Universität zu Köln

Scholz, P., Wilsenach, H., Becker, H. W., Blazhev, A., Heim, F., Foteinou, V, Giesen, U., Muenker, C., Rogalla, D., Sprung, P., Zilges, A. and Zuber, K. (2020). New measurement of the Sm-144(alpha, gamma) Gd-148 reaction rate for the gamma process. Phys. Rev. C, 102 (4). COLLEGE PK: AMER PHYSICAL SOC. ISSN 2469-9993

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Abstract

Background: Most of the heavier p isotopes are believed to be produced in the gamma process whose reaction path crucially depends on the proton and alpha-particle penetrability at sub-Coulomb energies. Both nuclei of the samarium p-process chronometer, Sm-146 and Sm-144, are produced in the. process, and their initial abundance ratio is very sensitive to the (gamma, n) and (gamma, alpha) branching ratio on Gd-148. The Gd-148(gamma, alpha) Sm-144 reaction rate was measured roughly 20 years ago by means of the activation technique and its surprising results triggered adjustments to the global low-energy a+nucleus optical-model potentials (OMPs). Purpose: We want to take advantage of modern alpha-particle spectroscopy techniques in order to constrain the controversial previous results on the Gd-148(gamma, alpha) Sm-144 reaction rate. Method: The Gd-148(gamma, alpha) Sm-144 reaction rate has been determined by measuring the cross section of the reverse reaction Sm-144(alpha, gamma) Gd-148, applying the activation technique to the alpha decay of Gd-148. Targets have been irradiated at the cyclotron of the Physikalisch-Technische Bundesanstalt in Braunschweig, Germany. The alpha-particle spectroscopy has been carried out with a state-of-the-art low-background ionization chamber of the Technische Universitat Dresden, Germany. Results: Cross sections for the Sm-144(alpha, gamma) Gd-148 reaction have been measured between 10.66 and 12.66 MeV with much higher precision than in the previous measurement. The results agree with earlier results within their uncertainties. The statistical-model analysis has been carried out using the TALYS code on the basis of the latest parametrizations of alpha-OMPs. The best reproductions of the experimental results within the statistical model have been used to calculate the reaction rates. Conclusion: The values presented here suggest a steeper increase in the astrophysical S factor towards lower center-of-mass energies. Different parametrizations of the alpha-OMP were able to describe the experimental values sufficiently. Further measurements at energies below 11.0 MeV are suggested.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Scholz, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wilsenach, H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Becker, H. W. UNSPECIFIED UNSPECIFIED UNSPECIFIED Blazhev, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Heim, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Foteinou, V UNSPECIFIED UNSPECIFIED UNSPECIFIED Giesen, U. UNSPECIFIED UNSPECIFIED UNSPECIFIED Muenker, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Rogalla, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Sprung, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Zilges, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Zuber, K. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-314537
DOI:	10.1103/PhysRevC.102.045811
Journal or Publication Title:	Phys. Rev. C
Volume:	102
Number:	4
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 P-PROCESS; NUCLEAR-PHYSICS; STELLAR NUCLEOSYNTHESIS; SOLAR-SYSTEM; R-PROCESS; EARTH; NEODYMIUM; PROGRAM; SM-146; ASTROPHYSICS Multiple languages Physics, Nuclear Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/31453