Study of the contribution of the 7Be(d, p) reaction to the 7Li problem in the Big-Bang Nucleosynthesis

Abstract

Our research goal is to measure the cross section of the 7Be(d, p) reaction to find a solution for the cosmological the 7Li problem, which is an overestimation of the primordial 7Li abundance in the standard Big-Bang nucleosynthesis (BBN) model. We developed a method to produce an unstable 7Be target to measure the reaction in normal kinematics in a high-resolution measurement. We performed an experiment to produce the 7Be target and also to measure the cross section of the 7Be(d, p)8Be reaction with the produced 7Be target at the tandem facility, Kobe University. A 2.36 MeV proton beam irradiated a Li target to transmute 7Li particles to 7Be particles via the 7Li(p, n)7Be reaction. We produced 2.6×1013 7Be particles in the target after two days’ proton irradiation. After the target production, the beam ion was changed to deuterons with energies of 0.6, 1.0, and 1.6 MeV to measure the 7Be(d, p) reaction. The outgoing protons were measured by two ΔE-E silicon telescopes placed at 30° and 45°. We report the preliminary results of this experiment, including the 7Be(d, p) cross section.