ENTRY 23135 20141209 22412313500000001 SUBENT 23135001 20141209 22412313500100001 BIB 17 142 2313500100002 TITLE Delayed neutron measurements of Th-232 neutron-induced 2313500100003 fission. 2313500100004 AUTHOR (X.Ledoux,D.Dore,M.Mosconi,R.Nolte,S.Roettger,S.Varet) 2313500100005 INSTITUTE (2GERPTB) PTB,38116, Braunschweig. 2313500100006 - M.Mosconi, R.Nolte, S.Roettger, S.Varet . 2313500100007 (2FR BRC) CEA/DAM/DIF, Arpajon. 2313500100008 - X.Ledoux. 2313500100009 (2FR SAC) IRFU/SPhN, CEA/Saclay, 91191 Gif-sur-Yvette. 2313500100010 - D.Dore. 2313500100011 REFERENCE (J,ANE,76,514,2015) Data table. 2313500100012 #doi:10.1016/j.anucene.2014.10.012 2313500100013 (J,EPJ/CS,8,07010,2010) Figure only. Preliminary. 2313500100014 #doi:10.1051/epjconf/20100807010 2313500100015 REL-REF (I,,H.J.Brede+,J,NIM,169,349,1980) 2313500100016 Details of facility. 2313500100017 (I,,R.Nolte+,J,RPD,110,97,2004) 2313500100018 Details of facility. 2313500100019 (R,13700002,G.R.Keepin+,J,PR,107,1044,1957) 2313500100020 Data of G.Keepin+ used in analysis. 2313500100021 (N,,M.Ionescu-Bujor+,J,NSE,147,189,2004) 2313500100022 Error propagation method. 2313500100023 FACILITY (VDG,2GERPTB) Low-Scatter Hall at PTB Ion Accelerator 2313500100024 (CYCLO,2GERPTB) Facility. 2313500100025 3.75MV Van De Graaff accelerator and the cyclotron CV282313500100026 depending on the energy of the neutrons. 2313500100027 INC-SOURCE (P-T,D-D,D-T) H-3(p,n)He-3, H-2(d,n)He-3, H-3(d,n)He-4.2313500100028 The solid-state tritium targets of Ti layer deposited 2313500100029 on a Ag backing - T/Ti ratio about 1.3. 2313500100030 The deuterium gas target of length 30 mm, equipped with2313500100031 Mo entrance foil of 5 micron thickness; deuterium gas 2313500100032 pressure 1-2 bar . 2313500100033 Neutron production parameters : 2313500100034 En Reaction Eproj Target Thickness Pressure Fluence 2313500100035 MeV MeV mg/cm2 Bar 1/s/cm**22313500100036 VdG accelerator: 2313500100037 2 3H(p,n)3He 2.862 Solid 2000 1.02E+6 2313500100038 16 3H(d,n)4He 0.731 Solid 1000 5.60E+5 2313500100039 6 2H(d,n)3He 3.211 Gas 1. 9.09E+5 2313500100040 CV28 accelerator: 2313500100041 3 3H(p,n)3He 3.841 Solid 2000 1.17E+6 2313500100042 4 3H(p,n)3He 4.828 Solid 2000 3.88E+5 2313500100043 7 2H(d,n)3He 4.158 Gas 1.5 4.12E+5 2313500100044 10 2H(d,n)3He 7.135 Gas 2. 7.89E+5 2313500100045 The fluence rate at the sample position . 2313500100046 INC-SPECT Mono-energy neutrons, excluding 10 MeV neutrons - not 2313500100047 purely mono-kinetic neutrons (correction was done to 2313500100048 take into account low energy continuous component at 2313500100049 10 MeV EN). 2313500100050 METHOD (EXTB) 5 min continuous irradiation period to reach the2313500100051 equilibrium, followed by a large number of cycles 2313500100052 composed of irradiation sequences with Tirr=7 s and 2313500100053 counting sequences with Tcounting = 1 s. 2313500100054 DETECTOR (HE3SP) 12 gas detectors filled with He-3 (pressure 2313500100055 4bar)are inserted in hollow cylinder (inner diameter 2313500100056 12 cm, outer diameter = 32 cm, length 37 cm) of 2313500100057 polyethylene. Moderator was covered by 1mm thick Cd. 2313500100058 The detection efficiency to neutrons (between 100 keV 2313500100059 and 1MeV) emitted in Th sample is simulated with the 2313500100060 MCNPX transport code. Since the He-3 pressure in the 2313500100061 tubes being not well known, the results of simulations 2313500100062 had to be normalized to the efficiency for Cf-252 2313500100063 neutron spectrum measured using two calibrated Cf-252 2313500100064 sources (1.521+-0.025)*10**5 1/s and 2313500100065 (3.821+-0.080)*10**3 1/s at different positions. 2313500100066 The global detection efficiency of DN is defined to be 2313500100067 0.092 +- 0.003 ; 2 MeV measurement was performed with a2313500100068 higher electronic threshold resulting to a lower 2313500100069 efficiency 0.0501 +- 0.0011 . 2313500100070 Two detectors were used to determine neutron fluence:2313500100071 (TELES) proton recoil telescope (PRT) placed at 0 deg. 2313500100072 with respect to the ion beam line; 2313500100073 (LONGC) fixed long counter placed around 6m from the 2313500100074 neutron source at 98 degrees with respect to the ion 2313500100075 beam line. 2313500100076 SAMPLE Cylindrical thorium sample (2.55 cm diameter, 3.64 cm 2313500100077 length, mass 182.2+-0.5 g ) was placed inside the 2313500100078 neutron detector at zero degree with respect to the ion2313500100079 beam direction at distance of 75 mm from production 2313500100080 target. 2313500100081 MONITOR (1-H-1(N,EL)1-H-1,,SIG) For neutron fluence. 2313500100082 MONIT-REF (,,3,ENDF/B-V,,1983) from: 2313500100083 (,C.A.Uttley,R,IAEA-TECDOC-227,3,1983) 2313500100084 CORRECTION For scattered neutrons, effect was measured during 2313500100085 runs with and without DN detector in place, correction 2313500100086 factor approximately 7%. 2313500100087 For background. 2313500100088 Three energy domains have been defined corresponding to2313500100089 fissions induced by neutrons coming directly from the 2313500100090 source (mono),neutrons with lower energy (down) and 2313500100091 neutrons with higher energy (up). The relative 2313500100092 contributions to the total number of fissions of the 2313500100093 three energy domains (Table 3 of J,ANE,76,514,2014): 2313500100094 E(MeV) Mono (%) Down (%) Up (%) 2313500100095 2. 98.71 0.79 0.50 2313500100096 3. 94.56 5.10 0.34 2313500100097 4. 92.15 7.63 0.22 2313500100098 6. 94.67 5.19 0.14 2313500100099 7. 97.33 2.60 0.07 2313500100100 10. 89.80 10.19 0.01 2313500100101 16. 93.64 6.36 0.00 2313500100102 Corrections due to the fissions in the "up" and "down" 2313500100103 zones depend on the energy but are in any case (except 2313500100104 at 10 MeV) smaller than 8%. 2313500100105 At 10 MeV incident neutron energy - correction due to 2313500100106 the break-up component and the target thickness - 2313500100107 around 10%. 2313500100108 Correction for finite duration of irradiation (cycle: 2313500100109 6.9sec beam on - 1.1s beam of; number of cycles >100) 2313500100110 - 94% .. 2313500100111 ANALYSIS Number of delayed neutrons at t = 0 (beam-off switching2313500100112 time) is determined by fitting the decay time spectrum 2313500100113 with the function defined in Eq.(1) of ANE,76,514,2015 2313500100114 and the parameters from REL-REF of G.R.Keepen+: 2313500100115 ((90-TH-232(N,F),DL/GRP,NU,,FIS)/ 2313500100116 (90-TH-232(N,F),DL,NU,,FIS)) 2313500100117 Group Ti, sec ai, % 2313500100118 1 56.03+-0.95 3.4+-0.2 2313500100119 2 20.75+-0.66 15.0+-0.5 2313500100120 3 5.74+-0.24 15.5+-2.1 2313500100121 4 2.16+-0.08 44.6+-1.5 2313500100122 5 0.571+-0.042 17.2+-1.3 2313500100123 6 0.211+-0.019 4.3+-0.6 2313500100124 Ti - precursors half-life, 2313500100125 ai - relative yield. 2313500100126 Only the contributions of the groups 4, 5, 6 were 2313500100127 considered to fit the curve since their contribution is2313500100128 predominant. The contribution of the groups 1- is 2313500100129 considered as constant . 2313500100130 Number of fissions in the sample was obtained from the 2313500100131 fluence measurement combined with MCNPX transport code 2313500100132 calculations using a detailed model of the set-up 2313500100133 containing the thorium sample, the DN detector and the 2313500100134 neutron source. Neutron source angular and energy 2313500100135 distributions were calculated with DROSG code 2313500100136 DROSG-2000,IAEA, http://www-nds.iaea.org/drosg2000.html2313500100137 COMMENT This work was supported by the EURATOM 6 Framework 2313500100138 Programme 'European Facilities for Nuclear Data 2313500100139 Measurements' (EFNUDAT). 2313500100140 HISTORY (20110721C) M.M. 2313500100141 (20141208A) M.M. Ref. J,ANE,76,514,2015 was added. 2313500100142 BIB information was updated. 2313500100143 Data were added in Subent 002. 2313500100144 ENDBIB 142 0 2313500100145 NOCOMMON 0 0 2313500100146 ENDSUBENT 145 0 2313500199999 SUBENT 23135002 20141209 22412313500200001 BIB 6 71 2313500200002 REACTION (90-TH-232(N,F),DL,NU) 2313500200003 REL-REF (A,13700020,G.R.Keepin+,J,PR,107,1044,195708) 2313500200004 (A,12288001,C.F.Masters+,J,NSE,36,202,1969) 2313500200005 (A,22571002,M.Herrmann+,C,67VIENNA,,147,196703) 2313500200006 (A,23038002,V.Macary+,T,MACARY,2008) 2313500200007 Data are in quite good agreement with published data 2313500200008 between 2 MeV and 3 MeV and are a little bit higher at 2313500200009 16 MeV. 2313500200010 ENDF and the JENDL library underestimate this data at 2313500200011 low energy but are in good agreement for energy greater2313500200012 than 6 MeV. 2313500200013 ERR-ANALYS (ERR-T) Total uncertainty was defined by correlation 2313500200014 factors and sensitivity factors using the error 2313500200015 propagation method of Ionescu-Bujor and Cacuci,2004, 2313500200016 see REL-REF of Subent 001. 2313500200017 The relative uncertainties of the 10 parameters (%): 2313500200018 Fdet EPS m Fdir K NUd NUu N-mono N-u N-d 2313500200019 2. 3.3 0.5 2.2-4.0 1. 10. 10. 3. 10. 10. 2313500200020 (ERR-1) Fdet - DN detection rate - 2.%, 2313500200021 (ERR-2) EPS - detection efficiency - 3.3%, 2313500200022 (ERR-3) m - mass of Th sample - 0.5%, 2313500200023 (ERR-4,2.2,4.0) Fdir - fluence rate measured at 0 deg 2313500200024 - 2.2-4.0, 2313500200025 (ERR-5) K - ratio of total c-s of neutron production 2313500200026 reaction DROSG-2000 to differential cross-section at 2313500200027 0 deg of neutron production reaction - 1.%, 2313500200028 (ERR-6) NUd, -10.%, 2313500200029 (ERR-7) NUu - 10.% 2313500200030 -absolute DNs yield averaged over the energy regions 2313500200031 'up' ( index u ) and 'down' (index d), respectively; 2313500200032 (ERR-8) N-mono, - 3.%, 2313500200033 (ERR-9) N-u, - 10.%, 2313500200034 (ERR-10) N-d - 10.% 2313500200035 - calculated fission energy distributions per neutron2313500200036 source in the energy regions 'mono', 'up' (index u) and2313500200037 'down' (index d), respectively. 2313500200038 Sensitivity factors Si,k (i=1-8 measurement number, 2313500200039 k=1-10 parameter number): 2313500200040 En,MeV Fdet EPS m Fdir NUd NUu 2313500200041 1.996 1.0105 -1.0105 -1.0105 -1.0105 -0.0037 -0.0068 2313500200042 2.974 1.0503 -1.0503 -1.0503 -1.0503 -0.0025 -0.0478 2313500200043 3.999 1.0767 -1.0767 -1.0767 -1.0767 -0.0015 -0.0751 2313500200044 3.999 1.0745 -1.0745 -1.0745 -1.0745 -0.0015 -0.0730 2313500200045 5.997 1.0704 -1.0704 -1.0704 -1.0704 -0.0012 -0.0692 2313500200046 6.967 1.0397 -1.0397 -1.0397 -1.0397 -0.0007 -0.0389 2313500200047 10.024 1.1852 -1.1852 -1.1852 -1.1852 -0.0001 -0.1850 2313500200048 15.936 1.1054 -1.1054 -1.1054 -1.1054 0.0000 -0.1054 2313500200049 En,MeV N-mono N-u N-d K 2313500200050 1.996 -1.0000 -0.0037 -0.0068 -1.0105 2313500200051 2.974 -1.0000 -0.0025 -0.0478 -1.0503 2313500200052 3.999 -1.0000 -0.0015 -0.0751 -1.0767 2313500200053 3.999 -1.0000 -0.0015 -0.0730 -1.0745 2313500200054 5.997 -1.0000 -0.0012 -0.0692 -1.0704 2313500200055 6.967 -1.0000 -0.0007 -0.0389 -1.0397 2313500200056 10.024 -1.0000 -0.0001 -0.1850 -1.1852 2313500200057 15.936 -1.0000 0.0000 -0.1054 -1.1054 2313500200058 MISC-COL (MISC) Absolute total uncertainty. 2313500200059 COVARIANCE Correlation coefficients matrix: 2313500200060 (XY,8,EN,MEV) 2313500200061 1.996 2.974 3.999 3.999 5.997 6.967 10.024 15.936 2313500200062 (Z,36,COR,NO-DIM) 2313500200063 1.00 0.21 0.22 0.22 0.22 0.22 0.18 0.21 2313500200064 1.00 0.30 0.30 0.30 0.31 0.25 0.29 2313500200065 1.00 0.61 0.31 0.32 0.26 0.30 2313500200066 1.00 0.31 0.32 0.26 0.30 2313500200067 1.00 0.32 0.25 0.29 2313500200068 1.00 0.26 0.30 2313500200069 1.00 0.24 2313500200070 1.00 2313500200071 STATUS (TABLE) Table 4 of J,ANE,76,514,2015 . 2313500200072 Prelim.data are on Fig.3 of J,EPJ/CS,8,07010,2010 2313500200073 ENDBIB 71 0 2313500200074 COMMON 9 6 2313500200075 ERR-1 ERR-2 ERR-3 ERR-5 ERR-6 ERR-7 2313500200076 ERR-8 ERR-9 ERR-10 2313500200077 PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT 2313500200078 PER-CENT PER-CENT PER-CENT 2313500200079 2. 3.3 0.5 1. 10. 10. 2313500200080 3. 10. 10. 2313500200081 ENDCOMMON 6 0 2313500200082 DATA 5 8 2313500200083 EN EN-ERR DATA ERR-T MISC 2313500200084 MEV PER-CENT PC/FIS PER-CENT PC/FIS 2313500200085 1.996 7.5 5.92 5.9 0.35 2313500200086 2.974 4.1 5.65 6.3 0.35 2313500200087 3.999 2.6 5.49 6.2 0.34 2313500200088 3.999 5.64 6.2 0.35 2313500200089 5.997 2.2 3.59 6.3 0.23 2313500200090 6.967 2.1 3.10 5.9 0.18 2313500200091 10.024 1.2 2.92 8.5 0.25 2313500200092 15.936 3.6 2.58 6.8 0.17 2313500200093 ENDDATA 10 0 2313500200094 ENDSUBENT 93 0 2313500299999 ENDENTRY 2 0 2313599999999