${}^{25}$Si ${\beta }^{+}$-decay spectroscopy

Abstract

$\beta$-decay spectroscopy provides valuable information on exotic nuclei and a stringent test for nuclear theories beyond the stability line. To search for new $\beta$-delayed protons and $\gamma$ rays of ${}^{25}$Si to investigate the properties of ${}^{25}$Al excited states. ${}^{25}$Si $\beta$ decays were measured by using the Gaseous Detector with Germanium Tagging system at the National Superconducting Cyclotron Laboratory. The protons and $\gamma$ rays emitted in the decay were detected simultaneously. A Monte Carlo method was used to model the Doppler broadening of ${}^{24}$Mg $\gamma$-ray lines caused by nuclear recoil from proton emission. Shell-model calculations using two newly developed universal \textit{sd}-shell Hamiltonians, USDC and USDI, were performed. The most precise ${}^{25}$Si half-life to date has been determined. A new proton branch at 724(4)~keV and new proton-$\gamma$-ray coincidences have been identified. Three ${}^{24}$Mg $\gamma$-ray lines and eight ${}^{25}$Al $\gamma$-ray lines are observed for the first time in ${}^{25}$Si decay. The first measurement of the ${}^{25}$Si $\beta$-delayed $\gamma$ ray intensities through the ${}^{25}$Al unbound states is reported. All the bound states of ${}^{25}$Al are observed to be populated in the $\beta$ decay of ${}^{25}$Si. Several inconsistencies between the previous measurements have been resolved, and new information on the ${}^{25}$Al level scheme is provided. An enhanced decay scheme has been constructed and compared to the mirror decay of ${}^{25}$Na and the shell-model calculations. The measured excitation energies, $\gamma$-ray and proton branchings, log~$ft$ values, and Gamow-Teller transition strengths for the states of ${}^{25}$Al populated in the $\beta$ decay of ${}^{25}$Si are in good agreement with the shell-model calculations, offering gratifyingly consistent insights into the fine nuclear structure of ${}^{25}$Al.

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Cited by in corpus (3)

• Constraining the ${}^{30}$P($p,\gamma {)}^{31}$S reaction rate in ONe novae via the weak, low-energy, $\beta$-delayed proton decay of ${}^{31}$Cl
• Time Projection Chamber for GADGET II
• Extension of the particle x-ray coincidence technique: The lifetimes and branching ratios apparatus