Neutron-induced background by an α-beam incident on a deuterium gas target and its implications for the study of the 2H(α,γ)6Li reaction at LUNA

M. Anders; D. Trezzi; A. Bellini; M. Aliotta; D. Bemmerer; C. Broggini; A. Caciolli; H. Costantini; P. Corvisiero; T. Davinson; Z. Elekes; M. Erhard; A. Formicola; Zs. Fülöp; G. Gervino; A. Guglielmetti; C. Gustavino; Gy. Gyürky; M. Junker; A. Lemut; M. Marta; C. Mazzocchi; R. Menegazzo; P. Prati; C. Rossi Alvarez; D. Scott; E. Somorjai; O. Straniero; T. Szücs

doi:10.1140/epja/i2013-13028-5

2022 Impact factor 2.7

Hadrons and Nuclei

Eur. Phys. J. A (2013) 49: 28
https://doi.org/10.1140/epja/i2013-13028-5

Regular Article - Experimental Physics

Neutron-induced background by an α-beam incident on a deuterium gas target and its implications for the study of the ²H(α,γ)⁶Li reaction at LUNA

M. Anders¹, D. Trezzi², A. Bellini³, M. Aliotta⁴, D. Bemmerer¹, C. Broggini⁵, A. Caciolli⁵, H. Costantini³^,a, P. Corvisiero³, T. Davinson⁴, Z. Elekes¹, M. Erhard⁵^,b, A. Formicola⁶, Zs. Fülöp⁷, G. Gervino⁸, A. Guglielmetti⁹^,2, C. Gustavino¹⁰^*, Gy. Gyürky⁷, M. Junker⁶, A. Lemut³^,c, M. Marta¹^,d, C. Mazzocchi²^,e, R. Menegazzo⁵, P. Prati³, C. Rossi Alvarez⁵, D. Scott⁴, E. Somorjai⁷, O. Straniero¹¹^,12, T. Szücs⁷ and LUNA Collaboration

¹ Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany
² INFN, Sezione di Milano, Milano, Italy
³ Dipartimento di Fisica, Università di Genova, and INFN, Sezione di Genova, Genova, Italy
⁴ SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
⁵ INFN, Sezione di Padova, Padova, Italy
⁶ INFN, Laboratori Nazionali del Gran Sasso, Assergi, Italy
⁷ Institute of Nuclear Research (ATOMKI), Debrecen, Hungary
⁸ Dipartimento di Fisica Sperimentale, Università di Torino, and INFN, Torino, Italy
⁹ Università degli Studi di Milano, Milano, Italy
¹⁰ INFN, Sezione di Roma “La Sapienza”, Roma, Italy
¹¹ INFN, Sezione di Napoli, Napoli, Italy
¹² Osservatorio Astronomico di Collurania, Teramo, Italy

^* e-mail: carlo.gustavino@roma1.infn.it

Received: 24 September 2012
Revised: 17 December 2012
Accepted: 28 January 2013
Published online: 26 February 2013

Abstract

The production of the stable isotope ⁶Li in standard Big Bang nucleosynthesis has recently attracted much interest. Recent observations in metal-poor stars suggest that a cosmological ⁶Li plateau may exist. If true, this plateau would come in addition to the well-known Spite plateau of ⁷Li abundances and would point to a predominantly primordial origin of ⁶Li , contrary to the results of standard Big Bang nucleosynthesis calculations. Therefore, the nuclear physics underlying Big Bang ⁶Li production must be revisited. The main production channel for ⁶Li in the Big Bang is the ²H(α,γ)⁶Li reaction. The present work reports on neutron-induced effects in a high-purity germanium detector that were encountered in a new study of this reaction. In the experiment, an α-beam from the underground accelerator LUNA in Gran Sasso, Italy, and a windowless deuterium gas target are used. A low neutron flux is induced by energetic deuterons from elastic scattering and, subsequently, the ²H(d,n)³He reaction. Due to the ultra-low laboratory neutron background at LUNA, the effect of this weak flux of 2-3MeV neutrons on well-shielded high-purity germanium detectors has been studied in detail. Data have been taken at 280 and 400keV α-beam energy and for comparison also using an americium-beryllium neutron source.