Astrophysically important ²⁶Si states studied with the ²⁸Si(p,t)²⁶Si reaction

D. W. Bardayan, ORNL Physics Division
D. W. Bardayan, The University of North Carolina at Chapel Hill
J. C. Blackmon, ORNL Physics Division
A. E. Champagne, The University of North Carolina at Chapel Hill
A. K. Dummer, The University of North Carolina at Chapel Hill
T. Davinson, The University of Edinburgh
U. Greife, Colorado School of Mines
D. Hill, Tennessee Technological University
C. Iliadis, The University of North Carolina at Chapel Hill
B. A. Johnson, Tennessee Technological University
R. L. Kozub, Tennessee Technological University
C. S. Lee, Chung-Ang University
M. S. Smith, ORNL Physics Division
P. J. Woods, The University of Edinburgh

Abstract

The production of the 26Al radioisotope in astrophysical environments is not understood, in part, because of large uncertainties in key nuclear reaction rates. The 25Al(p, γ)26Si reaction is one of the most important, but its rate is very uncertain as a result of the lack of information on the 26Si level structure above the proton threshold. To reduce these uncertainties, we have measured differential cross sections for the 28Si(p,t)26Si reaction and determined excitation energies for states in 26Si. A total of 21 states in 26Si were observed, including ten above the proton threshold. One new state at 7019 kev was observed, the excitation energies of several states were corrected, and the uncertainties in the excitation energies of other states were significantly reduced. Spins and parities of several states above the proton threshold were determined for the first time through a distorted-wave Born approximation analysis of the angular distributions. These results substantially clarify the level structure of 26Si.