Systematic study of alpha-optical potential near the Z=50 region for p-process*

Production of proton-rich elements beyond iron in stars proceeds via p-process, i.e., a sequence of photo-disintegration reactions, ($\gamma$,n), ($\gamma$,p), and ($\gamma$,$\alpha$) on heavy elements at temperatures of 2-3 x 10$^9$ K. The involved reaction rates are typically calculated with the statistical Hauser-Feshbach (HF) model. However, the HF model performs poorly in calculating the critical ($\gamma$,$\alpha$) rates due to the uncertainty of the alpha optical potentials applied. To test the reliability of the HF calculations and provide a systematic understanding of the alpha optical potential at energies of astrophysical interest, a series of precision alpha scattering measurements were carried out at the Notre Dame FN tandem accelerator. Specifically, $^{106}$Cd, $^{118}$Sn, and $^{120,124,126,128,130}$Te were studied at energies both below and above the Coulomb barrier. The derived potential was applied for calculating the $\alpha$-induced reaction rates on these nuclei using the CIGAR code. The results were compared to the corresponding experimental rates obtained via activation experiments at Notre Dame and other places.