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 1s1_/2 proton orbital lowered to reproduce the observed Thomas-Ehrman shifts and electromagnetic transition probabilities in ²⁸P and its mirror nucleus were compared.

This work was supported by the NSF under Grants No. PHY-1102511 and No. PHY1565546, by the DOE NNSA through the NSSC, under Award No. DE-NA0003180, and by the DOE, Office of Nuclear Physics, under Grant No. DEFG02-08ER41556. B.A.B. acknowledges support from NSF Grant No. PHY-1404442. W.A.R. is supported by the National Research Foundation of South Africa Grant No. 105608.