In-beam γ-ray spectroscopy and lifetime measurements in the neutron-deficient phosphorus isotopes

The properties of the neutron-deficient phosphorus isotopes have prompted a number of experimental and theoretical studies with focuses on both nuclear structure and nuclear astrophysics. Here we present results from in-beam γ-ray spectroscopy experiments performed at the National Superconducting Cyclotron Laboratory with the high-efficiency CsI(Na) array CAESAR and the high-resolution segmented Ge array SeGA. A new level in the drip-line nucleus ²⁶P was observed, the energy of the dominant resonance in ²⁷P for the (p,γ) reaction rate was confirmed, and lifetimes of excited states in ²⁸P were measured for the first time. Shell-model calculations using the USDB-CDPN interaction were performed with the single-particle energy of the 1s_1/2 proton orbital lowered to reproduce the observed Thomas-Ehrman shifts and electromagnetic transition probabilities in ²⁸P and its mirror nucleus were compared.