Determination of 141 Pr(α,n) 144 Pm cross sections at energies of relevance for the astrophysical p process using the γγ coincidence method

The reaction 141 Pr(α,n) 144 Pm was investigated between Eα = 11 MeV and 15 MeV with the activation method using the γγ coincidence method with a segmented clover-type high-purity Germanium (HPGe) detector. Measurements with four other HPGe detectors were additionally made. The comparison proves that the γγ coincidence method is an excellent tool to investigate cross sections down to the microbarn range. The (α,n) reaction at low energy is especially suited to test α + nucleus optical-model potentials for application in the astrophysical p process. The experimentally determined cross sections were compared to Hauser-Feshbach statistical model calculations using different optical potentials and generally an unsatisfactory reproduction of the data was found. A local potential was constructed to improve the description of the data. The consequences of applying the same potential to calculate astrophysical( γ,α ) rates for 145 Pm and 148 Gd were explored. In summary, the data and further results underline the problems in global predictions of α + nucleus optical potentials at astrophysicallyrelevant energies.