Toward complete spectroscopy using β decay: The example of Cl 32 (βγ) S 32

E. Aboud, M. B. Bennett, C. Wrede, M. Friedman, 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, E. I. McNeice, Z. Meisel, W. J. Ong, P. D. O'Malley, S. D. Pain, C. J. Prokop, H. SchatzS. B. Schwartz, S. Suchyta, P. Thompson, M. Walters, X. Xu

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Background: Cl32 is a neutron-deficient isotope with a β-decay half-life of 298 ms and a spin and parity of Jπ=1+. Previous measurements of Cl32 β-delayed γ rays have yielded a β-decay scheme with twelve β-decay transitions, contributing to studies of nuclear structure and fundamental symmetries. Those experiments have been limited to the observation of S32 states with Jπ=0+,1+,2+. Purpose: Our goal is to search for new β-delayed γ rays and β-decay transitions of Cl32 to S32. Methods: A measurement of Cl32 β-delayed γ decay has been performed using the Clovershare array of high-purity germanium detectors at the National Superconducting Cyclotron Laboratory. Results: By acquiring the highest-statistics Cl32 β-delayed γ-ray spectrum to date and exploiting a new sensitivity to γ-γ coincidences, this experiment has enabled the observation of nine previously unobserved β-delayed γ-ray transitions, leading to the inference of five β-decay transitions never before observed in Cl32 β-delayed γ decay. The set of observed states includes negative-parity states for the first time. By combining the new information with data from previous work, the lifetimes and partial widths of the 8861- and 9650-keV states of S32 have been determined. In addition, the P31(p,α)Si28 resonance strength of the 9650-keV state has been limited to ωγ<9.8 meV, which is an improvement over direct measurements. Conclusion: An enhanced decay scheme has been constructed. Most of the excited bound S32 states that would correspond to allowed and first-forbidden β-decay transitions have been observed, demonstrating the potential of β-decay experiments to approach complete spectroscopy measurements at the next generation of radioactive beam facilities. The observed positive-parity levels are well matched by sd shell-model calculations.

Original languageAmerican English
Article number024309
JournalPhysical Review C
Issue number2
StatePublished - 15 Aug 2018
Externally publishedYes

Bibliographical note

Funding Information:
The authors gratefully acknowledge the NSCL operations staff for providing the beam. This work was supported by the US National Science Foundation under Grants No. PHY-1102511, No. PHY-1404442, No. PHY-1419765, and No. PHY-1431052; by the US Department of Energy, Office of Science under Grant No. DE-SC00106052; by the National Nuclear Security Administration under Grant No. DE-NA0000979; and by the Natural Sciences and Engineering Research Council of Canada. E.A. acknowledges support from the Lawrence W. Hantel Endowed Fellowship Fund, in Memory of Prof. Donald J. Montgomery.

Publisher Copyright:
© 2018 American Physical Society.


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