# Spectroscopy and lifetime measurements near the proton drip line: $^{26,27,28}$P

## TL;DR

This study used gamma-ray spectroscopy to observe and measure excited states and lifetimes in neutron-deficient phosphorus isotopes near the proton drip line, providing new insights into their nuclear structure.

## Contribution

It reports the first observation of a level in $^{26}$P, new measurements of resonances in $^{27}$P, and lifetime determinations in $^{28}$P, advancing understanding of proton-rich nuclei.

## Key findings

- Discovery of a new level at 244 keV in $^{26}$P
- New measurements of the 3/2$^+$ resonance in $^{27}$P
- First lifetime measurements of excited states in $^{28}$P

## Abstract

We report on the observation of excited states in the neutron-deficient phosphorus isotopes $^{26,27,28}$P via in-beam gamma-ray spectroscopy with both high-efficiency and high-resolution detector arrays. In $^{26}$P, a previously-unobserved level has been identified at 244(3) keV, two new measurements of the astrophysically-important 3/2$^+$ resonance in $^{27}$P have been performed, gamma decays have been assigned to the proton-unbound levels at 2216 keV and 2483 keV in $^{28}$P, and the gamma-ray lineshape method has been used to make the first determination of the lifetimes of the two lowest-lying excited states in $^{28}$P. The expected Thomas-Ehrman shifts were calculated and applied to levels in the mirror nuclei. The resulting level energies from this procedure were then compared with the energies of known states in $^{26,27,28}$P.