Study of Si-26 states important for Al-26 nucleosynthesis in novae

Abstract

The production of the radioisotope 26 Al in astrophysical environments is not understood, in part, because of large uncertainties in key reaction rates such as 25 Al(p, γ 26 Si. To reduce the uncertainty in this rate, we have studied the level structure of 26 Si via a measurement of the angular and energy distribution of tritons from the 28 (p, t 26 i reaction. A total of 21 states in 26 Si were observed, including a new state at 7019 keV. The excitation energies of several states were corrected, and the spin assignments for several states above the proton emission threshold were determined for the first time through a DWBA analysis of the angular distributions. Our results substantially clarify the level structure of 26 Si and improve our understanding of the 25 Al(p, γ) 26 Si reaction rate.