Destruction of 7Li and 7Be in astrophysical environments Original Research Article

The destruction of 7Li and 7Be in astrophysical environments is essential for understanding several stellar and cosmological processes and is not well understood, though earlier 7Li + 3He experiments have been performed [1]. The primordial abundance of 7Li after Big Bang Nucleosynthesis (BBN) plays a major role in our understanding of the early universe [2]. The value of the baryon to photon ratio (η) deduced from BBN combined with measurements of the cosmic microwave background provide some of the strongest and earliest evidence for the existance of non-baryonic dark matter [2]. The destruction of 7Be during the hot-pp cycle may alter our conclusions on the production of carbon in this process, which is thought to compete with the triple-α process for the production of 12C, as the reaction 7Be(3He, 2α)2p competes with 7Be(4He, γ)11C and may reduce carbon production [3]. These stellar and cosmological environments involve high temperatures, and thus, effective burning energies (Gamow windows) that are quite high. Experiments using 7Be targets inevitably involve interactions with 7Li as background due to the 7Li daughters from the beta decay of 7Be. The experiments were performed at the Weizmann Institute VDG Laboratory using 3He beams from 390 keV to 1130 keV on 7LiF foil targets and 7Be implanted targets. Results from measurements using 10 μg 7LiF foil targets will be discussed.