The ²⁵Al(p,γ)²⁶Si reaction rate in novae

D. W. Bardayan, ORNL Physics Division
J. C. Blackmon, ORNL Physics Division
W. R. Hix, ORNL Physics Division
J. F. Liang, ORNL Physics Division
M. S. Smith, ORNL Physics Division
J. A. Howard, Tennessee Technological University
R. L. Kozub, Tennessee Technological University
C. R. Brune, Ohio University
K. Y. Chae, The University of Tennessee, Knoxville
E. J. Lingerfelt, The University of Tennessee, Knoxville
J. P. Scott, The University of Tennessee, Knoxville
M. S. Johnson, Oak Ridge Associated Universities
K. L. Jones, Rutgers University–New Brunswick
S. D. Pain, Rutgers University–New Brunswick
J. S. Thomas, Rutgers University–New Brunswick
R. J. Livesay, Colorado School of Mines
D. W. Visser, The University of North Carolina at Chapel Hill

Abstract

The production of 26Al in novae is uncertain, in part, because of the uncertain rate of the 25Al(p,γ)26Si reaction at novae temperatures. This reaction is thought to be dominated by a long-sought 3+ level in 26Si, and the calculated reaction rate varies by orders of magnitude depending on the energy of this resonance. We present evidence concerning the spin of a level at 5.914 MeV in 26Si from the 28Si(p,t)26Si reaction studied at the Holifield Radioactive Beam Facility at ORNL. We find that the angular distribution for this level implies either a 2+ or 3+ assignment, with only a 3+ being consistent with the mirror nucleus, 26Mg. Additionally, we have used the updated 25Al(p,γ)26Si reaction rate in a nova nucleosynthesis calculation and have addressed the effects of the remaining uncertainties in the rate on 26Al production. © Copyright owned by the author(s).