Direct study of the alpha-nucleus optical potential at astrophysical energies using the 64Zn(p,alpha)61Cu reaction

TL;DR

This study uses the 64Zn(p,alpha)61Cu reaction to directly investigate the alpha-nucleus optical potential at energies relevant to astrophysics, revealing inaccuracies in commonly used global models.

Contribution

First experimental use of a (p,alpha) reaction to directly study the alpha-nucleus optical potential at astrophysical energies.

Findings

Measured cross sections are sensitive to the alpha-nucleus potential.

Global optical potentials used in models are shown to be inaccurate.

Provides direct experimental evidence for refining astrophysical reaction models.

Abstract

In the model calculations of heavy element nucleosynthesis processes the nuclear reaction rates are taken from statistical model calculations which utilize various nuclear input parameters. It is found that in the case of reactions involving alpha particles the calculations bear a high uncertainty owing to the largely unknown low energy alpha-nucleus optical potential. Experiments are typically restricted to higher energies and therefore no direct astrophysical consequences can be drawn. In the present work a (p,alpha) reaction is used for the first time to study the alpha-nucleus optical potential. The measured 64Zn(p,alpha)61Cu cross section is uniquely sensitive to the alpha-nucleus potential and the measurement covers the whole astrophysically relevant energy range. By the comparison to model calculations, direct evidence is provided for the incorrectness of global optical potentials used in astrophysical models.