Abstract
Background: 32Cl 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 32Cl 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 32S states with Jπ=0+,1+,2+.
Purpose: Our goal is to search for new β-delayed γ rays and β-decay transitions of 32Cl to 32S.
Methods: A measurement of 32Cl 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 32Cl 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 32Cl 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 32S have been determined. In addition, the 31P(p,α)28Si 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 32S 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.
