Spectroscopic study of the exotic nucleusP25

Abstract

Motivated by the importance of $^{25}\mathrm{P}$ for the two-proton decay of $^{26}\mathrm{S}$ and for searches of the mirror analog of the island of inversion near $N=16$, we present the first predictions for the spectroscopy of the exotic isotope $^{25}\mathrm{P}$ obtained in the shell model, a potential model, and a microscopic-cluster model. All models predict $^{25}\mathrm{P}$ to be unbound, with an energy in the range $0.78--1.03$ MeV, which favors previous mass systematics over more recent revisions. We show that $^{25}\mathrm{P}$ possesses a rich low-lying spectrum that should be accessible by experimental studies. All of the predicted states below 7 MeV, except one, are narrow. Many of them are built on the excited-core states of ${}^{24}\mathrm{Si}$ for which the Coulomb barrier is raised. For decays into the ${}^{24}\mathrm{Si}(\text{g.s.})+p$ channel we determined the proton widths based on their link to the asymptotic normalization coefficients (ANCs) of their mirror analogs in ${}^{25}\mathrm{Ne}.$ We determine these ANCs from the analysis of the transfer reaction ${}^{24}\mathrm{Ne}{(d,p)}^{25}\mathrm{Ne}$. The proton widths for decay into excited-state channels are obtained in model calculations. The only broad state is the intruder $3/2{}^{\ensuremath{-}}$, the mirror analog of which has been recently observed in ${}^{25}\mathrm{Ne}.$ The ${}^{25}\mathrm{P}(3/{2}^{\ensuremath{-}})$ energy is lower than that in ${}^{25}\mathrm{Ne}$, suggesting that the island of inversion may persist on the proton-rich side. All excited states of $^{25}\mathrm{P}$ have at least two decay modes and are expected to populate variously the ${2}_{1,2}^{+}$ and ${4}^{+}$ states in ${}^{24}\mathrm{Si}$, which then decay electromagnetically.