Universität zu Köln

Heim, F., Scholz, P., Koerschgen, M., Mayer, J., Mueller, M. and Zilges, A. (2020). Insights into the statistical gamma-decay behavior of Cd-108 via radiative proton capture. Phys. Rev. C, 101 (3). COLLEGE PK: AMER PHYSICAL SOC. ISSN 2469-9993

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Abstract

Background: For the description of many astrophysical processes, precise knowledge of cross sections and reaction rates is necessary. In particular, the exact nucleosynthesis mechanisms of the p nuclei-a group of 30 to 35 neutron deficient nuclei-are still unknown. Since many reactions of astrophysical relevance are not accessible in the laboratory, one has to rely on theoretical calculations based on Hauser-Feshbach codes. The calculated values depend strongly on nuclear physics input parameters like nuclear level densities (NLDs), gamma-ray strength functions (gamma-SFs) and particle+nucleus optical model potentials (OMPs). Purpose: Measuring the Ag-107(p, gamma) Cd-108 reaction cross section at sub-Coulomb energies extends the scarce experimental database. In particular, partial cross sections yield important information about the gamma-SF in Cd-108. Via the comparison of total (p, gamma) cross sections to theoretical calculations, a locally adopted NLD model was found. Method: Highly enriched Ag-107 targets were bombarded with protons at six different beam energies between 2.0 and 5.0 MeV. The reaction yield and thus the reaction cross section were determined via in-beam y -ray spectroscopy using the HORUS gamma-ray spectrometer. Total (p, gamma) cross sections were obtained by the observation of ground-state transitions in Cd-108 and partial cross sections via the analysis of primary gamma-ray transitions into different excited states in Cd-108. Results: Cross-section values at six energies close to the astrophysical relevant energy region were determined. The slight adjustment of microscopic models for the NLD to the total (p, gamma) cross sections, respectively the dipole strength function to the partial cross sections, yielded an excellent agreement between the experimentally determined results and statistical model calculations. Conclusion: The obtained results help to constrain the nuclear physics input for statistical model calculations and hence to improve the precision of the theoretical determination of reaction rates. In particular, information about the p nucleus Cd-108 helps us to understand the mechanisms of the p process.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Heim, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Scholz, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Koerschgen, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mayer, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mueller, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Zilges, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-340750
DOI:	10.1103/PhysRevC.101.035805
Journal or Publication Title:	Phys. Rev. C
Volume:	101
Number:	3
Date:	2020
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	2469-9993
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language LEVEL DENSITY; P-PROCESS; STRENGTH FUNCTION; NUCLEAR-PHYSICS; NEUTRON-CAPTURE; CROSS-SECTIONS; MASSIVE STARS; STELLAR NUCLEOSYNTHESIS; REACTION-RATES; S-PROCESS Multiple languages Physics, Nuclear Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/34075