Abstract
We perform large-scale shell-model calculations of -decay properties for neutron-rich nuclei with and , taking the first-forbidden transitions into account. The natural-parity and unnatural-parity states are calculated in the and model spaces, respectively, within the full valence shell. The calculated -decay half-lives and -delayed neutron emission probabilities show good agreement with the experimental data. The first-forbidden transitions make a non-negligible contribution to the half-lives of nuclei. The low-lying Gamow-Teller strengths of even-even nuclei are considerably larger than those of the neighboring odd- and odd-odd nuclei, strongly affecting the half-lives and neutron emission probabilities. It is shown that this even-odd effect is caused by the proton-neutron pairing interaction. We derive a formula to represent the positions of the Gamow-Teller giant resonances from the calculated strength distributions.
4 More- Received 13 March 2018
DOI:https://doi.org/10.1103/PhysRevC.97.054321
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