β-decay studies of neutron-rich K isotopes

Abstract

The \ensuremath{\beta} decay of the neutron-rich nuclei $^{51\ensuremath{-}53}\mathrm{K}$ has been used to populate bound and unbound states in $^{50\ensuremath{-}53}\mathrm{Ca}$. Measurements of \ensuremath{\gamma} rays as well as \ensuremath{\beta}-delayed neutrons enabled detailed decay schemes to be established and levels identified in ${}^{50\ensuremath{-}53}$Ca. A delayed one-neutron emission probability ${P}_{1n}$ of $63\ifmmode\pm\else\textpm\fi{}8$% was determined for the decay of $^{51}\mathrm{K}$. A total of seven new \ensuremath{\gamma} transitions were observed following the decay of $^{51}\mathrm{K}$, and 25 neutron branches were found that enrich the level scheme of $^{51}\mathrm{Ca}$. Delayed neutron emission probabilities of ${P}_{1n}=74.4\ifmmode\pm\else\textpm\fi{}9.3$% and ${P}_{2n}=2.3\ifmmode\pm\else\textpm\fi{}0.3$% were determined for the decay of $^{52}\mathrm{K}$, and 12 new \ensuremath{\gamma} transitions were observed in $^{50,51,52}\mathrm{Ca}$. Three new \ensuremath{\gamma} transitions were observed in $^{52,53}\mathrm{Ca}$ following the \ensuremath{\beta} decay of $^{53}\mathrm{K}$. New limits on the ${P}_{1n}$ and ${P}_{2n}$ values were determined for the \ensuremath{\beta} decay of $^{53}\mathrm{K}$, and a decay scheme was established for $^{53}\mathrm{Ca}$ for the first time. The data obtained here should help clarify the structure of neutron-rich $\mathit{fp}$-shell nuclei around the $N=32\text{\ensuremath{-}}34$ subshell closures.