Universität zu Köln

Heim, F., Scholz, P., Mayer, J., Mueller, M. and Zilges, A. (2020). Constraining nuclear properties in Mo-94 via a Nb-93(p, gamma)Mo-94 total cross section measurement. Phys. Rev. C, 101 (3). COLLEGE PK: AMER PHYSICAL SOC. ISSN 2469-9993

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Abstract

Background: The nucleosynthesis of the group of neutron-deficient p nuclei remains an unsolved puzzle in nuclear astrophysics. Among these nuclei, Mo-94 is one of the most abundant and is notoriously underproduced in theoretical network calculations. In these networks, the respective cross sections and reaction rates play a crucial role. Since many reactions of astrophysical relevance are not accessible in the laboratory, a global and robust theoretical framework is required to provide reliable predictions. Purpose: Extending the experimental database on the one hand and direct or indirect studies of the respective nuclear physics properties on the other hand are the key tasks of experimental nuclear astrophysics. For this purpose, total cross sections of the Nb-93(p, gamma)Mo-94 reaction have been measured at proton energies between 2.0 and 5.0 MeV. Methods: In-beam gamma-ray spectroscopy has been utilized to measure total cross sections. In general, the total cross sections depend strongly on the gamma-ray decay widths in Mo-94, which are derived from the gamma-ray strength function and the nuclear level density. In our analysis we use a Bayesian optimization analysis to disentangle the effects of the gamma-ray strength function and the nuclear level density in Mo-94. Results: The total cross-section results reveal a significant discrepancy with respect to formerly published values. We propose parametrizations for the nuclear level density in Mo-94 based on the microscopic level densities from Hartree-Fock-Bogoliubov calculations. Moreover, we present gamma-ray strength functions for the El and M1 mode in Mo-94 that reveal a low-energy enhancement for M1 radiation and agree nicely with previous results. Conclusions: A model-independent approach to study E1 and M1 strength functions has been presented. In general, radiative capture cross sections are a well-suited tool to constrain the reaction rates in reaction networks but also provide insight into the statistical gamma-ray behavior of atomic nuclei.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Heim, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Scholz, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mayer, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mueller, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Zilges, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-340440
DOI:	10.1103/PhysRevC.101.035807
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 PHOTON STRENGTH FUNCTIONS; P-PROCESS; REACTION-RATES; STELLAR NUCLEOSYNTHESIS; DATA SHEETS; S-PROCESS; R-PROCESS; PHYSICS; MODEL; ASTROPHYSICS Multiple languages Physics, Nuclear Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/34044