ENTRY 23159 20120731 22332315900000001 SUBENT 23159001 20120731 22332315900100001 BIB 12 55 2315900100002 AUTHOR (S.Oberstedt, A.Oberstedt, E.Birgersson,I.Fabry, 2315900100003 F.-J.Hambsch, N.Kornilov, G.Loevestam,A.Tudora) 2315900100004 TITLE First results on the neutron-induced fission cross 2315900100005 section of 231-Pa for incident neutron energies 2315900100006 En > 17 MeV . 2315900100007 INSTITUTE (2ZZZGEL) S.Oberstedt,I.Fabry,F.-J.Hambsch, 2315900100008 G.Loevestam, N.Kornilov . 2315900100009 (2SWDSWD) A.Oberstedt, Dept.of Natural Sciences, 2315900100010 Oerebro University, Sweden 2315900100011 (3RUMBUU) A.Tudora 2315900100012 REFERENCE (J,ANE,43,26,2012) Data Table. 2315900100013 #doi:10.1016/j.anucene.2011.12.023 2315900100014 FACILITY (VDG,2ZZZGEL) 2315900100015 MONITOR (93-NP-237(N,F),,SIG) 2315900100016 METHOD (TOF) 2315900100017 DETECTOR (FISCH) Frisch-gridded fission chamber . 2315900100018 (SCIN) Three NE213 scintillation detectors employing 2315900100019 the pulse-shape discrimination technique for efficient 2315900100020 neutron/gamma-ray separation were placed at 0, 30, 60 2315900100021 degrees relative to the deuteron beam axis and 4.598 m 2315900100022 away from the neutron source and used to measure energy2315900100023 distributions from the neutron source at En = 16, 19, 2315900100024 20,21 MeV. Neutron spectra at 0degree, corrected for 2315900100025 pulse-height dependent efficiency, were used for the 2315900100026 neutron background correction and are shown in Fig.3 2315900100027 of J,ANE,43,26,2012. 2315900100028 The efficiency calibration of the neutron detectors was2315900100029 performed with a 252Cf spontaneous fission source (see 2315900100030 REL-REF of N.Kornilov+). 2315900100031 SAMPLE Pa-231 sample was obtained by means of spray-painting.2315900100032 Original diameter 28 mm was reduced by collimator to 2315900100033 6 mm, effective mass determined by alpha-spectrometry 2315900100034 53.4+-1.3 microgram. 2315900100035 Np-237 sample of 28 mm diameter, mass 182.2 microgram 2315900100036 +- 1.7%, isotopic purity 99.9 %, with negligible 2315900100037 fractions of 238U and 238Pu of less than 2E-7 and 4E-8,2315900100038 respectively. 2315900100039 Protactinium sample was mounted on one side of the 2315900100040 chamber together with a well-characterized 237Np sample2315900100041 in back-to-back geometry. 2315900100042 The distance between sample and neutron source - 60 mm.2315900100043 REL-REF (N,,C.Budtz-Joergensen+,J,NIM/A,258,209,1987) 2315900100044 Details of Frisch-grid fission chamber construction. 2315900100045 (M,,N.V.Kornilov+,J,NIM/A,599,226,2009) 2315900100046 Efficiency calibration details. 2315900100047 CORRECTION Fraction of fission fragments,which are absorbed in the2315900100048 sample due to neutron momentum transfer - estimated 2315900100049 particle leakage amounts to (2.4 +-0.6)% at En = 21MeV.2315900100050 Without any significant error (smaller than 1.5%) 2315900100051 authors assume that, due to considerable energy loss in2315900100052 the target at large emission angles, about half of the 2315900100053 events escape detection. 2315900100054 For alpha-particles pile-up. 2315900100055 For dead time - < 4.%. 2315900100056 HISTORY (20120731C) M.M. 2315900100057 ENDBIB 55 0 2315900100058 NOCOMMON 0 0 2315900100059 ENDSUBENT 58 0 2315900199999 SUBENT 23159002 20120731 22332315900200001 BIB 5 19 2315900200002 REACTION (91-PA-231(N,F),,SIG) 2315900200003 INC-SOURCE (P-T) For reliability check of the experimental set-up,2315900200004 author switched from a deuteron beam to protons in 2315900200005 order to produce neutrons with energies En = 1.95 and 2315900200006 2.95 MeV. Practically the same fission cross-sections 2315900200007 were measured as published by S.Oberstedt+(2005), 2315900200008 which gives evidence for the reproducibility of present2315900200009 results. 2315900200010 REL-REF (A,22910002,S.Oberstedt+,J,ANE,32,1867,2005) 2315900200011 ERR-ANALYS (ERR-T) Total uncertainty include 2315900200012 - the uncertainties in the obtained number of fission 2315900200013 events for 231Pa and 237Np, which comprises both the 2315900200014 statistical as well as the systematic errors, 2315900200015 (MONIT-ERR) the uncertainty in fission cross-section of2315900200016 the reference isotope 237Np, 2315900200017 - the ones of the effective sample masses, 2315900200018 - the uncertainty related to the low-energy neutron 2315900200019 background. 2315900200020 STATUS (TABLE) Table 1 of J,ANE,43,26,2012 . 2315900200021 ENDBIB 19 0 2315900200022 COMMON 1 3 2315900200023 MONIT-ERR 2315900200024 B 2315900200025 0.03 2315900200026 ENDCOMMON 3 0 2315900200027 DATA 6 3 2315900200028 EN EN-RSL-HW DATA -ERR-T +ERR-T MONIT 2315900200029 MEV MEV B B B B 2315900200030 1.95 0.08 1.15 0.08 0.08 1.67 2315900200031 1.95 0.08 1.04 0.04 0.04 1.67 2315900200032 2.95 0.06 1.00 0.04 0.04 1.63 2315900200033 ENDDATA 5 0 2315900200034 ENDSUBENT 33 0 2315900299999 SUBENT 23159003 20120731 22332315900300001 BIB 6 26 2315900300002 REACTION 1(91-PA-231(N,F),,SIG) 2315900300003 2(91-PA-231(N,F),,SIG) 2315900300004 INC-SOURCE (D-T) Quasi monoenergetic neutrons. 2315900300005 Corresponding energy spread of the neutron beams, 2315900300006 calculated with the computer code EnergySet ( see 2315900300007 G.Loevestam, Program to calculate accelerator setting 2315900300008 and neutron yield data for the IRMM VdG laboratory, 2315900300009 IRMM internal report GE/NP/2/2002/06/20.2002), are 2315900300010 given as the difference between maximum and mean 2315900300011 neutron energy. 2315900300012 CORRECTION Two different neutron-background evaluations : 2315900300013 1 -neutron background correction using the activation 2315900300014 data from A.Fessler et al. (2000), 2315900300015 2 -using the neutron beam profiles measured in the frame2315900300016 of the cross-section measurements. 2315900300017 REL-REF 1(R,,A.Fessler+,J,NSE,134,171,2000) 2315900300018 ERR-ANALYS (ERR-T) Total uncertainty include 2315900300019 - the uncertainties in the obtained number of fission 2315900300020 events for 231Pa and 237Np, which comprises both the 2315900300021 statistical as well as the systematic errors, 2315900300022 (MONIT-ERR) the uncertainty in fission cross-section of2315900300023 the reference isotope 237Np, 2315900300024 - the ones of the effective sample masses, 2315900300025 - the uncertainty related to the low-energy neutron 2315900300026 background. 2315900300027 STATUS (TABLE) Table 1 of J,ANE,43,26,2012 . 2315900300028 ENDBIB 26 0 2315900300029 NOCOMMON 0 0 2315900300030 DATA 9 12 2315900300031 EN EN-RSL-HW DATA 1-ERR-T 1+ERR-T 1DATA 22315900300032 ERR-T 2MONIT MONIT-ERR 2315900300033 MEV MEV B B B B 2315900300034 B B B 2315900300035 15.0 0.7 1.54 0.15 0.15 1.51 2315900300036 0.20 2.24 0.04 2315900300037 15.3 0.8 1.55 0.15 0.15 1.51 2315900300038 0.20 2.26 0.05 2315900300039 15.9 0.8 1.62 0.15 0.15 1.58 2315900300040 0.21 2.27 0.05 2315900300041 17.2 0.6 1.71 0.17 0.24 1.61 2315900300042 0.22 2.28 0.05 2315900300043 17.2 0.6 1.62 0.17 0.22 1.52 2315900300044 0.21 2.28 0.05 2315900300045 17.7 0.6 1.68 0.18 0.26 1.58 2315900300046 0.21 2.28 0.05 2315900300047 18.3 0.5 1.62 0.18 0.28 1.51 2315900300048 0.20 2.27 0.05 2315900300049 18.8 0.5 1.61 0.18 0.32 1.49 2315900300050 0.20 2.27 0.05 2315900300051 19.3 0.5 1.60 0.19 0.37 1.53 2315900300052 0.21 2.27 0.05 2315900300053 19.8 0.5 1.63 0.20 0.45 1.69 2315900300054 0.23 2.27 0.05 2315900300055 20.4 0.5 1.65 0.22 0.52 1.52 2315900300056 0.20 2.29 0.05 2315900300057 20.9 0.5 1.79 0.26 0.75 1.54 2315900300058 0.21 2.31 0.05 2315900300059 ENDDATA 28 0 2315900300060 ENDSUBENT 59 0 2315900399999 SUBENT 23159004 20120731 22332315900400001 BIB 5 19 2315900400002 REACTION (91-PA-231(N,F),,SIG) 2315900400003 ANALYSIS Fission cross-section and its total uncertainty are 2315900400004 calculated individually for both ways of data 2315900400005 treatment, and then averaged - weighted by their 2315900400006 individual uncertainties. 2315900400007 ERR-ANALYS (ERR-T) Total uncertainty include 2315900400008 - the uncertainties in the obtained number of fission 2315900400009 events for 231Pa and 237Np, which comprises both the 2315900400010 statistical as well as the systematic errors, 2315900400011 (MONIT-ERR) the uncertainty in fission cross-section of2315900400012 the reference isotope 237Np, 2315900400013 - the ones of the effective sample masses, 2315900400014 - the uncertainty related to the low-energy neutron 2315900400015 background. 2315900400016 REL-REF (A,21731003,O.Birgul+,J,RCA,11,108,1969) 2315900400017 (D,10929002,S.Plattard+,J,PRL,46,633,1981) 2315900400018 STATUS (TABLE) Table 1 of J,ANE,43,26,2012 . 2315900400019 (DEP,23159003) Average of two treatments given in 2315900400020 Subent 003. 2315900400021 ENDBIB 19 0 2315900400022 NOCOMMON 0 0 2315900400023 DATA 7 12 2315900400024 EN EN-RSL-HW DATA -ERR-T +ERR-T MONIT 2315900400025 MONIT-ERR 2315900400026 MEV MEV B B B B 2315900400027 B 2315900400028 15.0 0.7 1.52 0.18 0.18 2.24 2315900400029 0.04 2315900400030 15.3 0.8 1.54 0.18 0.18 2.26 2315900400031 0.05 2315900400032 15.9 0.8 1.61 0.18 0.19 2.27 2315900400033 0.05 2315900400034 17.2 0.6 1.66 0.20 0.23 2.28 2315900400035 0.05 2315900400036 17.2 0.6 1.57 0.19 0.21 2.28 2315900400037 0.05 2315900400038 17.7 0.6 1.63 0.20 0.24 2.28 2315900400039 0.05 2315900400040 18.3 0.5 1.56 0.19 0.25 2.27 2315900400041 0.05 2315900400042 18.8 0.5 1.54 0.19 0.27 2.27 2315900400043 0.05 2315900400044 19.3 0.5 1.56 0.20 0.30 2.27 2315900400045 0.05 2315900400046 19.8 0.5 1.67 0.22 0.35 2.27 2315900400047 0.05 2315900400048 20.4 0.5 1.56 0.21 0.40 2.29 2315900400049 0.05 2315900400050 20.9 0.5 1.61 0.23 0.55 2.31 2315900400051 0.05 2315900400052 ENDDATA 28 0 2315900400053 ENDSUBENT 52 0 2315900499999 ENDENTRY 4 0 2315999999999