ISOSPIN DEPENDENCE OF KINETIC ENERGIES IN LIGHT NEUTRON-RICH NUCLEI

Energy spectra and electric-dipole transitions of N = 7 isotones are studied by shell-model calculations with isospin-dependent kinetic energies for sd-shell orbits. Our model is designed to reproduce the parity-inverted spectra near the ground state of Be-11. The ground states of Li-10 and He-9 are predicted to have abnormal parities as a result of a smooth isospin dependence of kinetic energies. Electric-dipole transitions in C-13 and Be-11 are also studied by using the calculated shell-model spectroscopic factors with realistic single-particle wave functions in the Woods-Saxon potential. Calculated transition strengths have a magnitude of the Weisskopf unit, and show good agreement with experimental data. The microscopic origin of the isospin-dependent kinetic energies is discussed in relation with Hartree-Fock single-particle energies.