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:
CreatorsEmailORCIDORCID Put Code
Scholz, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Wilsenach, H.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Becker, H. W.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Blazhev, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Heim, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Foteinou, VUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Giesen, U.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Muenker, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Rogalla, D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Sprung, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Zilges, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Zuber, K.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
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:
KeywordsLanguage
P-PROCESS; NUCLEAR-PHYSICS; STELLAR NUCLEOSYNTHESIS; SOLAR-SYSTEM; R-PROCESS; EARTH; NEODYMIUM; PROGRAM; SM-146; ASTROPHYSICSMultiple languages
Physics, NuclearMultiple languages
URI: http://kups.ub.uni-koeln.de/id/eprint/31453

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