Astrophysically important Si26 states studied with the Si28(p,t)Si26 reaction. II. Spin of the 5.914-MeV Si26 level and galactic Al26 production

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


The Si28(p,t)Si26 reaction has been studied to resolve a controversy surrounding the properties of the Si26 level at 5.914 MeV and its contribution to the Al25(p,γ)Si26 reaction rate in novae, which affects interpretations of galactic Al26 observations. Recent studies have come to contradictory conclusions regarding the spin of this level (0+ or 3+), with a 3+ assignment implying a large contribution by this level to the Al25(p,γ)Si26 reaction rate. We have extended our previous study [Bardayan, Phys. Rev. C 65, 032801(R) (2002)] to smaller angles and find the angular distribution of tritons populating the 5.914-MeV level in the Si28(p,t)Si26 reaction to be consistent with either a 2+ or 3+ assignment. We have calculated reaction rates under these assumptions and used them in a nova nucleosynthesis model to examine the effects of the remaining uncertainties in the Al25(p,γ)Si26 rate on Al26 production in novae. © 2006 The American Physical Society.