ENTRY 23189 20150810 22442318900000001 SUBENT 23189001 20150810 22442318900100001 BIB 9 48 2318900100002 TITLE Determination of the 237Np(n,f) reaction cross section 2318900100003 for En = 4.5-5.3 MeV, using a MicroMegas detector 2318900100004 assembly. 2318900100005 AUTHOR (M.Diakaki, M.Kokkoris, A.Kyrtsos, E.Skordis, 2318900100006 C.T.Papadopoulos, R.Vlastou, A.Lagoyannis, 2318900100007 S.Andriamonje, N.G.Nicolis, E.Berthoumieux) 2318900100008 INSTITUTE (2GRCTUA) M.Diakaki, M.Kokkoris, A.Kyrtsos, E.Skordis, 2318900100009 C.T.Papadopoulos, R.Vlastou, N.G.Nicolis 2318900100010 (2GRCATH) A.Lagoyannis . 2318900100011 (2FR SAC) S.Andriamonje,E.Berthoumieux . 2318900100012 REFERENCE (J,EPJ/A,49,62,2013) Data Table. 2318900100013 #doi:10.1140/epja/i2013-13062-3 2318900100014 (J,NDS,119,52,2014) 2318900100015 #doi:10.1016/j.nds.2014.08.016 2318900100016 Prelim. c-s at EN=5.56+-0.08 MeV on Fig.5. 2318900100017 FACILITY (VDGT,2GRCATH) 5.5MV HV TN-11 Tandem accelerator . 2318900100018 INC-SOURCE (D-D) Monoenergetic neutron beam was produced via the 2318900100019 2H(d,n)3He reaction. Deuterium gas target was bombarded2318900100020 with deuteron beam at energies varied from 2 to 2.6MeV 2318900100021 with step 0.2MeV, at currents around 500 nA - 1 microA.2318900100022 Incident Ed Average Ed,MeV Average En(0-5deg) 2318900100023 MeV (center of gas cell) MeV 2318900100024 2.0 1.39 +- 0.14 4.58 +- 0.14 2318900100025 2.2 1.63 +- 0.13 4.85 +- 0.13 2318900100026 2.4 1.86 +- 0.12 5.09 +- 0.12 2318900100027 2.6 2.08 +- 0.11 5.32 +- 0.11 2318900100028 INC-SPECT The achieved flux was about 5*10**4 n/(cm2*s) in all 2318900100029 four runs performed. 2318900100030 DETECTOR (DRFTC) MicroMegas detector. 2318900100031 Each actinide target served as the detector drift 2318900100032 electrode and was covered by a 0.5mm thick Al mask with2318900100033 a hole of 4 cm diameter. Each Micro-bulk consists of 2318900100034 5 microm perforated copper foil ('micromesh') on 25 or 2318900100035 50 microm thick kapton pillars deposited on 5 microm of2318900100036 a bulk copper foil ('anode'). Detector was filled with 2318900100037 mixture of 80% Argon and 20% CO2 at approximately 2318900100038 atmospheric pressure and the gas was circulated at a 2318900100039 constant flow of 6-8 nl/h. 2318900100040 (SIBAR) The activity of each target was measured with 2318900100041 two silicon surface barrier detectors with different 2318900100042 active surfaces - for mass measurement. Small detector 2318900100043 of 50mm2 area was used to achieve a good resolution, 2318900100044 a big detector of 3000mm2 area -to increase statistics.2318900100045 Calibration of the spectra was done with the use of a 2318900100046 triple 241Am/239Pu/244Cm source. 2318900100047 HISTORY (20120629C) M.M. 2318900100048 (20150810U) M.M. Ref. J,NDS,119,52,2014 was added. 2318900100049 Authors' names N.G.Nicolis,E.Berthoumieux were added. 2318900100050 ENDBIB 48 0 2318900100051 NOCOMMON 0 0 2318900100052 ENDSUBENT 51 0 2318900199999 SUBENT 23189002 20130629 22352318900200001 BIB 8 68 2318900200002 REACTION (93-NP-237(N,F),,SIG) 2318900200003 MONITOR (92-U-238(N,F),,SIG) Standard c-s from NDS web-site 2318900200004 http://www-nds.iaea.org 2318900200005 SAMPLE 237Np and the reference targets 238U and 235U are thin2318900200006 disks of NpO2 and U3O8, deposited on 100 microm Al 2318900200007 backing via the painting technique; were provided by th2318900200008 Institute of Physics and Power Engineering, Obninsk, an2318900200009 the Joint Institute of Nuclear Research, Dubna, Russia,2318900200010 for nTOF collaboration. 2318900200011 Thickness and homogeneity measurements were done via 2318900200012 the Rutherford Backscattering Spectrometry (RBS) 2318900200013 technique at the external ion-beam setup of the 5.5MV 2318900200014 HV TN-11 Tandem accelerator. Targets were found to be 2318900200015 homogeneous, the 238Ufront within 16%, the 238Uback 2318900200016 target within 14%, the 237Np target within 10%, the 2318900200017 235U target within 15%. 2318900200018 - 237Np target properties: 2318900200019 Diameter (cm) 8. 2318900200020 Activity (Bq/mg) 26031+-85 2318900200021 Mass (mg) 6.36+-0.11 2318900200022 Contaminations (mg) 241Am(1.6E-5) 2318900200023 Mean actinide surface concentration(10**15at/cm2) 2318900200024 249+-825 . 2318900200025 - 238U target properties: 2318900200026 Diameter (cm) 5.2 2318900200027 Activity (Bq/mg) 12.44+-0.01 2318900200028 Mass (mg) 9.90+-80.13(front), 9.03+-80.12(back)2318900200029 Mean actinide surface concentration(10**15at/cm2) - 2318900200030 1112+-895, 1120+-8100 2318900200031 - 235U target properties: 2318900200032 Diameter (cm) 5.2 2318900200033 Activity (Bq/mg) 79.98+-0.06 2318900200034 Mass (mg) 4.96+-80.06 2318900200035 Contaminations (mg) 234U(9E-5) 2318900200036 Mean actinide surface concentration(10**15at/cm2) 2318900200037 626+-890 2318900200038 DECAY-DATA (93-NP-237,2.144E+6YR) 2318900200039 (92-U-238,4.468E+9YR) 2318900200040 (92-U-235,7.038E+8YR) 2318900200041 CORRECTION For subthreshold counts 5-7 % . 2318900200042 For efficiency of detection. 2318900200043 For dead time 1.5% for Np-237, for reference target 2318900200044 negligible. 2318900200045 Effect of scattered neutrons was estimated by detailed 2318900200046 Monte Carlo simulations using MCNP5 code and also by 2318900200047 "blank" measurement . 2318900200048 Effect from neutrons of parasitic (d,n) reaction was 2318900200049 estimated by U-235 measurement as monitor and 2318900200050 additional tests performed with HPGE detector to check 2318900200051 energy range of this parasitic neutrons via 2318900200052 Ge74(n,gamma)Ge75m activation reaction (139.68 keV 2318900200053 isomeric state which decays by IT (99.97%) with a 2318900200054 half life of 47.7 s). 2318900200055 ERR-ANALYS (ERR-S) Statistical uncertainty < 3.%. 2318900200056 (ERR-1,1.3,1.7) Uncertainty of target mass. 2318900200057 (ERR-2,,0.5) Uncertainty due to subthreshold counts 2318900200058 correction . 2318900200059 (ERR-3,2.,3.) Uncertainty due to efficiency correction.2318900200060 (ERR-4,3.,4.) Uncertainty of neutron fluence. 2318900200061 (MONIT-ERR,,0.9) U-238 c-s uncertainty < 0.9% . 2318900200062 STATUS (TABLE) Table 3 of J,EPJ/A,49,62,2013 . 2318900200063 COMMENT This research has been co-financed by the European 2318900200064 Union (European Social Fund - ESF) and Greek national 2318900200065 funds through the Operational Program 'Education and 2318900200066 Lifelong Learning' of the National Strategic Reference 2318900200067 Framework (NSRF) - Research Funding Program: 2318900200068 Heracleitus II. Investing in knowledge society through 2318900200069 the European Social Fund. 2318900200070 ENDBIB 68 0 2318900200071 NOCOMMON 0 0 2318900200072 DATA 5 4 2318900200073 EN EN-ERR DATA ERR-S MONIT 2318900200074 MEV MEV B B B 2318900200075 4.58 0.14 1.59 0.05 0.546 2318900200076 4.85 0.13 1.50 0.03 0.548 2318900200077 5.09 0.12 1.50 0.03 0.553 2318900200078 5.32 0.11 1.50 0.03 0.558 2318900200079 ENDDATA 6 0 2318900200080 ENDSUBENT 79 0 2318900299999 ENDENTRY 2 0 2318999999999