MB PER-CENT 3092500200008 2.83 252.4 10.9 0.04 523.2 1.0 3092500200009 ENDDATA 3 0 3092500200010 ENDSUBENT 9 0 3092500299999 ENDENTRY 2 0 3092599999999