R. D. Lawson

Inelastic pion scattering from O 18

The inelastic scattering of 164 MeV pions from /sup 18/O is studied using the distorted-wave impulse approximation in momentum space. The sensitivity of the predictions to various shell model descriptions of the yrast 2/sup +/ state is examined in detail. The excitation of the triplet of states (4/sup +//sub 1/, 0/sup +//sub 2/, 2/sup +//sub 2/) near 3.7 MeV and the (3/sup -//sub 1/, 0/sup +//sub 3/, 2/sup +//sub 3/) triplet at about 5.2 MeV are also investigated within the context of the shell model. In order to explain the scattering to natural parity states (those with angular momentum J and parity (-1)/sup J/), one must enhance the theoretical results by about the same factor as needed to explain the B (EJ; 0 ..-->.. J) transition rates obtained from electromagnetic excitation. The sensitivity of the results to the isoscalar or isovector character of this enhancement is examined. Agreement between distorted-wave impulse approximation calculations and experiment is found to be satisfactory.

Isospin mixing in F 19

Isospin mixing in the yrast I = 5/2/sup +/ T = 1/2 level has been calculated assuming an isoscalar nucleon-nucleon interaction and the single-particle level spacings observed in /sup 17/O and /sup 17/F. Results are presented for both the (d/sub 5/2/,s/sub 1/2/) and two variants of the (d/sub 5/2/,s/sub 1/2/,d/sub 3/2/) model spaces. The experimental value does not require the introduction of a charge symmetry or charge independence breaking nucleon-nucleon interaction.

Extensive momentum‐space DWIA studies of pion‐nucleus inelastic scattering

Within the framework of DWIA, we have carried out extensive studies of pion‐nucleus inelastic scattering. Our objectives are: (a) to examine critically the extent to which the DWIA method can be valid, (b) to explore nuclear structure from the recent experimental data.