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

The reaction 141Pr(α,n)144pm 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 microbam 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 145pm and 148Gd were explored. In summary, the data and further results underline the problems in global predictions of α + nucleus optical potentials at astrophysically relevant energies. [ABSTRACT FROM AUTHOR]