ENTRY 14830 20240806 1483000000001 SUBENT 14830001 20240806 20250110 1483000100001 BIB 12 53 1483000100002 TITLE New constraint on the 237Np(n,gamma)238Np integral 1483000100003 cross section using the Godiva-IV critical assembly 1483000100004 AUTHOR (A.S.Tamashiro,S.Burcher,J.T.Harke,B.Pierson, 1483000100005 J.G.Duarte,Y.Mishnayot,S.W.Padgett,P.Zhao, 1483000100006 N.Gharibyan,J.Goda,L.Greenwood,D.Hayes,J.Hutchinson, 1483000100007 N.Harward,K.Roberts,G.Slavik,J.Walker) 1483000100008 REFERENCE (J,PR/C,110,014626,2024) 1483000100009 #doi:10.1103/PhysRevC.110.014626 1483000100010 INSTITUTE (1USALRL,1USABNW,1USALAS) 1483000100011 FACILITY (CRASS,1USALAS) Within the Device Assembly Facility 1483000100012 (DAF) at the Nevada National Security Site (NNSS), 1483000100013 this work utilized the Godiva-IV critical assembly 1483000100014 operated by Los Alamos National Laboratory (LANL) as 1483000100015 part of the National Criticality Experiments Research 1483000100016 Center (NCERC). Godiva IV is an unreflected highly 1483000100017 enriched uranium (HEU) critical assembly. It is a 1483000100018 nominal 6 in. tall, 7 in. diameter cylinder with an 1483000100019 internal cavity 0.55 in. in diameter that extends 1483000100020 half way through the core used to expose experimental 1483000100021 samples to a high neutron flux. 1483000100022 INC-SPECT The Godiva-IV neutron spectrum is not the pure 235U 1483000100023 fission spectrum but a slightly degraded spectrum due 1483000100024 to neutron down-scatter. For this experiment 1483000100025 Godiva-IV was operated above super prompt critical to 1483000100026 generate a large burst of neutrons nearly 1483000100027 simultaneously. The total neutron fluence during the 1483000100028 burst was determined to be Flux = 2.86(7) x10**14 1483000100029 neutrons/cm2 using STAYSL. The flux-weighted mean 1483000100030 neutron energy observed by the target was 1.34 MeV. 1483000100031 DETECTOR (HPGE) Two broad-energy germanium (BEGe) detectors 1483000100032 (Canberra, model BE6530) mounted on large liquid 1483000100033 nitrogen dewars. 1483000100034 SAMPLE A total of four 237Np-nitrate samples were prepared 1483000100035 at Lawrence Livermore National Laboratory (LLNL). 1483000100036 The four samples contain masses of 237Np ranging from 1483000100037 6.0(1) to 44.5(4) mg. The mass of 237Np in the 1483000100038 samples was determined by the activity prior to 1483000100039 irradiation, as measured via gamma-ray spectroscopy. 1483000100040 METHOD (ACTIV) The neptunium samples and a witness foil pack 1483000100041 were irradiated in the Godiva-IV critical assembly on 1483000100042 January 22, 2020. Samples are loaded into a thin 1483000100043 aluminum tube that is inserted into the center 1483000100044 cavity. Following the irradiation, the samples placed 1483000100045 in a gamma-ray counting setup and the gamma rays 1483000100046 emitted from the decay of 238Np were measured over a 1483000100047 time period of approximately 7 d. Multiple gamma-ray 1483000100048 decay branches of 238Np were observed. 1483000100049 CORRECTION The observed activity from each gamma ray requires an 1483000100050 energy dependent correction for the attenuation of 1483000100051 intensity due to shielding from the sample itself, 1483000100052 referred to as self attenuation. 1483000100053 HISTORY (20240806C) BP 1483000100054 STATUS (APRVD) Approved by A.S.Tamashiro on August 28, 2024. 1483000100055 ENDBIB 53 0 1483000100056 COMMON 1 3 1483000100057 EN-DUMMY 1483000100058 MEV 1483000100059 1.34 1483000100060 ENDCOMMON 3 0 1483000100061 ENDSUBENT 60 0 1483000199999 SUBENT 14830002 20240806 20250110 1483000200001 BIB 4 15 1483000200002 REACTION (93-NP-237(N,G)93-NP-238,,SIG,,FIS) 1483000200003 ERR-ANALYS (DATA-ERR) The uncertainty for the measured integral 1483000200004 cross sections were calculated using error 1483000200005 propagation while preserving the correlations of the 1483000200006 parameters. 1483000200007 DECAY-DATA (93-NP-238,50.31HR,DG,882.7,0.00802, 1483000200008 DG,924.1,0.026634, 1483000200009 DG,936.7,0.00360, 1483000200010 DG,941.5,0.00498, 1483000200011 DG,962.9,0.00644, 1483000200012 DG,984.6,0.252, 1483000200013 DG,1026.,0.0875, 1483000200014 DG,1028.6,0.1823) 1483000200015 STATUS (TABLE,,A.S.Tamashiro+,J,PR/C,110,014626,2024) 1483000200016 TABLE V, page 014626-8 of J,PR/C,110,014626,2024. 1483000200017 ENDBIB 15 0 1483000200018 NOCOMMON 0 0 1483000200019 DATA 2 1 1483000200020 DATA DATA-ERR 1483000200021 MB MB 1483000200022 342.0 11.0 1483000200023 ENDDATA 3 0 1483000200024 ENDSUBENT 23 0 1483000299999 SUBENT 14830003 20240806 20250110 1483000300001 BIB 2 109 1483000300002 SUPPL-INF (INCSP) The group-wise neutron fluence used in the 1483000300003 calculations. 1483000300004 -------------------------------------------- 1483000300005 Group # En (MeV) En (MeV) Flux(n/cm2) 1483000300006 -------------------------------------------- 1483000300007 1 1.00E-10 1.00E-9 1.941E-07 1483000300008 2 1.00E-9 1.00E-8 1.941E-07 1483000300009 3 1.00E-8 2.30E-8 1.942E-07 1483000300010 4 2.30E-8 5.00E-8 1.943E-07 1483000300011 5 5.00E-8 7.60E-8 1.945E-07 1483000300012 6 7.60E-8 1.15E-7 1.947E-07 1483000300013 7 1.15E-7 1.70E-7 1.950E-07 1483000300014 8 1.70E-7 2.55E-7 1.954E-07 1483000300015 9 2.55E-7 3.80E-7 1.958E-07 1483000300016 10 3.80E-7 5.50E-7 1.963E-07 1483000300017 11 5.50E-7 8.40E-7 1.969E-07 1483000300018 12 8.40E-7 1.28E-6 1.975E-07 1483000300019 13 1.28E-6 1.90E-6 1.981E-07 1483000300020 14 1.90E-6 2.80E-6 1.988E-07 1483000300021 15 2.80E-6 4.25E-6 2.790E+07 1483000300022 16 4.25E-6 6.30E-6 2.002E-07 1483000300023 17 6.30E-6 9.20E-6 2.009E-07 1483000300024 18 9.20E-6 1.35E-5 1.081E+08 1483000300025 19 1.35E-5 2.10E-5 2.021E-07 1483000300026 20 2.10E-5 3.00E-5 9.383E+06 1483000300027 21 3.00E-5 4.50E-5 2.029E-07 1483000300028 22 4.50E-5 6.90E-5 2.031E-07 1483000300029 23 6.90E-5 1.00E-4 2.031E-07 1483000300030 24 1.00E-4 1.35E-4 2.232E+07 1483000300031 25 1.35E-4 1.70E-4 6.674E+07 1483000300032 26 1.70E-4 2.20E-4 3.533E+07 1483000300033 27 2.20E-4 2.80E-4 3.059E+08 1483000300034 28 2.80E-4 3.60E-4 2.693E+08 1483000300035 29 3.60E-4 4.50E-4 1.565E+08 1483000300036 30 4.50E-4 5.75E-4 5.612E+08 1483000300037 31 5.75E-4 7.60E-4 8.967E+08 1483000300038 32 7.60E-4 9.60E-4 1.786E+09 1483000300039 33 9.60E-4 1.28E-3 3.035E+09 1483000300040 34 1.28E-3 1.60E-3 2.890E+09 1483000300041 35 1.60E-3 2.00E-3 2.882E+09 1483000300042 36 2.00E-3 2.70E-3 7.211E+09 1483000300043 37 2.70E-3 3.40E-3 9.592E+09 1483000300044 38 3.40E-3 4.50E-3 1.875E+10 1483000300045 39 4.50E-3 5.50E-3 2.172E+10 1483000300046 40 5.50E-3 7.20E-3 4.831E+10 1483000300047 41 7.20E-3 9.20E-3 6.604E+10 1483000300048 42 9.20E-3 1.20E-2 1.259E+11 1483000300049 43 1.20E-2 1.50E-2 1.534E+11 1483000300050 44 1.50E-2 1.90E-2 2.315E+11 1483000300051 45 1.90E-2 2.55E-2 5.254E+11 1483000300052 46 2.55E-2 3.20E-2 5.789E+11 1483000300053 47 3.20E-2 4.00E-2 8.561E+11 1483000300054 48 4.00E-2 5.25E-2 1.606E+12 1483000300055 49 5.25E-2 6.60E-2 1.962E+12 1483000300056 50 6.60E-2 8.80E-2 3.810E+12 1483000300057 51 8.80E-2 1.10E-1 4.143E+12 1483000300058 52 1.10E-1 1.35E-1 5.281E+12 1483000300059 53 1.35E-1 1.60E-1 5.317E+12 1483000300060 54 1.60E-1 1.90E-1 6.787E+12 1483000300061 55 1.90E-1 2.20E-1 6.594E+12 1483000300062 56 2.20E-1 2.55E-1 7.589E+12 1483000300063 57 2.55E-1 2.90E-1 7.480E+12 1483000300064 58 2.90E-1 3.20E-1 6.411E+12 1483000300065 59 3.20E-1 3.60E-1 8.249E+12 1483000300066 60 3.60E-1 4.00E-1 8.008E+12 1483000300067 61 4.00E-1 4.50E-1 9.315E+12 1483000300068 62 4.50E-1 5.00E-1 8.973E+12 1483000300069 63 5.00E-1 5.50E-1 8.472E+12 1483000300070 64 5.50E-1 6.00E-1 8.071E+12 1483000300071 65 6.00E-1 6.60E-1 9.046E+12 1483000300072 66 6.60E-1 7.20E-1 8.386E+12 1483000300073 67 7.20E-1 7.80E-1 7.657E+12 1483000300074 68 7.80E-1 8.40E-1 7.082E+12 1483000300075 69 8.40E-1 9.20E-1 8.583E+12 1483000300076 70 9.20E-1 1.00E+00 7.907E+12 1483000300077 71 1.00E+00 1.20E+00 1.718E+13 1483000300078 72 1.20E+00 1.40E+00 1.431E+13 1483000300079 73 1.40E+00 1.60E+00 1.218E+13 1483000300080 74 1.60E+00 1.80E+00 1.055E+13 1483000300081 75 1.80E+00 2.00E+00 9.087E+12 1483000300082 76 2.00E+00 2.30E+00 1.157E+13 1483000300083 77 2.30E+00 2.60E+00 9.531E+12 1483000300084 78 2.60E+00 2.90E+00 7.845E+12 1483000300085 79 2.90E+00 3.30E+00 8.302E+12 1483000300086 80 3.30E+00 3.70E+00 6.357E+12 1483000300087 81 3.70E+00 4.10E+00 4.857E+12 1483000300088 82 4.10E+00 4.50E+00 3.698E+12 1483000300089 83 4.50E+00 5.00E+00 3.409E+12 1483000300090 84 5.00E+00 5.50E+00 2.429E+12 1483000300091 85 5.50E+00 6.00E+00 1.712E+12 1483000300092 86 6.00E+00 6.70E+00 1.579E+12 1483000300093 87 6.70E+00 7.40E+00 9.449E+11 1483000300094 88 7.40E+00 8.20E+00 6.337E+11 1483000300095 89 8.20E+00 9.00E+00 3.559E+11 1483000300096 90 9.00E+00 1.00E+01 2.383E+11 1483000300097 91 1.00E+01 1.10E+01 1.178E+11 1483000300098 92 1.10E+01 1.20E+01 5.730E+10 1483000300099 93 1.20E+01 1.30E+01 2.767E+10 1483000300100 94 1.30E+01 1.40E+01 1.300E+10 1483000300101 95 1.40E+01 1.50E+01 5.626E+09 1483000300102 96 1.50E+01 1.60E+01 3.139E+09 1483000300103 97 1.60E+01 1.70E+01 1.336E+09 1483000300104 98 1.70E+01 1.80E+01 4.843E+08 1483000300105 99 1.80E+01 1.90E+01 4.707E+08 1483000300106 100 1.90E+01 2.00E+01 1.094E+08 1483000300107 -------------------------------------------- 1483000300108 STATUS (TABLE,,A.S.Tamashiro+,J,PR/C,110,014626,2024) 1483000300109 TABLE VII, page 014626-14 - 014626-15 of 1483000300110 J,PR/C,110,014626,2024. 1483000300111 ENDBIB 109 0 1483000300112 NOCOMMON 0 0 1483000300113 NODATA 0 0 1483000300114 ENDSUBENT 113 0 1483000399999 ENDENTRY 3 0 1483099999999