ENTRY 23165 20120817 22332316500000001 SUBENT 23165001 20120817 22332316500100001 BIB 15 98 2316500100002 TITLE Indirect (n,gamma) cross sections of thorium cycle 2316500100003 nuclei using the surrogate method. 2316500100004 AUTHOR (J.N.Wilson, F.Gunsing, L.A.Bernstein, A.Buerger, 2316500100005 A.Goergen, M.Guttormsen, A.-C.Larsen, P.Mansouri, 2316500100006 T.Renstroem, S.J.Rose, A.Semchenkov, S.Siem,N.U.H.Syed,2316500100007 H.K.Toft, M.Wiedeking, T.Wiborg-Hagen) 2316500100008 INSTITUTE (2FR PAR) J.N.Wilson. 2316500100009 Institut de Physique Nucleaire d'Orsay, Bat.100, 15 rue2316500100010 G.Clemenceau, 91406 Orsay cedex, France. 2316500100011 (2FR SAC) F.Gunsing,A.Goergen. 2316500100012 (2NOROSL) A.Buerger,A.Goergen,M.Guttormsen,A.-C.Larsen,2316500100013 P.Mansouri,T.Renstroem, S.J.Rose, A.Semchenkov, S.Siem,2316500100014 N.U.H.Syed,H.K.Toft,T.Wiborg-Hagen. 2316500100015 (1USALRL) L.A.Bernstein,M.Wiedeking. 2316500100016 (3SAFITH) M.Wiedeking. 2316500100017 REFERENCE (J,PR/C,85,034607,2012) Graphs for Th, Pa c-s. 2316500100018 #doi:10.1103/PhysRevC.85.034607 2316500100019 (J,EPJ/CS,21,01003,2012) Graph for Th-232 c-s. 2316500100020 #doi:10.1051/epjconf/20122101003 2316500100021 REL-REF (M,,J.N.Wilson+,J,NIM/A,511,388,2003) 2316500100022 #doi:10.1016/S0168-9002(03)01944-2 2316500100023 Weighting function technique. 2316500100024 (M,,A.Borella+,J,NIM/A,577,626,2007) 2316500100025 Weighting function technique. 2316500100026 FACILITY (CYCLO,2NOROSL) Oslo Cyclotron Laboratory using the 2316500100027 CACTUS and Silicon Ring detectors. 2316500100028 INC-SOURCE Beams of deuterium and 3He at bombarding energies of 12316500100029 2 and 24 MeV, respectively. 2316500100030 SAMPLE 968 microg/cm2 target of 232Th. 2316500100031 METHOD (EDE) 2316500100032 (COINC) All coincidence events involving at least one 2316500100033 dE strip and at least one E detector were written to 2316500100034 disk along with any coincident gamma-ray data, if 2316500100035 present. During the 2 weeks of beam time (about 1 week 2316500100036 for d at 0.7 nA and 1 week for 3He at 0.4 nA) a total 2316500100037 of 351E+6 and 135E+6 dE-E coincidence events for d, and2316500100038 3He beams, respectively, were recorded. 2316500100039 The final nucleus decay probabilities were measured 2316500100040 using the weighting function technique. 2316500100041 PART-DET (G) Gammas and LCP 2316500100042 DETECTOR (SPEC,NAICR) CACTUS spectrometer -48 array of 28 2316500100043 high-efficiency lead-collimated NaI detectors arranged 2316500100044 in a spherical geometry.The total detection efficiency 2316500100045 of CACTUS is approximately 15% with each cylindrical 2316500100046 NaI detector of diameter 12.35 cm and 12.35 cm length, 2316500100047 the front face being situated 22 cm from the central 2316500100048 target position. For gamma-ray detection. 2316500100049 The response matrix for the CACTUS array was found by 2316500100050 performing detailed MCNP5 simulations of the CACTUS 2316500100051 detectors, the Pb collimators, the target and frame, 2316500100052 the vacuum chamber, and the detector casings for many 2316500100053 different energies and then interpolating between them.2316500100054 The response was broadened with a broadening function 2316500100055 to provide the correct NaI detector resolution. 2316500100056 (COIN,SI,SI) Silicon Ring detector- for LCP emitted 2316500100057 at backward angles from the beam direction. 2316500100058 Consist of ring of eight wedge-shaped detector modules,2316500100059 each with eight arced dE strips of 130 microm thickness2316500100060 placed in front of a single E detector of 1550 microm 2316500100061 thickness. The eight annular rings of the silicon 2316500100062 detectors were at angles of 124 deg for the outermost 2316500100063 ring and 138 deg for the innermost, giving an angular 2316500100064 resolution for charged-particle detection of slightly 2316500100065 less than 2 deg. The total solid angle covered by the 2316500100066 Silicon Ring was approximately 12% of 4PI sr. 2316500100067 An aluminum absorber of thickness 10.5 microm was 2316500100068 placed in front of the silicon detectors to block 2316500100069 electrons. 2316500100070 The energy resolution for detection of LCP assuming a 2316500100071 2-mm beam spot size was 80 keV. 2316500100072 For the (d,p) channel the best calibration coefficients2316500100073 were obtained by using the elastic scattering peaks on 2316500100074 232Th(d,d') and 16O(d,d'), a target contaminant. For 2316500100075 the (3He,a) and (3He,t) channels the silicon detector 2316500100076 calibration coefficients were obtained from elastic 2316500100077 scattering peak of 232Th(3He,3He') and the position of 2316500100078 the 232Th(3He,a)231Th* ground state. 2316500100079 CORRECTION For the energy losses in the target, aluminum absorber,2316500100080 and the kinematics of the reaction. 2316500100081 For backgrounds. 2316500100082 For (n, n') events. 2316500100083 For target contaminants, frequently 16O and 12C. 2316500100084 For deuterium breakup. 2316500100085 ERR-ANALYS Systematic uncertainties in the measurement technique 2316500100086 due to effect of imperfect weighting functions owing 2316500100087 to the presence of gamma-detection thresholds and the 2316500100088 fact that the detectors do not have isolated hit 2316500100089 probability of 100% were estimated 2316500100090 -of the order 2% for relative (when comparing one 2316500100091 cross section with another) and 2316500100092 - 5% in the absolute value. 2316500100093 COMMENT This work was supported by the CNRS energy program 2316500100094 PACEN (GEDEPEON), the Norwegian Research Council, and 2316500100095 the US Department of Energy under Contract No. 2316500100096 DE-AC52-07NA27344. 2316500100097 HISTORY (20120817C) M.M. 2316500100098 Request for the data was sent to Jon Wilson 17.08.2012.2316500100099 Reply 20.08.2012 -promised to send after 10 Sept.2012.2316500100100 ENDBIB 98 0 2316500100101 NOCOMMON 0 0 2316500100102 ENDSUBENT 101 0 2316500199999 SUBENT 23165002 20120817 22332316500200001 BIB 5 39 2316500200002 REACTION (90-TH-232(N,G)90-TH-233,,SIG,,,DERIV) 2316500200003 REL-REF (O,22931002,G.Aerts+,J,PR/C,73,054610,2006) 2316500200004 In the range 500 keV-1 MeV there is very good agreement2316500200005 with variations typically of the order of 15%. 2316500200006 Above 1 MeV the fission cross section begins to 2316500200007 increase and because we are unable to distinguish 2316500200008 events in which fission occurs, fission gamma rays will2316500200009 begin to contaminate our spectra. 2316500200010 Above 1 MeV the surrogate data increasingly 2316500200011 overestimate the ENDFB7 database values. 2316500200012 The major discrepancy between our measurements and 2316500200013 ENDFB7 occur in the range 0-500 keV, where there is a 2316500200014 large and increasing disagreement toward low energy as 2316500200015 high as 400%. 2316500200016 This discrepancy probably occurs for two reasons: 2316500200017 1) the mismatch in spin distributions between the 2316500200018 indirect and direct reactions leading to an 2316500200019 overestimation of the cross section because decay of 2316500200020 higher final nuclear l waves favors decay by gamma 2316500200021 emission; 2316500200022 2) the finite resolution of silicon detectors smooths 2316500200023 out the step function at the neutron binding energy 2316500200024 that we are attempting to measure and thus the measured2316500200025 decay probabilities are the most incorrect in this 2316500200026 region where the decay probability is varying extremely2316500200027 rapidly. 2316500200028 ANALYSIS (SURGT) Radiative capture c-s deduced via the product 2316500200029 of measured gamma emission probability using the 2316500200030 transfer reaction Th-232(d,p)Th-233 . 2316500200031 The compound nucleus formation cross section was 2316500200032 obtained from TALYS optical model calculations with 2316500200033 input parameters adjusted to accurately reproduce the 2316500200034 experimental total cross sections. 2316500200035 COMMENT Of compiler M.M. In title of Fig.9 in PR/C,85,034607 2316500200036 there is misprint in transfer reaction: 2316500200037 Th-233(d,p) instead of Th-232(d,p) . 2316500200038 STATUS (UNOBT) 2316500200039 Fig.9 of J,PR/C,85,034607,2012. 2316500200040 Fig.3 of J,EPJ/CS,21,01003,2012 2316500200041 ENDBIB 39 0 2316500200042 NOCOMMON 0 0 2316500200043 NODATA 0 0 2316500200044 ENDSUBENT 43 0 2316500299999 SUBENT 23165003 20120817 22332316500300001 BIB 4 12 2316500300002 REACTION (90-TH-230(N,G)90-TH-231,PAR,SIG,,,DERIV) 2316500300003 ANALYSIS (SURGT) Radiative capture c-s deduced via the product 2316500300004 of measured gamma emission probability using the 2316500300005 transfer reaction Th-232(He3,A)Th-231 . 2316500300006 The compound nucleus formation cross section was 2316500300007 obtained from TALYS optical model calculations with 2316500300008 input parameters identical to those for 232Th(n,gamma) 2316500300009 measurement (Subent 002). 2316500300010 ERR-ANALYS (ERR-1) Systematic errors (about 20%) owing to 2316500300011 introduction of the model-dependent compound nucleus 2316500300012 formation cross section. 2316500300013 STATUS (UNOBT) Fig.10 of J,PR/C,85,034607,2012. 2316500300014 ENDBIB 12 0 2316500300015 COMMON 1 3 2316500300016 ERR-1 2316500300017 PER-CENT 2316500300018 20. 2316500300019 ENDCOMMON 3 0 2316500300020 NODATA 0 0 2316500300021 ENDSUBENT 20 0 2316500399999 SUBENT 23165004 20120817 22332316500400001 BIB 4 12 2316500400002 REACTION (91-PA-231(N,G)91-PA-232,PAR,SIG,,,DERIV) 2316500400003 ANALYSIS (SURGT) Radiative capture c-s deduced via the product 2316500400004 of measured gamma emission probability using the 2316500400005 transfer reaction Th-232(He3,t)Pa-232 . 2316500400006 The compound nucleus formation cross section was 2316500400007 obtained from TALYS optical model calculations with 2316500400008 input parameters identical to those for 232Th(n,gamma) 2316500400009 measurement (Subent 002). 2316500400010 ERR-ANALYS (ERR-1) Systematic errors (about 20%) owing to 2316500400011 introduction of the model-dependent compound nucleus 2316500400012 formation cross section. 2316500400013 STATUS (UNOBT) Fig.11 of J,PR/C,85,034607,2012. 2316500400014 ENDBIB 12 0 2316500400015 COMMON 1 3 2316500400016 ERR-1 2316500400017 PER-CENT 2316500400018 20. 2316500400019 ENDCOMMON 3 0 2316500400020 NODATA 0 0 2316500400021 ENDSUBENT 20 0 2316500499999 ENDENTRY 4 0 2316599999999