XXIX. Collective effects in nuclei of mass 18 and 19

Abstract

In an intermediate coupling shell model calculation for the nuclei of mass 18 and 19, Elliott and Flowers (1955) determined the positions of the low lying levels in the absence of any collective effects. They found, however that certain E2 transition rates in ¹⁷O and ¹⁹F could not be explained without collective motion and that the introduction of weak coupling of the Bohr and Mottelson (1953) type between the surface and the nucleons outside the ¹⁶O core gave simultaneous agreement in ¹⁷O and ^l9F. In this note we consider the effects of such weak coupling, and show that although it enhances the E2 transition rates in ¹⁹F by a factor of order 5, the changes in level positions and magnetic moment, are negligible.