ENTRY 23334 20170410 22592333400000001 SUBENT 23334001 20170410 22592333400100001 BIB 12 63 2333400100002 TITLE Absolute cross section measurements of neutron-induced 2333400100003 fission of 242Pu from 1 to 2.5 MeV . 2333400100004 AUTHOR (C.Matei, F.Belloni,J.Heyse, A.J.M.Plompen, D.J.Thomas)2333400100005 INSTITUTE (2UK NPL) C.Matei, D.J.Thomas 2333400100006 (3RUMBUC) Horia Hulubei National Institute for RandD in2333400100007 Physics and Nuclear Engineering,Bucharest-Magurele 2333400100008 077125, Romania . C.Matei, 2333400100009 (2ZZZGEL) F.Belloni, J.Heyse, A.J.M.Plompen 2333400100010 REFERENCE (J,PR/C,95,024606,2017) 2333400100011 #doi:10.1103/PhysRevC.95.024606 2333400100012 REL-REF (M,,R.Nolte+,J,MET,48,S274,2011) 2333400100013 Neutron fluence measurement procedure. 2333400100014 FACILITY (VDG,2UK NPL) 3.5 MV Van de Graaff accelerator . 2333400100015 JRC-Geel data acquisition system DAQ2000. 2333400100016 INC-SOURCE (P-T) for neutrons of 1. - 3. MeV. 2333400100017 Target - layer of 1000 microg/cm2 Ti(T) of 2.54-cm 2333400100018 diameter evaporated on a 0.5 mm gold backing disk. 2333400100019 DETECTOR (LONGC) The neutron fluence is measured using either 2333400100020 the NPL standard Long Counter, or the DePangher 2333400100021 precision long counter. 2333400100022 (IOCH) An ionization chamber with back-to-back 238U and2333400100023 242Pu targets. The counting gas - P-10 (90% Ar + 10% 2333400100024 CH4) continuously flowing at a rate of ~50 ml/min, 2333400100025 pressure 1.020 bar. 2333400100026 SAMPLE Pu-242 sample : 2333400100027 Production method Molecular plating 2333400100028 Chemical composition Pu(OH)4 2333400100029 Diameter (mm) 29.95 +- 0.03 2333400100030 Activity (MBq) 0.0915 +- 0.0003 2333400100031 Mass (microg) 625 +- 5 2333400100032 Areal density (microg/cm2) 88.7 +- 0.8 2333400100033 Isotopic purity 99.96518(45)% 2333400100034 The mass and areal density were deduced using the 2333400100035 242Pu alpha half-life 3.73E+5 yr. 2333400100036 The isotopic composition was measured by mass 2333400100037 spectroscopy. 2333400100038 239Pu, 241Pu, and 244Pu contribute < 0.06% to the 2333400100039 activity. 2333400100040 Distance neutron source - IOCH front wall was 44-50 mm2333400100041 with a 0.5 mm uncertainty. 2333400100042 The activity of the Pu deposit was measured to be 2333400100043 0.0915 +- 0.0003 MBq on April 7, 2011. 2333400100044 The mass of the deposit 0.625 +- 0.005 mg was 2333400100045 calculated from the activity measurement. 2333400100046 The isotopic composition was determined by mass 2333400100047 spectroscopy on May 12, 2011. 2333400100048 There was insignificant loss of 242Pu, 0.0003%, due to2333400100049 alpha decay in the time from activity measurement to 2333400100050 the experiment date. 2333400100051 METHOD (FISCT) 2333400100052 ADD-RES (DECAY) Pu-242 spontaneous fission half -life was 2333400100053 measured to be (6.72+-0.09stat.)*10**10 yr; 2333400100054 systematic uncertainties : 2333400100055 the measured alpha activity with 0.3%, 2333400100056 the 242Pu alpha half-life with 0.8%, 2333400100057 the detection efficiency with 1%, 2333400100058 the fitting procedure with 0.5%; 2333400100059 from the experimentally determined branching ratio 2333400100060 Asf / Aalpha = 5.55*10**6, which has a relative 2333400100061 uncertainty of only 1%. 2333400100062 HISTORY (20170410C) M.M. 2333400100063 Request for the data was sent 12.04.2017 . 2333400100064 (20170419R) Data were received 19.04.2017 from C.Matei 2333400100065 ENDBIB 63 0 2333400100066 NOCOMMON 0 0 2333400100067 ENDSUBENT 66 0 2333400199999 SUBENT 23334002 20170410 22592333400200001 BIB 8 42 2333400200002 REACTION (94-PU-242(N,F),,SIG) 2333400200003 REL-REF (A,,F.Tovesson+,J,PR/C,79,014613,2009) Consistent 2333400200004 (A,,H.Weigmann+,J,NP/A,438,333,1985) 2333400200005 Agree at En 1.2 MeV and higher 2333400200006 (D,,P.Salvador-Castineira+,J,PR/C,92,044606,2015) 2333400200007 Agree at 2 and 2.5 MeV, but three lowest points are 2333400200008 above results of Salvador-Castineira+ 2333400200009 (A,,D.W.Bergen+,J,NP/A,163,577,1971) 2333400200010 (D,,G.F.Auchampaugh+,J,NP/A,171,31,1971) 2333400200011 At 2 MeV the data of G.Auchampaugh lower . 2333400200012 MONITOR The current integrator system which measures the 2333400200013 charged particle beam current on the neutron producing 2333400200014 target, was used as monitoring device at neutron 2333400200015 fluence measurement. 2333400200016 ANALYSIS Fission cross section SIG was defined: 2333400200017 SIG=R(En)/(N*F(En)), where 2333400200018 N - the number of 242Pu nuclei in the sample, 2333400200019 F(En) - the neutron fluence, 2333400200020 R(En)=(Y(En)-Ysf)/EPS(En), where 2333400200021 Y(En) - the observed number of counts, 2333400200022 Ysf - counts due to spontaneous fission, 2333400200023 EPS(Evn) - the detection efficiency. 2333400200024 The derivation of the neutron fluence was performed 2333400200025 with the use of a dedicated NPL computer program FLUCAL2333400200026 CORRECTION For multiple scattering. 2333400200027 For neutron beam attenuation. 2333400200028 For spontaneous fission. 2333400200029 MISC-COL (MISC1) Neutron fluence,10**9/cm2; 2333400200030 uncertainties of fluence- see ERR-1 . 2333400200031 (MISC2) Target scattering correction,% 2333400200032 (MISC3) Beam attenuation correction,% 2333400200033 ERR-ANALYS (ERR-S) Statistical uncertainty 2333400200034 (ERR-1) Fluence standard uncertainty 2333400200035 (ERR-2) Pu-242 alpha half-life uncertainty 2333400200036 (ERR-3) Sample activity 2333400200037 (ERR-4) Efficiency 2333400200038 (ERR-5) Multiple scattering 2333400200039 (ERR-6) Fitting procedure 2333400200040 (ERR-SYS,2.9,3.8) Total systematic uncertainty 2333400200041 (ERR-T) Total uncertainty 2333400200042 STATUS (TABLE) Data were received 19.04.2017 from C.Matei 2333400200043 Data are on Fig.3 of J,PR/C,95,024606,2017 2333400200044 ENDBIB 42 0 2333400200045 COMMON 6 3 2333400200046 ERR-S ERR-2 ERR-3 ERR-4 ERR-5 ERR-6 2333400200047 PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT 2333400200048 0.8 0.8 0.3 0.5 0.5 0.5 2333400200049 ENDCOMMON 3 0 2333400200050 DATA 7 5 2333400200051 EN DATA ERR-T ERR-1 MISC1 MISC2 2333400200052 MISC3 2333400200053 MEV B B PER-CENT SEE TEXT PER-CENT 2333400200054 PER-CENT 2333400200055 1.000 1.423 0.053 3.3 2.56 2.9 2333400200056 96.8 2333400200057 1.100 1.499 0.043 2.5 2.81 2.9 2333400200058 96.8 2333400200059 1.200 1.550 0.059 3.4 2.10 3.0 2333400200060 96.8 2333400200061 2.000 1.453 0.055 3.4 4.95 1.8 2333400200062 97.1 2333400200063 2.500 1.450 0.055 3.4 4.02 1.5 2333400200064 97.1 2333400200065 ENDDATA 14 0 2333400200066 ENDSUBENT 65 0 2333400299999 ENDENTRY 2 0 2333499999999