Nuclear structure study with inelastic electron scattering from 27Al Original Research Article

A microscopic theory is employed to include the effects of higher configurations outside the sd-shell model space, which are called core-polarization effects to describe the inelastic electron scattering form factors for even-parity states of 27Al. Higher configurations are taking into account through first-order perturbation theory, which allows particle–hole excitations from the 1s- and 1p-shells core orbits to the higher 2s–1d and 1f–2p shells with 2ℏω excitations. It is shown that the core-polarization effects are essential in obtaining a reasonable description of the data with no adjustable parameters. The calculations based on the Wildenthal interaction for the sd-shell model space and on the modified surface delta interaction (MSDI) for the core-polarization effects.