Stretched spin strength in 26Mg and 30Si.

Abstract

Calculations have been made to explore the effect of configuration mixing in a large basis on the fragmentation of stretched'' [ital M]6 strength in the [ital sd]-shell nuclei [sup 26]Mg and [sup 30]Si. This work extends a study made for [ital N]=[ital Z] [ital sd]-shell nuclei to midshell [ital N][ne][ital Z] nuclei with the same Hamiltonian and basis restriction, one particle in the 1[ital f][sub [tau]/2] orbit and unrestricted occupancy of the [ital sd]-shell orbits, used in that earlier work. It is found that configuration mixing in this large basis gives a very good description of the total isovector strength seen in [sup 26]Mg but fails to give a detailed description of the experimental spectra. Results for fragmentation of the isoscalar response are less conclusive because of conflicts between data sets.