The cross section of 3He(3He,2p)4He measured at solar energies

Abstract

We report on the results of the 3 He( 3 He,2p) 4 He experiment at the underground accelerator facility LUNA (Gran Sasso). For the first time the lowest projectile energies utilized for the cross section measurement correspond to energies below the center of the solar Gamow peak (E 0 =22 keV). The data provide no evidence for the existence of a hypothetical resonance in the energy range investigated. Although no extrapolation is needed anymore (except for energies at the low-energy tail of the Gamow peak), the data must be corrected for the effects of electron screening, clearly observed the first time for the 3 He( 3 He,2p) 4 He reaction. The effects are however larger than expected and not understood, leading presently to the largest uncertainty on the quoted S b (E 0 ) value for bare nuclides (=5.40 MeV b).

Recent results and future perspectives with solid targets at LUNA

“…Different accelerators have been used at LUNA in the last 35 years. A 50 kV machine Greife et al (1994), now decommissioned, was mainly used to study hydrogen burning reactions relevant to the Sun, and produced pioneering results (e.g., Junker et al, 1998). In 2001, a 400 kV machine was installed and is still in operation today, with a focus on the reactions part of the Carbon-Nitrogen-Oxygen (CNO) and NeNa cycles in Asymptotic Giant Branch (AGB) stars (Ananna et al, 2021;Masha et al, 2023).…”