p-process nucleosynthesis: Activation experiments

For the astrophysical p   process a complex reaction network has to be solved. In the order of 10,000 theoretically predicted reaction rates are needed for simulations of this network. For reactions involving αα particles or protons, the predictions in the framework of the Hauser–Feshbach (HF) model were found to deviate from experimental results partially by a factor of 55 or even more. To optimize the predictive power of the applied HF codes, the nuclear physics input has to be improved. For this purpose, the reactions 166Er(α,n) and 169Tm(p,n) as well as the reaction 170Yb(γ,n) have been measured with the activation method at low energies. The data can provide a further test of HF predictions but can also be used to optimize input parameters of the afore mentioned codes. Preliminary results of the experiments are presented and compared to theoretical predictions using the standard settings of the HF codes NON-SMOKER and TALYS.