Charge and Double Charge Exchange in Pion-Nucleus Scattering

Abstract

Angle-integrated excitation functions for single charge exchange (SCE) to discrete two-body final states for both analog (ΔT=0, ΔTz=1) and non-analog (ΔT=1, ΔTz=1) transitions are now available. There are also π± elastic and SCE angular distributions on 3He and 3H at several energies. Similarly, the first measurements of both (ΔT=0, ΔTz=2) and (ΔT=2, ΔTz=2) transitions for double charge exchange (DCE) to discrete two-body final states have also been made. There is no clear dominance of ΔT=0 analog transitions over ΔT≠0 transitions for either SCE or DCE although the results are confined to rather low mass nuclei. Comparison of very recent DCE results for different isotopes show some rather remarkable variations which indicate that these reactions provide a practical tool for both mass determinations and spectroscopic studies (e.g. ground state correlations) of nuclei far from the line of stability. Various calculations for these reactions based on multiple scattering theory are discussed for their use in interpreting the observations.