Статья

First Direct Measurement of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mrow><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">H</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>α</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi><mml:mo stretchy="false">)</mml:mo><mml:mmultiscripts><mml:mrow><mml:mi>Li</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:mrow></mml:math>Cross Section at Big Bang Energies and the Primordial Lithium Problem

M. AndersHelmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany and Technische Universität Dresden, Mommsenstrasse 9, 01069 Dresden, GermanyD. TrezziUniversità degli Studi di Milano and INFN, Sezione di Milano, Via G. Celoria 16, 20133 Milano, ItalyR. MenegazzoINFN, Sezione di Padova, Via F. Marzolo 8, 35131 Padova, ItalyM. AliottaSUPA, School of Physics and Astronomy, University of Edinburgh, EH9 3JZ Edinburgh, United KingdomAndrea BelliniUniversità degli Studi di Genova and INFN, Sezione di Genova, Via Dodecaneso 33, 16146 Genova, ItalyD. BemmererHelmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, GermanyC. BrogginiINFN, Sezione di Padova, Via F. Marzolo 8, 35131 Padova, ItalyA. CaciolliINFN, Sezione di Padova, Via F. Marzolo 8, 35131 Padova, ItalyP. CorvisieroUniversità degli Studi di Genova and INFN, Sezione di Genova, Via Dodecaneso 33, 16146 Genova, ItalyH. CostantiniUniversità degli Studi di Genova and INFN, Sezione di Genova, Via Dodecaneso 33, 16146 Genova, ItalyT. DavinsonSUPA, School of Physics and Astronomy, University of Edinburgh, EH9 3JZ Edinburgh, United KingdomZ. ElekesHelmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, GermanyM. ErhardINFN, Sezione di Padova, Via F. Marzolo 8, 35131 Padova, ItalyA. FormicolaLaboratori Nazionali del Gran Sasso (LNGS), Via G. Acitelli 22, 67100 Assergi, ItalyZs. FülöpInstitute of Nuclear Research (MTA ATOMKI), PO Box 51, HU-4001 Debrecen, HungaryG. GervinoUniversità degli Studi di Torino and INFN, Sezione di Torino, Via P. Giuria 1, 10125 Torino, ItalyA. GuglielmettiUniversità degli Studi di Milano and INFN, Sezione di Milano, Via G. Celoria 16, 20133 Milano, ItalyC. GustavinoINFN, Sezione di Roma "La Sapienza", Piazzale A. Moro 2, 00185 Roma, ItalyGy. GyürkyInstitute of Nuclear Research (MTA ATOMKI), PO Box 51, HU-4001 Debrecen, HungaryM. JunkerLaboratori Nazionali del Gran Sasso (LNGS), Via G. Acitelli 22, 67100 Assergi, ItalyA. LemutUniversità degli Studi di Genova and INFN, Sezione di Genova, Via Dodecaneso 33, 16146 Genova, ItalyM. MartaHelmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, GermanyC. MazzocchiUniversità degli Studi di Milano and INFN, Sezione di Milano, Via G. Celoria 16, 20133 Milano, ItalyP. PratiUniversità degli Studi di Genova and INFN, Sezione di Genova, Via Dodecaneso 33, 16146 Genova, ItalyC. Rossi AlvarezINFN, Sezione di Padova, Via F. Marzolo 8, 35131 Padova, ItalyD. A. ScottSUPA, School of Physics and Astronomy, University of Edinburgh, EH9 3JZ Edinburgh, United KingdomE. SomorjaiInstitute of Nuclear Research (MTA ATOMKI), PO Box 51, HU-4001 Debrecen, HungaryO. StranieroOsservatorio Astronomico di Collurania, Via M. Maggini, 64100 Teramo, Italy and INFN, Sezione di Napoli, Via Cintia, 80126 Napoli, ItalyT. SzücsInstitute of Nuclear Research (MTA ATOMKI), PO Box 51, HU-4001 Debrecen, Hungary

2014lv

ABI

Аннотация

Recent observations of $^{6}\mathrm{Li}$ in metal poor stars suggest a large production of this isotope during big bang nucleosynthesis (BBN). In standard BBN calculations, the $^{2}\mathrm{H}(\ensuremath{\alpha},\ensuremath{\gamma})^{6}\mathrm{Li}$ reaction dominates $^{6}\mathrm{Li}$ production. This reaction has never been measured inside the BBN energy region because its cross section drops exponentially at low energy and because the electric dipole transition is strongly suppressed for the isoscalar particles $^{2}\mathrm{H}$ and $\ensuremath{\alpha}$ at energies below the Coulomb barrier. Indirect measurements using the Coulomb dissociation of $^{6}\mathrm{Li}$ only give upper limits owing to the dominance of nuclear breakup processes. Here, we report on the results of the first measurement of the $^{2}\mathrm{H}(\ensuremath{\alpha},\ensuremath{\gamma})^{6}\mathrm{Li}$ cross section at big bang energies. The experiment was performed deep underground at the LUNA 400 kV accelerator in Gran Sasso, Italy. The primordial $^{6}\mathrm{Li}/^{7}\mathrm{Li}$ isotopic abundance ratio has been determined to be $(1.5\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, from our experimental data and standard BBN theory. The much higher $^{6}\mathrm{Li}/^{7}\mathrm{Li}$ values reported for halo stars will likely require a nonstandard physics explanation, as discussed in the literature.

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Идентификаторы

DOI: 10.1103/physrevlett.113.042501

Цитирования и источники

Цитирований: 9Использованных источников: 0

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