³He(α,γ)⁷Be cross section measurement around ⁷Be known energy levels

¹ Institute for Nuclear Research (ATOMKI), Debrecen, Hungary
² University of Debrecen, Doctoral School of Physics, Debrecen, Hungary

E-mail: toth.akos@atomki.hu

Published online: 24 February 2022

Abstract

The ³He(α,γ)⁷Be reaction plays an important role in two astrophysical scenarios. It is a key reaction in lithium production during the Big Bang Nucleosynthesis and one of the central reaction in the p-p chain in stars. In the case of the former event, the Gamow energy of the reaction is around 0.2 MeV, while in the case of the p-p chain in the Sun, an order of magnitude less, around 0.023 MeV. Experimental investigation at such low energies is very difficult, if possible at all, thus low energy extrapolation inevitable to predict the reaction rate at these energies. The extrapolation and its uncertainty are influenced by the precision and covered energy range of the data used. There are many precision datasets between E_c.m. = 0.3–3.1 MeV, but only one below and one above. At higher energies known levels of ⁷Be exist, which motivates the study of that energy range. Therefore, we performed investigations in the energy range of E_c.m. = 4.3–8.3 MeV, where the radiative cross section has not been studied so far. For the cross section determination, the activation technique was used utilising a thin-windowed gas cell and the MGC-20 cyclotron of ATOMKI.