Astrophysical S factor for the He-4(He-3,gamma)Be-7 reaction at medium energies

3 pags., 1 tab. -- Nuclear Physics in Astrophysics V 3–8 April 2011, Eilat, IsraelThe astrophysical S factor for the He-4(He-3,gamma)Be-7 direct capture reaction plays a major role in the context of solar neutrino flux and primordial Li-7 abundances that demand accurate information on the reaction. We report here our recent cross section measurements using the activation method in the region of E-CM=900-2800 keV, that aim to shed light on the discrepancies in the existing data and lead to a more accurate extrapolation of the S factor

Recoil-beta tagging study of the N = Z nucleus As-66

An in-beam study has been performed to further investigate the known isomeric decays and to identify T = 1 excited states in the medium-heavy N = Z = 33 nucleus As-66. The fusion-evaporation reaction Ca-40(Si-28,pn)As-66 was employed at beam energies of 75 and 83 MeV. The half-lives and ordering of two known isomeric states in As-66 have been determined with improved accuracy. In addition, several prompt gamma-ray transitions from excited states, both bypassing and decaying to the isomeric states in As-66, have been observed. Most importantly, candidates for the 4(+) -> 2(+) and 6(+) -> 4(+) transitions in the T = 1 band have been identified. The results are compared with shell-model calculations using the modern JUN45 interaction in the pf(5/2)g(9/2) model space