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
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
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.
© SIF, Springer-Verlag Berlin Heidelberg, 2013