International Conference on Nuclear Data for Science and Technology 2007
DOI: 10.1051/ndata:07519

Capture cross section measurements of ^186,187,188Os at n_TOF: the resolved resonance region

K. Fujii¹, M. Mosconi², P.M. Milazzo¹, C. Domingo-Pardo^{2, 3}, F. Käppeler², A. Mengoni^{4, 5}, U. Abbondanno¹, G. Aerts⁶, H. Álvarez⁷, F. Álvarez-Velarde⁸, S. Andriamonje⁶, J. Andrzejewski⁹, P. Assimakopoulos¹⁰, L. Audouin¹¹, G. Badurek¹², P. Baumann¹³, F. Becvár¹⁴, E. Berthoumieux⁶, F. Calviño¹⁵, M. Calviani^{16, 17}, D. Cano-Ott⁸, R. Capote^{4, 18}, C. Carrapiço^{6, 19}, P. Cennini⁵, V. Chepel²⁰, E. Chiaveri⁵, N. Colonna²¹, G. Cortes²², A. Couture²³, J. Cox²³, M. Dahlfors⁵, S. David¹¹, I. Dillmann², W. Dridi⁶, I. Duran⁷, C. Eleftheriadis²⁴, M. Embid-Segura⁸, L. Ferrant¹¹, A. Ferrari⁵, R. Ferreira-Marques²⁰, W. Furman²⁵, I. Goncalves²⁰, E. González-Romero⁸, F. Gramegna¹⁶, C. Guerrero⁸, F. Gunsing⁶, B. Haas²⁶, R. Haight²⁷, M. Heil², A. Herrera-Martinez⁵, M. Igashira²⁸, E. Jericha¹², Y. Kadi⁵, D. Karadimos¹⁰, D. Karamanis¹⁰, M. Kerveno¹³, P. Koehler²⁹, E. Kossionides³⁰, M. Krticka¹⁴, C. Lampoudis^{6, 24}, H. Leeb¹², A. Lindote²⁰, I. Lopes²⁰, M. Lozano¹⁸, S. Lukic¹³, J. Marganiec⁹, S. Marrone²¹, T. Martínez⁸, C. Massimi³¹, P. Mastinu¹⁶, C. Moreau¹, F. Neves²⁰, H. Oberhummer¹², S. O'Brien²³, J. Pancin⁶, C. Papachristodoulou¹⁰, C. Papadopoulos³², C. Paradela⁷, N. Patronis¹⁰, A. Pavlik³³, P. Pavlopoulos³⁴, L. Perrot⁶, M.T. Pigni¹², R. Plag², A. Plompen³⁵, A. Plukis⁶, A. Poch²², J. Praena¹⁶, C. Pretel²², J. Quesada¹⁸, T. Rauscher³⁶, R. Reifarth²⁷, C. Rubbia³⁷, G. Rudolf¹³, P. Rullhusen³⁵, J. Salgado¹⁹, C. Santos¹⁹, L. Sarchiapone⁵, I. Savvidis²⁴, C. Stephan¹¹, G. Tagliente²¹, J.L. Tain³, L. Tassan-Got¹¹, L. Tavora¹⁹, R. Terlizzi²¹, G. Vannini³¹, P. Vaz¹⁹, A. Ventura³⁸, D. Villamarin⁸, M.C. Vincente⁸, V. Vlachoudis⁵, R. Vlastou³², F. Voss², S. Walter², M. Wiescher²³ and K. Wisshak<sup>2

1</sup>  Istituto Nazionale di Fisica Nucleare, Trieste, Italy
²  Forschungszentrum Karlsruhe GmbH (FZK), Institut für Kernphysik, Germany
³  Instituto de Física Corpuscular, CSIC-Universidad de Valencia, Spain
⁴  International Atomic Energy Agency (IAEA), Nuclear Data Section, Vienna, Austria
⁵  CERN, Geneva, Switzerland
⁶  CEA/Saclay-DSM/DAPNIA, Gif-sur-Yvette, France
⁷  Universidade de Santiago de Compostela, Spain
⁸  Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, Madrid, Spain
⁹  University of Lodz, Lodz, Poland
¹⁰  University of Ioannina, Greece
¹¹  Centre National de la Recherche Scientifique/IN2P3-IPN, Orsay, France
¹²  Atominstitut der Österreichischen Universitäten,Technische Universität Wien, Austria
¹³  Centre National de la Recherche Scientifique/IN2P3-IReS, Strasbourg, France
¹⁴  Charles University, Prague, Czech Republic
¹⁵  Universidad Politecnica de Madrid, Spain
¹⁶  Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Italy
¹⁷  Dipartimento di Fisica, Università di Padova, Italy
¹⁸  Universidad de Sevilla, Spain
¹⁹  Instituto Tecnológico e Nuclear (ITN), Lisbon, Portugal
²⁰  LIP-Coimbra & Departamento de Fisica da Universidade de Coimbra, Portugal
²¹  Istituto Nazionale di Fisica Nucleare, Bari, Italy
²²  Universitat Politecnica de Catalunya, Barcelona, Spain
²³  University of Notre Dame, Notre Dame, USA
²⁴  Aristotle University of Thessaloniki, Greece
²⁵  Joint Institute for Nuclear Research, Frank Laboratory of Neutron Physics, Dubna, Russia
²⁶  Centre National de la Recherche Scientifique/IN2P3-CENBG, Bordeaux, France
²⁷  Los Alamos National Laboratory, New Mexico, USA
²⁸  Tokyo Institute of Technology, Tokyo, Japan
²⁹  Oak Ridge National Laboratory, Physics Division, Oak Ridge, USA
³⁰  NCSR, Athens, Greece
³¹  Dipartimento di Fisica, Università di Bologna, and Sezione INFN di Bologna, Italy
³²  National Technical University of Athens, Greece
³³  Institut für Isotopenforschung und Kernphysik, Universität Wien, Austria
³⁴  Pôle Universitaire Léonard de Vinci, Paris-La Défense, France
³⁵  CEC-JRC-IRMM, Geel, Belgium
³⁶  Department of Physics-University of Basel, Switzerland
³⁷  Università degli Studi Pavia, Pavia, Italy
³⁸  ENEA, Bologna, Italy

kfujii@ts.infn.it

Published online: 21 May 2008

Abstract
The neutron capture cross sections of ^186,187,188Os have been measured at the CERN neutron time-of-flight facility, n_TOF, in the neutron energy range from 1 eV up to 1 MeV. In this contribution, we report the results of the analysis of the resolved resonance region (RRR). Resonance parameters have been extracted from a full R-matrix fit of the capture yields with the SAMMY code. A statistical analysis has been performed and the related average resonance parameters are derived. This information is crucial for a complete understanding and modeling in terms of the Hauser-Feshbach statistical model of the capture and inelastic reaction channels, required for the evaluation of the stellar reaction rates of these isotopes. Maxwellian average cross sections for the range of temperatures relevant for s-process nucleosynthesis have been derived from the combined information of the experimental data in the resolved and unresolved resonance regions. A brief account of the implications of this analysis in the estimation of the s-process component of the ¹⁸⁷Os abundance and the related impact on the estimates of the time-duration of the galactic nucleosynthesis through the Re/Os clock is given.

© CEA 2008