A theoretical study of core-polarisation effects on E2 transitions in mass-19 nuclei and in the 19F(p, p′) 19F reaction

Abstract

First-order core-polarisation corrections are applied to full intermediate-coupling wave functions of the mass-19 system in a calculation of E2 transition rates. The theoretical E2 strengths are found to be smaller than those measured experimentally by a factor which varies between about 1 and 2 depending on the particular transition. The calculation is performed by first calculating a set of spectroscopic amplitudes which contain all the “one-body” information of the nuclear states. The same spectroscopic amplitudes are used in a DWBA calculation of the 19F(p, p') 19F reaction in which the effective density-dependent interaction of Pandharipande is used for the projectile target-nucleon interaction. The importance of using fully antisymmetrised DWBA matrix elements and also of including core-polarisation effects are clearly evident. Excellent theoretical fits for angular distributions of inelastically scattered protons from the lowest members of the ground-state rotational band are obtained. The theoretical cross sections must be normalised by similar factors to those required to bring the calculated E2 transition strengths into agreement with experiment, thus indicating the suitability of the interaction used.