Abstract
Background: is a neutron-deficient isotope with a -decay half-life of 298 ms and a spin and parity of . Previous measurements of -delayed rays have yielded a -decay scheme with twelve -decay transitions, contributing to studies of nuclear structure and fundamental symmetries. Those experiments have been limited to the observation of states with .
Purpose: Our goal is to search for new -delayed rays and -decay transitions of to .
Methods: A measurement of -delayed 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 -delayed -ray spectrum to date and exploiting a new sensitivity to coincidences, this experiment has enabled the observation of nine previously unobserved -delayed -ray transitions, leading to the inference of five -decay transitions never before observed in -delayed 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 have been determined. In addition, the resonance strength of the 9650-keV state has been limited to meV, which is an improvement over direct measurements.
Conclusion: An enhanced decay scheme has been constructed. Most of the excited bound states that would correspond to allowed and first-forbidden -decay transitions have been observed, demonstrating the potential of -decay experiments to approach complete spectroscopy measurements at the next generation of radioactive beam facilities. The observed positive-parity levels are well matched by shell-model calculations.
3 More- Received 30 March 2018
DOI:https://doi.org/10.1103/PhysRevC.98.024309
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