Detailed study of the decay Cl 31 (βγ) S 31

M. B. Bennett, C. Wrede, S. N. Liddick, D. Pérez-Loureiro, D. W. Bardayan, B. A. Brown, A. A. Chen, K. A. Chipps, C. Fry, B. E. Glassman, C. Langer, N. R. Larson, E. I. McNeice, Z. Meisel, W. Ong, P. D. O'Malley, S. D. Pain, C. J. Prokop, H. Schatz, S. B. SchwartzS. Suchyta, P. Thompson, M. Walters, X. Xu

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Background: Cl31 is a neutron-deficient isotope with a half-life of T1/2=190(1) ms. The nuclear structure of its daughter, S31, is important for the determination of the thermonuclear P30(p,γ)S31 reaction rate, which affects the final isotopic abundances of the ejecta from classical oxygen-neon novae. Purpose: We aim to determine the β feedings, γ-decay branchings, and excitation energies of states populated in S31 and create a comprehensive decay scheme for comparison with predictions based on the shell model. Methods: Using a Cl31 rare istope beam implanted into a plastic scintillator and an array of high-purity Ge detectors, γ rays from the Cl31(βγ)S31 decay sequence were measured. Shell-model calculations using the USDB and the recently-developed USDE interactions were performed for comparison. Results: A Cl31 β-decay scheme was constructed from the experimental data and compared to the USDB and USDE shell-model calculations based on the β feeding and γ-decay branches of each observed state. 33 new γ-ray transitions and ten new β decay branches were observed. The β feeding and γ-decay branches of each observed state were compared to those from the USDB and USDE shell-model calculations. For every allowed transition predicted by the USD calculations up to an excitation energy of 6.4 MeV in S31, an analogous transition was found in the experimental data, enabling a one-to-one comparison with the shell model. Using these identifications, spin and parity arguments were made for observed states. Conclusions: The new Cl31 γ-decay scheme presented in this work is the most complete and precise one for this nucleus constructed to date, incorporating statistics over an order of magnitude higher than previous work on Cl31 β-delayed γ decay. Of particular interest is the discovery of a 6390-keV state that mixes with the isobaric analog state and affects the P30(p,γ)S31 reaction rate. Other states observed in the decay are not expected to strongly affect the P30(p,γ)S31 reaction rate, but the comprehensive comparison to the shell model helps to clarify spin and parity assignments of resonances that might affect the rate.

Original languageEnglish
Article number065803
JournalPhysical Review C
Volume97
Issue number6
DOIs
StatePublished - Jun 14 2018

Funding

We gratefully acknowledge the dedicated effort of the NSCL operations staff to ensure the delivery of multiple very pure beams. This work was supported by the US National Science Foundation under Grants No. PHY-1102511, No. PHY-1404442, No. PHY-1419765, and JINA Grant No. PHY-1430152; by the US Department of Energy, National Nuclear Security Administration under Grant No. DE-NA0000979; by the US Department of Energy, Office of Science, under Grant No. DE-SC0016052; and by the Natural Sciences and Engineering Research Council of Canada. We also gratefully acknowledge use of the Clovershare array.

FundersFunder number
Clovershare array
US Department of Energy
US National Science FoundationPHY-1430152
National Science Foundation1713857
Office of ScienceDE-SC0016052
National Nuclear Security AdministrationDE-NA0000979
Natural Sciences and Engineering Research Council of Canada
Jinan University
National Science FoundationPHY-1419765

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