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β decay of neutron-rich Ca 53 − 56

2008; American Institute of Physics; Volume: 77; Issue: 1 Linguagem: Inglês

10.1103/physrevc.77.014313

1538-4497

P. F. Mantica, R. Broda, H. L. Crawford, A. Damaske, B. Fornal, A. A. Hecht, C. R. Hoffman, Mihai Horoi, N. Hoteling, R. V. F. Janssens, J. Pereira, J. S. Pinter, J. Stoker, S. L. Tabor, T. Sumikama, W. B. Walters, X. Wang, S. Zhu,

Nuclear Physics and Applications

\ensuremath{\beta}-decay properties of neutron-rich Ca isotopes have been obtained. Half-life values were determined for the first time for $^{54}\mathrm{Ca}$ ($86\ifmmode\pm\else\textpm\fi{}7$ ms), $^{55}\mathrm{Ca}$ ($22\ifmmode\pm\else\textpm\fi{}2$ ms), and $^{56}\mathrm{Ca}$ ($11\ifmmode\pm\else\textpm\fi{}2$ ms). The half-life of $230\ifmmode\pm\else\textpm\fi{}60$ ms deduced for $^{53}\mathrm{Ca}$ is significantly longer than reported previously, where the decay chain $^{53}\mathrm{K}$ \ensuremath{\rightarrow} $^{53}\mathrm{Ca}$ \ensuremath{\rightarrow} $^{53}\mathrm{Sc}$ was considered. A delayed \ensuremath{\gamma} ray with an energy of 247 keV was identified following \ensuremath{\beta} decay of $^{54}\mathrm{Ca}$ and is proposed to depopulate the ${1}_{1}^{+}$ level in $^{54}\mathrm{Sc}$. The \ensuremath{\beta}-decay properties compare favorably with the results of shell-model calculations completed in the full $\mathit{pf}$ space with the GXPF1 interaction. The half-lives of the neutron-rich Ca isotopes are also compared with gross \ensuremath{\beta}-decay theory. The systematic trend of the neutron-rich Ca half-lives is consistent with the presence of a subshell gap at $N=32$.