title: ^{7}Be(n,α)^{4}He Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN.
abstract: The energy-dependent cross section of the ^{7}Be(n,α)^{4}He 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 ^{7}Be 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 ^{7}Be, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si-^{7}Be-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.
authors: INFN, Sezione di Bari, Italy.
authors: M
authors: M
authors: Barbagallo
authors: Dipartimento di Fisica e Astronomia DFA, Università di Catania, Italy.|INFN-Laboratori Nazionali del Sud, Catania, Italy.
authors: A
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authors: Musumarra
authors: INFN-Laboratori Nazionali del Sud, Catania, Italy.
authors: L
authors: L
authors: Cosentino
authors: Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
authors: E
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authors: Maugeri
authors: Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
authors: S
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authors: Heinitz
authors: ENEA, Bologna, Italy.
authors: A
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authors: Mengoni
authors: Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
authors: R
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authors: Dressler
authors: Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
authors: D
authors: D
authors: Schumann
authors: Karlsruhe Institute of Technology (KIT), Institut für Kernphysik, Karlsruhe, Germany.
authors: F
authors: F
authors: Käppeler
authors: INFN, Sezione di Bari, Italy.
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authors: Colonna
authors: INFN-Laboratori Nazionali del Sud, Catania, Italy.
authors: P
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authors: Finocchiaro
authors: European Commission, DG-Energy, Luxembourg.
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authors: INFN, Sezione di Bari, Italy.
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authors: Damone
authors: Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
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authors: Kivel
authors: CERN, Geneva, Switzerland.
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authors: Johann-Wolfgang-Goethe Universität, Frankfurt, Germany.
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authors: S
authors: Altstadt
authors: Uniwersytet Łódzki, Lodz, Poland.
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authors: Andrzejewski
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authors: Centro de Investigaciones Energeticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain.
authors: J
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authors: C2TN-Instituto Superior Tecníco, Universidade de Lisboa, Portugal.
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authors: Centro de Investigaciones Energeticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain.
authors: V
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authors: Charles University, Prague, Czech Republic.
authors: F
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authors: Bečvář
authors: Johann-Wolfgang-Goethe Universität, Frankfurt, Germany.
authors: C
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authors: Beinrucker
authors: CEA/Saclay-IRFU, Gif-sur-Yvette, France.
authors: E
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authors: Berthoumieux
authors: University of Manchester, Oxford Road, Manchester, United Kingdom.
authors: J
authors: J
authors: Billowes
authors: Department of Physics, Faculty of Science, University of Zagreb, Croatia.
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authors: Bosnar
authors: CERN, Geneva, Switzerland.
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authors: Universidade de Santiago de Compostela, Spain.
authors: M
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authors: CERN, Geneva, Switzerland.
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authors: Calviani
authors: Universitat Politecnica de Catalunya, Barcelona, Spain.
authors: F
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authors: Calviño
authors: Centro de Investigaciones Energeticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain.
authors: D
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authors: Cano-Ott
authors: INFN-Laboratori Nazionali del Sud, Catania, Italy.|CERN, Geneva, Switzerland.
authors: R
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authors: Universitat Politecnica de Catalunya, Barcelona, Spain.
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authors: Casanovas
authors: ENEA, Bologna, Italy.
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authors: Castelluccio
authors: CERN, Geneva, Switzerland.
authors: F
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authors: Cerutti
authors: Centre National de la Recherche Scientifique/IN2P3-IPN, Orsay, France.
authors: Y H
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authors: CERN, Geneva, Switzerland.
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authors: Chiaveri
authors: Universitat Politecnica de Catalunya, Barcelona, Spain.
authors: G
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authors: Cortés
authors: Universidad de Sevilla, Spain.
authors: M A
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authors: Cortés-Giraldo
authors: INAF-Osservatorio Astronomico di Collurania, Teramo, Italy.
authors: S
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authors: Cristallo
authors: National Technical University of Athens (NTUA), Greece.
authors: M
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authors: Diakaki
authors: Instituto de Física Corpuscular, CSIC-Universidad de Valencia, Spain.
authors: C
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authors: Domingo-Pardo
authors: CEA/Saclay-IRFU, Gif-sur-Yvette, France.
authors: E
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authors: Dupont
authors: Universidade de Santiago de Compostela, Spain.
authors: I
authors: I
authors: Duran
authors: Universidade de Santiago de Compostela, Spain.
authors: B
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authors: Fernandez-Dominguez
authors: CERN, Geneva, Switzerland.
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authors: Ferrari
authors: C2TN-Instituto Superior Tecníco, Universidade de Lisboa, Portugal.
authors: P
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authors: Joint Institute of Nuclear Research, Dubna, Russia.
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authors: Bhabha Atomic Research Centre (BARC), Mumbai, India.
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authors: Ganesan
authors: Centro de Investigaciones Energeticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain.
authors: A
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authors: García-Rios
authors: Uniwersytet Łódzki, Lodz, Poland.
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authors: Horia Hulubei National Institute of Physics and Nuclear Engineering-IFIN HH, Bucharest-Magurele, Romania.
authors: T
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authors: Glodariu
authors: Johann-Wolfgang-Goethe Universität, Frankfurt, Germany.
authors: K
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authors: Göbel
authors: C2TN-Instituto Superior Tecníco, Universidade de Lisboa, Portugal.
authors: I F
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authors: Centro de Investigaciones Energeticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain.
authors: E
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authors: Atominstitut der Österreichischen Universitäten, Technische Universität Wien, Austria.
authors: E
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authors: Universidad de Sevilla, Spain.
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authors: Guerrero
authors: CEA/Saclay-IRFU, Gif-sur-Yvette, France.
authors: F
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authors: Japan Atomic Energy Agency (JAEA), Tokai-mura, Japan.
authors: H
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authors: Harada
authors: Johann-Wolfgang-Goethe Universität, Frankfurt, Germany.
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authors: European Commission JRC, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium.
authors: J
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authors: University of York, Heslington, York, United Kingdom.
authors: D G
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authors: Atominstitut der Österreichischen Universitäten, Technische Universität Wien, Austria.
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authors: Tokyo Institute of Technology, Japan.
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authors: Atominstitut der Österreichischen Universitäten, Technische Universität Wien, Austria.
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authors: Charles University, Prague, Czech Republic.
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authors: Universidade de Santiago de Compostela, Spain.
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authors: Leal-Cidoncha
authors: Universidad de Sevilla, Spain.
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authors: School of Physics and Astronomy, University of Edinburgh, United Kingdom.
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authors: ENEA, Bologna, Italy.|INFN, Sezione di Bologna, Italy.
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authors: School of Physics and Astronomy, University of Edinburgh, United Kingdom.
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authors: CERN, Geneva, Switzerland.
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authors: Centro de Investigaciones Energeticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain.
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authors: INFN, Sezione di Bologna, Italy.|Dipartimento di Fisica e Astronomia, Università di Bologna.
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authors: INFN, Sezione di Bari, Italy.
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authors: INFN, Sezione di Bari, Italy.|CNR-IC, Bari, Italy.
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authors: Centro de Investigaciones Energeticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain.
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authors: Horia Hulubei National Institute of Physics and Nuclear Engineering-IFIN HH, Bucharest-Magurele, Romania.
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authors: European Commission JRC, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium.
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authors: Centre for Astrophysics Research, School of Physics, Astronomy and Mathematics, University of Hertfordshire, Hatfield, United Kingdom.|Department of Physics, University of Basel, Basel, Switzerland.
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authors: CERN, Geneva, Switzerland.
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authors: European Commission JRC, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium.
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authors: Johann-Wolfgang-Goethe Universität, Frankfurt, Germany.
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authors: INFN, Sezione di Bari, Italy.
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authors: Instituto de Física Corpuscular, CSIC-Universidad de Valencia, Spain.
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authors: Tarifeño-Saldivia
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authors: CERN, Geneva, Switzerland.
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authors: INFN, Sezione di Bologna, Italy.|Dipartimento di Fisica e Astronomia, Università di Bologna.
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authors: CERN, Geneva, Switzerland.
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authors: University of Vienna, Faculty of Physics, Austria.|Research School of Physics and Engineering, Australian National University, ACT 0200, Australia.
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authors: University of Manchester, Oxford Road, Manchester, United Kingdom.
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authors: Johann-Wolfgang-Goethe Universität, Frankfurt, Germany.
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authors: Johann-Wolfgang-Goethe Universität, Frankfurt, Germany.
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authors: School of Physics and Astronomy, University of Edinburgh, United Kingdom.
authors: P J
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authors: University of Manchester, Oxford Road, Manchester, United Kingdom.
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authors: Department of Physics, Faculty of Science, University of Zagreb, Croatia.
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