Spectroscopic factor of the 1+, 25Al(p,g)26Si resonance at Ex=5.68 MeV

Abstract

Nuclear shell model predictions for the proton spectroscopic factor of the 1+, Ex = 5.68 MeV level in 26Si are about fifty times smaller than the value suggested by the measured (a,3He) cross section for the Ex = 5.69 MeV mirror level in 26Mg, assuming purely single-particle transfer. Given that the 5.69 MeV level has been very weakly, if it all, populated in previous studies of the simpler 25Mg(d,p) reaction, it is unclear if the (a,3He) result is a true single-particle spectroscopic factor. If we assume the (a,3He) result, the thermonuclear rate of the 25Al(p,g)26Si reaction would increase by factors of 6 - 50 over stellar temperatures of T = 0.05 - 0.2 GK. We examine the implications of this enhanced rate for model predictions of nucleosynthesis in classical nova explosions.