Abstract
Model predictions of the amount of the radioisotope Al produced in hydrogen-burning environments require reliable estimates of the thermonuclear rates for the Al(,γ) Si and Al(,γ)Si reactions. These rates depend upon the spectroscopic properties of states in Si within about 1 MeV of the Al + threshold ( = 7463 keV). We have studied the Si(He,α)Si reaction at 25 MeV using a high-resolution quadrupole-dipole-dipole-dipole magnetic spectrograph. For the first time with a transfer reaction, we have constrained values for states in Si over = 7.0–8.1 MeV through angular distribution measurements. Aside from a few important cases, we generally confirm the energies and spin-parity assignments reported in a recent γ-ray spectroscopy study. The magnitudes of neutron spectroscopic factors determined from shell-model calculations are in reasonable agreement with our experimental values extracted using this reaction.
- Received 22 August 2011
DOI:https://doi.org/10.1103/PhysRevC.84.065808
©2011 American Physical Society