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