Abstract
Background: is the most abundant nucleus of the nuclei, with an isotopic abundance of more than 14 %. The nucleosynthesis is believed to produce but fails to explain its large abundance, especially with respect to the other nuclei produced in the same stellar environment. Further studies require precise nuclear models for the calculation of reaction cross sections.
Purpose: A measurement of the total and partial cross sections of the reaction allows for a stringent test of statistical-model predictions. Not only different optical model potentials, but also the strength function of can be investigated. In addition, high-resolution in-beam spectroscopy enables the determination of new precise nuclear structure data for .
Method: Total and partial cross-section values were measured by using the in-beam method. Prompt rays emitted during the irradiation of with protons at seven different energies between 3.7 and 5.3 MeV were detected by using the high-purity germanium (HPGe) detector array HORUS at the Institute for Nuclear Physics, University of Cologne. The method was applied to correlate cascades in with their origin in the compound state.
Results: The measured cross sections are compared to Hauser–Feshbach calculations by using the statistical-model code talys on the basis of different nuclear physics input models. Using default settings based on standard phenomenological models, the experimental values cannot be reproduced. A shell-model calculation was carried out to predict the low-energy strength in . Together with Gogny–Hartree–Fock–Bogoliubov (Gogny-HFB) or Skyrme-HFB plus quasi-particle random-phase approximation (QRPA) models for the strength function, the agreement between experimental data and theoretical predictions could be significantly improved. In addition, deviations from the adopted level scheme were found.
Conclusions: By using Gogny- or and shell-model strength functions, statistical-model predictions can be significantly improved. Partial cross sections provide a valuable testing ground for strength functions for nuclear astrophysics applications. In addition, they can be used to investigate nuclear-structure properties of the compound nucleus.
3 More- Received 28 November 2015
DOI:https://doi.org/10.1103/PhysRevC.93.045809
©2016 American Physical Society