Be 7 (n,α) He 4 Reaction and the Cosmological Lithium Problem

M. Barbagallo, A. Musumarra, L. Cosentino, E. Maugeri, S. Heinitz, A. Mengoni, R. Dressler, D. Schumann, F. Käppeler, N. Colonna, P. Finocchiaro, M. Ayranov, L. Damone, N. Kivel, O. Aberle, S. Altstadt, J. Andrzejewski, L. Audouin, M. Bacak, J. Balibrea-Correa, S. Barros, V. Bécares, F. Bečvář, C. Beinrucker, E. Berthoumieux, J. Billowes, D. Bosnar, M. Brugger, M. Caamaño, M. Calviani, F. Calviño, D. Cano-Ott, R. Cardella, A. Casanovas, D. M. Castelluccio, F. Cerutti, Y. H. Chen, E. Chiaveri, G. Cortés, M. A. Cortés-Giraldo, S. Cristallo, M. Diakaki, C. Domingo-Pardo, E. Dupont, I. Duran, B. Fernandez-Dominguez, A. Ferrari, P. Ferreira, W. Furman, S. Ganesan, A. García-Rios, A. Gawlik, T. Glodariu, K. Göbel, I. F. Gonçalves, E. González-Romero, E. Griesmayer, C. Guerrero, F. Gunsing, H. Harada, T. Heftrich, J. Heyse, D. G. Jenkins, E. Jericha, T. Katabuchi, P. Kavrigin, A. Kimura, M. Kokkoris, M. Krtička, E. Leal-Cidoncha, J. Lerendegui, C. Lederer, H. Leeb, S. Lo Meo, S. J. Lonsdale, R. Losito, D. Macina, J. Marganiec, T. Martínez, C. Massimi, P. Mastinu, M. Mastromarco, A. Mazzone, E. Mendoza, P. M. Milazzo, F. Mingrone, M. Mirea, S. Montesano, R. Nolte, A. Oprea, A. Pappalardo, N. Patronis, Andreas Pavlik, J. Perkowski, M. Piscopo, A. Plompen, I. Porras, J. Praena, J. Quesada, K. Rajeev, T. Rauscher, R. Reifarth, A. Riego-Perez, P. Rout, C. Rubbia, J. Ryan, M. Sabate-Gilarte, A. Saxena, P. Schillebeeckx, S. Schmidt, P. Sedyshev, A. G. Smith, A. Stamatopoulos, G. Tagliente, J. L. Tain, A. Tarifeño-Saldivia, L. Tassan-Got, A. Tsinganis, S. Valenta, G. Vannini, V. Variale, P. Vaz, A. Ventura, V. Vlachoudis, R. Vlastou, J. Vollaire, Anton Wallner, S. Warren, M. Weigand, C. Weiß, C. Wolf, P. J. Woods, T. Wright, P. Žugec

The energy-dependent cross section of the Be7(n,α)He4 reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of Be7 and by the low reaction cross section have been overcome at n-TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n-TOF facility at CERN, the availability of a sufficient amount of chemically pure Be7, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si-Be7-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n-TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.

Externe Organisation(en)
Università degli Studi di Catania, Istituto Nazionale di Fisica Nucleare, Roma, Paul Scherrer Institute, ENEA Centro Ricerche Bologna, Karlsruher Institut für Technologie, European Commission, European Organization for Nuclear Research (CERN), Johann Wolfgang Goethe-Universität Frankfurt am Main, University of Lodz, Université Paris XI - Paris-Sud, Technische Universität Wien, Centro de Investigaciones Energeticas Medioambientales y Tecnológica, Universidade de Lisboa, Charles University Prague, IRFU, Manchester Metropolitan University, University of Zagreb, Universidade de Santiago de Compostela (USC), Universitat Politècnica de Catalunya, Universidad de Sevilla, Osservatorio Astronomico di Collurania Vincenzo Cerulli, National Technical University of Athens (NTUA), Universitat de València, Joint Institute for Nuclear Research, Bhabha Atomic Research Centre, Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN HH), Japan Atomic Energy Agency, Institute for Reference Materials and Measurements, York University, Tokyo Institute of Technology (TIT), University of Edinburgh, Università degli Studi di Bologna, Consiglio Nazionale delle Ricerche (CNR), Rom, Physikalisch-Technische Bundesanstalt (PTB), University of Ioannina, Universidad de Granada, University of Hertfordshire, Universität Basel, Australian National University
Physical Review Letters
ÖFOS 2012
103014 Kernphysik
ASJC Scopus Sachgebiete
Physics and Astronomy(all)
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