ENTRY 23114 20170322 22582311400000001 SUBENT 23114001 20170322 22582311400100001 BIB 17 122 2311400100002 TITLE High resolution measurements of the 241Am(n,2n) 2311400100003 reaction cross section 2311400100004 AUTHOR (C.Sage, V.Semkova, O.Bouland, P.Dessagne, A.Fernandez,2311400100005 F.Gunsing, C.Naestren, G.Noguere, H.Ottmar, 2311400100006 A.J.M.Plompen, P.Romain, G.Rudolf, J.Somers, F.Wastin)2311400100007 INSTITUTE (2FR SAC,2ZZZGEL,2FR CAD,2FR STR,3BULBLA,1USALAS, 2311400100008 2ZZZITU,2FR BRC) 2311400100009 REFERENCE (J,PR/C,81,064604,2010) 2311400100010 #doi:10.1103/PhysRevC.81.064604 2311400100011 (R,INDC(FR)-73,2017) 2311400100012 Derivation of full covariance matrix, 2311400100013 Sage's thesis submitted to Univ. Strasbourg. (Nov.2009)2311400100014 REL-REF (R,A1007001,H.Liskien+,J,ND/A,11,569,1973) 2311400100015 c.s. used for neutron spectra 2311400100016 (R,,A.B.Smith+,R,ANL-NDM-115,1990) 2311400100017 c.s. for unfolding with 115In(n,n')115In 2311400100018 (R,,M.Wagner+,B,PH-DAT,13-5,1990) 2311400100019 c.s. for unfolding with 27Al(n,a) and 93Nb(n,2n) 2311400100020 FACILITY (VDGT,2ZZZGEL) 7-MV Van de Graaff accelerator 2311400100021 INC-SOURCE Typical beam current on the target 10 uA. 2311400100022 (D-D) 8.34 and 9.15 MeV neutrons by 5.5, 6.3 MeV 2311400100023 deuterons using D2 gas target cell of 4 cm length, 2311400100024 4 cm diameter, with Mo entrance window at 120 kPa. 2311400100025 Samples were placed 1.5 cm from neutron production 2311400100026 target. 2311400100027 (D-T) 16.1 to 20.6 MeV neutrons from solid-state 2311400100028 Ti/H-3 target of 2 mg/cm2 thickness on Ag backing of 2311400100029 0.4 mm thickness. 2311400100030 Samples were placed at 0 deg at 2 cm distance from 2311400100031 neutron production target. 2311400100032 13.3 MeV neutrons by 1 MeV deuterons. 2311400100033 Sample were placed at 125 deg at 3.9 cm distance from 2311400100034 neutron production target. 2311400100035 INC-SPECT Quasi-mono-energetic neutron flux 5.E+7 n/sec/cm2. 2311400100036 Mean neutron energy and yield distributions were 2311400100037 calculated by code ENERGYSET based on 2311400100038 - cross section evaluations of H.Liskien+ (1973); 2311400100039 - energy-loss estimates with stopping powers of 2311400100040 H.H.Andersen et al., "Hydrogen stopping powers and 2311400100041 ranges in all elements", Pergamon, New York, 1977. 2311400100042 To account for contribution of low threshold energies 2311400100043 reaction, neutron flux density distributions were 2311400100044 determined using previously measured TOF spectra 2311400100045 combined with the spectral index method involving 2311400100046 various reactions used for unfolding: 2311400100047 115In(n,n')115mIn (A.B.Smith+, 1990), 2311400100048 27Al(n,a)24Na (M.Wagner+, 1990), 2311400100049 93Nb(n,2n)92mNb (M.Wagner+, 1990), 2311400100050 27Al(n,p)27Mg (ENDF/B-VI), 2311400100051 56Fe(n,p)56Mn (ENDF/B-VI), 2311400100052 58Ni(n,p)58Co (ENDF/B-VI) . 2311400100053 DETECTOR (HPGE) Pb/Sn/Cu shielding of 5/3/3 mm thickness, 2311400100054 respectively, to reduce 241Am natural activity to 2311400100055 limit the dead time of the system to <15% (between 2311400100056 7% and 15%, typically). 2311400100057 Co-60 standard source was used to check correctness of 2311400100058 dead time given by acquisition system Maestro (Ortec).2311400100059 Additional shielding of 10-mm-thick Cu cylinder to 2311400100060 avoid detection of scattered gamma-rays. 2311400100061 Gamma-ray spectra were analyzed using the software 2311400100062 package Genie2000 of Canberra. 2311400100063 Energy calibration was made by standard sources: 2311400100064 241Am(59.5 keV), 109Cd(88 keV), 57Co(122.1,136.5 keV),2311400100065 137Cs(661.66 keV), 54Mn(834.8 keV), 65Zn(1115.5 keV) 2311400100066 for different radial positions and detector-source 2311400100067 distance. 2311400100068 The efficiency was determined by MCNP5 taking into 2311400100069 account the entire detection geometry. 2311400100070 Results of simulation were compared with measured 2311400100071 values and efficiency curves by fitting experimental 2311400100072 points with polynomial logarithmic functions. 2311400100073 Detector geometry parameters have been optimized to 2311400100074 obtain agreement between measurements and simulations 2311400100075 within the uncertainty limits. 2311400100076 (BF3) BF3-counter operated in multichannel-scaling 2311400100077 acquisition mode - to record the time profile on 2311400100078 neutron flux. 2311400100079 METHOD (ACTIV,GSPEC) 2311400100080 The intensities of the two main gamma-rays emitted in 2311400100081 the decay of 240Am were measured as a function of 2311400100082 cooling time after irradiation. 2311400100083 SAMPLE The Am samples were prepared at JRC, ITU, Karlsruhe, 2311400100084 by method based on production of porous alumina 2311400100085 granules by powder metallurgy. 2311400100086 Resulting powder was pressed into pellets of 12 mm 2311400100087 diameter, 2mm thickness. 2311400100088 Sample weight was on average 400 mg, average Am 2311400100089 content was 40 mg. Encapsulated in Al containers. 2311400100090 -------------------------------------------------- 2311400100091 Total mass 241Am content Al2O3 241Am Calc'd 2311400100092 g mg g wt% 2311400100093 -------------------------------------------------- 2311400100094 0.342 32.2+/-0.1 0.305 9.43 2311400100095 0.442 42.2+/-0.1 0.394 9.51 2311400100096 0.428 40.3+/-0.1 0.382 9.42 2311400100097 0.435 41.0+/-0.1 0.388 9.42 2311400100098 0.448 41.2+/-0.1 0.401 9.20 2311400100099 0.447 42.1+/-0.1 0.399 9.42 . 2311400100100 -------------------------------------------------- 2311400100101 Distance between monitor foils and sample was 3 mm in 2311400100102 front, 10 mm at back. 2311400100103 MONITOR (13-AL-27(N,A)11-NA-24,,SIG) 2311400100104 DECAY-MON (11-NA-24,14.997HR,DG,1368.6,0.999936) 2311400100105 14.997+/-0.012 hr, 99.9936+/-0.0015% 2311400100106 MONIT-REF (,M.Wagner+,B,PH-DAT,13-5,1990) 2311400100107 (,H.Vonach,R,INDC(SEC)-101,75,1992) 2311400100108 DECAY-DATA Decay data used for neutron flux unfolding 2311400100109 (12-MG-27,9.458MIN,DG,843.8,0.718) 2311400100110 9.458+/-0.012 min, 71.8+/-0.4% 2311400100111 (25-MN-56,2.5789HR,DG,846.8,0.989) 2311400100112 2.5789+/-0.0001 hr, 98.9+/-0.3% 2311400100113 (49-IN-115-M,4.486HR,DG,336.2,0.46) 2311400100114 4.486+/-0.004 hr, 46+/-2% 2311400100115 (41-NB-92-M,10.15D,DG,934.4,0.9907) 2311400100116 10.15+/-0.02 d, 99.07+/-0.04% 2311400100117 (27-CO-58-G,70.86D,DG,810.8,0.9945) 2311400100118 70.86+/-0.07 d, 99.45+/-0.01% 2311400100119 STATUS (APRVD) V.Semkova (2010-10-19) 2311400100120 HISTORY (20100924C) M.M. 2311400100121 (20120120A) NDS(VZ): REL-REF: ND/B->NDS 2311400100122 (20130924U) On. BIB updated. 2311400100123 (20170322U) On. REFERENCE and REL-REF updated. 2311400100124 ENDBIB 122 0 2311400100125 NOCOMMON 0 0 2311400100126 ENDSUBENT 125 0 2311400199999 SUBENT 23114002 20130924 22362311400200001 BIB 10 81 2311400200002 REACTION (95-AM-241(N,2N)95-AM-240,,SIG) 2311400200003 DECAY-DATA (95-AM-240,50.8HR,DG,987.79,0.722) 2311400200004 50.8+/-0.3 hr, 987.79+/-0.06 keV, 72.2+/-0.9% 2311400200005 The 987.79-keV line is free of interference, while the 2311400200006 888.85 keV gamma line is contaminated by the natural 2311400200007 activity of the sample itself. 2311400200008 Only 987.79 keV gamma line was used for cross section 2311400200009 determination. 2311400200010 REL-REF (R,,B.Singh+,J,NDS,109,2439,2008) 2311400200011 Decay data for A=240 2311400200012 (R,,M.S.Basunia,J,NDS,107,2323,2006) 2311400200013 Decay data for A=237 2311400200014 (A,14172003,A.P.Tonchev+,J,PR/C,77,054610,2008) 2311400200015 (A,22936002,G.Perdikakis+,J,PR/C,73,067601,2006) 2311400200016 (A,41240071,A.A.Filatenkov+,J,PAN,63,1504,2000) 2311400200017 (D,13883003,R.W.Lougheed+,J,RCA,90,833,2002) 2311400200018 CORRECTION Corrections were done for 2311400200019 - photon absorption, including the disk shape of the 2311400200020 samples and monitor foils, were calculated using 2311400200021 MCNP5 simulation of the detection geometry, have 2311400200022 been incorporated in the efficiency and were 2311400200023 estimated to 0.2% and 1.3%, respectively. 2311400200024 - coincidence summings of gamma-rays: 2311400200025 25.4% for 27Al(n,a) 1368.6 keV 2311400200026 0.3% for 27Al(n,p) 843.8 keV 2311400200027 13.5% for 58Ni(n,p) 810.8 keV 2311400200028 0.4% for 93Nb(n,2n) 934.4 keV 2311400200029 9.9% for 56Fe(n,p) 846.8 keV 2311400200030 - neutron flux fluctuations (MISC1,MISC2) 2311400200031 - low-energy breakup neutrons (MISC3,MISC4) 2311400200032 MISC-COL (MISC1) Flux fluctuation correction factor for Am 2311400200033 (MISC2) Flux fluctuation correction factor for Al 2311400200034 (MISC3) Low energy correction factor for Am 2311400200035 (MISC4) Low energy correction factor for Al 2311400200036 ADD-RES TALYS, ENDF/B-VII, JENDL-3.3 agree each other; 2311400200037 BROND-2.2 close to exp. data only above 18 MeV. 2311400200038 ERR-ANALYS (ERR-T,,,P) Total uncertainty 2311400200039 (MONIT-ERR,,,P) 27Al(n,a) standard x-section (1.6-5.4%)2311400200040 (ERR-1,,,U) Counting of 240Am activity (1.4-6.3%)2311400200041 (ERR-2,,,U) Counting of 24Na activity (0.7-2.0%)2311400200042 (ERR-3,,,F) Intensity of 240Am gamma line (1.2%)2311400200043 (ERR-4,,,U) Number of 27Al in sample (0.1%)2311400200044 (ERR-5,,,P) Number of 241Am in sample (0.3%)2311400200045 (ERR-6,,,F) 24Na/240Am efficiency ratio (3.0%)2311400200046 (ERR-7,,,F) Correction for decay of 240Am (0.4-0.9%)2311400200047 (ERR-8,,,U) Correction for secondary neutron (<1.4%)2311400200048 COVARIANCE (XY,9,EN,MEV) incident neutron energy 2311400200049 8.34 9.15 13.33 16.10 17.16 17.90 19.36 19.95 20.61 2311400200050 (Z,45,COR:ERR-T,PER-CENT) macro-correlation 2311400200051 100 2311400200052 35 100 2311400200053 37 42 100 2311400200054 38 43 53 100 2311400200055 40 45 57 58 100 2311400200056 41 45 57 59 84 100 2311400200057 21 24 30 31 39 39 100 2311400200058 30 34 44 45 58 59 51 100 2311400200059 20 22 29 30 40 42 39 65 100 2311400200060 (Z,45,COR:MONIT-ERR,PER-CENT) micro-corr.(standard) 2311400200061 100 2311400200062 43 100 2311400200063 0 0 100 2311400200064 0 0 6 100 2311400200065 0 0 9 12 100 2311400200066 0 0 9 12 100 100 2311400200067 0 0 11 11 40 40 100 2311400200068 0 0 11 11 40 40 100 100 2311400200069 0 0 11 11 40 40 100 100 100 2311400200070 (Z,45,COR:ERR-5,PER-CENT) micro-corr. (sample mass) 2311400200071 100 2311400200072 0 100 2311400200073 0 100 100 2311400200074 0 100 100 100 2311400200075 0 0 0 0 100 2311400200076 100 0 0 0 0 100 2311400200077 0 0 0 0 100 0 100 2311400200078 0 0 0 0 0 0 0 100 2311400200079 100 0 0 0 0 100 0 0 100 2311400200080 STATUS (TABLE) Table V of Phys.Rev.C81(2010)064604, 2311400200081 Appendix B of Sage's thesis (micro correlation)2311400200082 HISTORY (20130924A) On. ERR-ANALYS, COVARIANCE etc. 2311400200083 ENDBIB 81 0 2311400200084 COMMON 4 3 2311400200085 ERR-3 ERR-4 ERR-5 ERR-6 2311400200086 PER-CENT PER-CENT PER-CENT PER-CENT 2311400200087 1.2 0.1 0.3 3.0 2311400200088 ENDCOMMON 3 0 2311400200089 DATA 13 9 2311400200090 EN EN-ERR DATA ERR-T MONIT-ERR ERR-1 2311400200091 ERR-2 ERR-7 ERR-8 MISC1 MISC2 MISC3 2311400200092 MISC4 2311400200093 MEV MEV MB PER-CENT PER-CENT PER-CENT 2311400200094 PER-CENT PER-CENT PER-CENT NO-DIM NO-DIM NO-DIM 2311400200095 NO-DIM 2311400200096 8.34 0.15 96.8 6.5 1.9 5.0 2311400200097 1.0 0.9 0.9974 0.9925 1. 2311400200098 1. 2311400200099 9.15 0.15 162.9 5.7 1.9 4.0 2311400200100 1.0 0.6 1.0731 1.3117 1. 2311400200101 1. 2311400200102 13.33 0.15 241.8 4.6 1.6 2.5 2311400200103 1.0 0.4 0.3 0.9168 0.8288 1. 2311400200104 1. 2311400200105 16.10 0.15 152.4 4.6 2. 2.1 2311400200106 1.0 0.6 0.3 1.0749 1.2335 1. 2311400200107 1. 2311400200108 17.16 0.03 116.1 4.4 2. 1.5 2311400200109 1.0 0.6 0.3 0.9987 0.9878 0.998 2311400200110 0.997 2311400200111 17.90 0.10 105.7 4.4 2.2 1.3 2311400200112 0.7 0.7 0.3 0.969 0.933 0.998 2311400200113 0.997 2311400200114 19.36 0.15 89.5 8.2 3.1 6.3 2311400200115 2.0 0.6 1.3 1.0061 1.0157 0.941 2311400200116 0.926 2311400200117 19.95 0.07 102.1 5.8 4.1 1.4 2311400200118 1.0 0.6 1.4 0.9822 0.9433 0.922 2311400200119 0.891 2311400200120 20.61 0.04 77.9 8.8 5.4 5.7 2311400200121 1.6 0.6 1.4 0.9938 0.982 0.885 2311400200122 0.832 2311400200123 ENDDATA 33 0 2311400200124 ENDSUBENT 123 0 2311400299999 ENDENTRY 2 0 2311499999999