Production of proton-rich nuclei beyond iron in stars proceeds via the p process, i.e., a sequence of photodisintegration reactions, (gamma,n), (gamma,p), and (gamma,alpha) on heavy nuclei 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, Cd-106, Sn-118, and Te-120,Te-124,Te-126,Te-128,Te-130 were studied at energies both below and above the Coulomb barrier. A new parametrization of the a optical potential was derived of the elastic scattering cross section data. The derived potential was applied for calculating the alpha-induced reaction cross sections on these nuclei using the HF approach. The results were compared to the corresponding experimental values obtained from previous activation measurements on Cd, Sn, and Te isotopes.

The cross section of the reaction $^{112}\mathrm{Sn}$($\ensuremath{\alpha},\ensuremath{\gamma})^{116}\mathrm{Te}$ has been measured in the energy range of astrophysical interest for the $p$-process. Highly enriched self-supporting $^{112}\mathrm{Sn}$ foils were bombarded with \ensuremath{\alpha} beams in the effective center of mass energy range from 7.59 to 11.42 MeV at the Notre Dame FN Tandem Van de Graaff accelerator. The characteristic activity of $^{116}\mathrm{Te}$ was counted with a pair of large volume Ge clover detectors in close geometry to maximize the detection efficiency. The cross section of the concurrent ($\ensuremath{\alpha},p$) reaction has also been measured. The results are compared with statistical model predictions for different global \ensuremath{\alpha}-nucleus potentials.

The cross section of the reaction Sn-112(alpha,gamma)Te-116 has been measured in the energy range of astrophysical interest for the p-process. Highly enriched self-supporting Sn-112 foils were bombarded with alpha beams in the effective center of mass energy range from 7.59 to 11.42 MeV at the Notre Dame FN Tandem Van de Graaff accelerator. The characteristic activity of Te-116 was counted with a pair of large volume Ge clover detectors in close geometry to maximize the detection efficiency. The cross section of the concurrent (alpha,p) reaction has also been measured. The results are compared with statistical model predictions for different global alpha-nucleus potentials.

The simulation of p-process nucleosynthesis requires thousands of reaction rates. These rates are typically calculated with the statistical Hauser Feshbach Model (HF-Model) which depends critically on the reliability of the optical nucleus potential. In particular, the predicted (alpha,gamma) cross sections at low energies (below 20 MeV) are sensitive to the choice of the alpha potential. Dscrepancies have been observed between the experimental cross sections and the theoretical values (NON-SMOKER). Currently, only a few alpha-induced reaction rates have been measured. To explore the trend Cd-106(alpha,gamma)Sn-110 and Sn-112(alpha,gamma)Te-116 cross sections were measured at the Notre Dame FN Tandem accelerator. First results are presented and discussed.

in the present work both the (alpha,gamma) and (p,gamma) cross sections on the p-nucleus Cd-106 have been measured in the energy range relevant to the astrophysical p-process. The results are compared with the predictions of the statistical model calculations implemented with the NON-SMOKER code using different input parameters. The proton capture cross section has also been measured for Cd-108.The alpha + Cd-106 optical potential, an important input parameter for the Cd-106(alpha,gamma) reaction rate determination, can be determined directly by measuring the deviation from the Rutherford scattering in the Cd-106(alpha,alpha)Cd-106 elastic scattering experiment. This experiment has also been performed in a wide angular range and the results are compared with different global optical potentials.

The 106Cd(alpha,gamma)110Sn reaction cross section has been measured in the energy range of the Gamow window for the astrophysical p-process scenario. The cross sections for 106Cd(alpha,n)109Sn and for 106Cd(alpha,p)109In below the (alpha,n) threshold have also been determined. The results are compared with predictions of the statistical model code NON-SMOKER using different input parameters. The comparison shows that a discrepancy for 106Cd(alpha,gamma)110Sn when using the standard optical potentials can be removed with a different alpha+106Cd potential. Some astrophysical implications are discussed.

The 112Sn(α,γ)116Te reaction cross-section has been measured to test the applicability of statistical models, especially NON-SMOKER in the energy range of importance for the astrophysical p-process nucleosynthesis. The measurements were carried out at the Notre Dame FN Tandem Van de Graaff accelerator by means of the activation method. Enriched self-supporting foils were irradiated with alpha beams over the alpha bombarding energy range of 8MeV to 12MeV in 0.5MeV steps. The induced activity was measured with a pair of large volume Ge Clover detectors in close geometry to maximize the detection efficiency. The preliminary results are compared with recent statistical model predictions using the code NON-SMOKER.