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The energy of the first excited state in the neutron-rich N=28 nucleus 45Cl has been established via in-beam gamma-ray spectroscopy following proton removal. This energy value completes the systematics of the E(1/2^+_1)-E(3/2^+_1) level spacing in odd-mass K, Cl and P isotopes for N=20-28. The results are discussed in the framework of shell-model calculations in the sd-fp model space. The contribution of the central, spin-orbit and tensor components is discussed from a calculation based on a proton single-hole spectrum from G-matrix and pi + rho meson exchange potentials. A composite model for the proton 0d_{3/2}-1s_{1/2} single-particle energy shift is presented., Comment: Phys. Rev. C, in press

The collectivity of the odd-mass nucleus 55 Ni was explored via intermediate-energy Coulomb excitation using a powerful combination of particle and g -ray spectroscopy. A g -ray at 2879 ( 18 ) keV was observed and is interpreted to deexcite a member of the core-coupled quintuplet 2 1 + s 56 Ni d ^ n f 7/2 −1 at the same energy. By similarity with the mirror nucleus 55 Co, transition probabilities were calculated assuming J p =9/2 − and J p =11/2 − for this state. Both assumptions lead to a transition strength higher than predicted by a large-scale shell-model calculation using the GXPF1 effective interaction and exceed the value predicted within a simple weak-coupling approach ispartof: Physical Review C, Nuclear Physics vol:70 issue:6 status: published