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

TL;DR

This study measured the 141Pr(alpha,n)144Pm reaction cross sections at energies relevant for the astrophysical p-process using gamma-gamma coincidence detection, highlighting challenges in modeling alpha-nucleus interactions.

Contribution

It introduces the gamma-gamma coincidence method for precise cross section measurements and develops a local optical potential to better match experimental data.

Findings

Gamma-gamma coincidence method effectively measures microbarn cross sections.

Standard models poorly reproduce the measured cross sections.

A tailored optical potential improves the description of the data.

Abstract

The reaction 141Pr(alpha,n)144Pm was investigated between E_alpha=11 MeV and 15 MeV with the activation method using the gamma-gamma 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 gamma-gamma coincidence method is an excellent tool to investigate cross sections down to the microbarn range. The (alpha,n) reaction at low energy is especially suited to test alpha+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 (gamma,alpha) rates for 145Pm and 148Gd were explored. In summary, the data and further results underline the problems in global predictions of alpha+nucleus optical potentials at astrophysically relevant energies.