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

Author(s)

M. Barbagallo, A. Musumarra, L. Cosentino, E. Maugeri, S. Heinitz, A. Mengoni, R. Dressler, D. Schumann, F. Käppeler, Nicola 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

Abstract

The energy-dependent cross section of the 7Be(n,α)4He 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 7Be 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 7Be, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si−7Be−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.

Organisation(s)

Isotope Physics

External organisation(s)

Università degli Studi di Catania, Istituto Nazionale di Fisica Nucleare (INFN), Roma, Paul Scherrer Institute, Agenzia nazionale per le nuove tecnologie, l’energia e lo sviluppo economico sostenibile, 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, Institute of research into the fundamental laws of the Universe (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 Center, Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering, Japan Atomic Energy Agency, Commiss European Communities, Joint Res Ctr, Inst Reference Mat & Measurements, York University, Tokyo Institute of Technology (TIT), University of Edinburgh, University of Bologna, Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", CNR, Physikalisch-Technische Bundesanstalt, University of Ioannina, Universidad de Granada, University of Hertfordshire, Universität Basel, Australian National University

Journal

Physical Review Letters

Volume

117

No. of pages

7

ISSN

0031-9007

DOI

https://doi.org/10.1103/PhysRevLett.117.152701

Publication date

10-2016

Peer reviewed

Yes

Austrian Fields of Science 2012

103014 Nuclear physics

Keywords

ASJC Scopus subject areas

Physics and Astronomy(all)

Portal url

https://ucris.univie.ac.at/portal/en/publications/be-7-n-he-4-reaction-and-the-cosmological-lithium-problem(9bf2d9d3-8b75-4365-a257-a4df225bbd0a).html