Exploring the Collective Spin--Isospin Longitudinal Response of Nuclei with Coherent Pion Production in (3He, tπ +).

The SATURNE charge-exchange program explored the spin-isospin response of nuclei in the Δ region. New results on coherent pion production are presented. They give a precise measure of the spin longitudinal component of this response. This component is particularly interesting since theoretical models predict that attractive residual Δ -hole correlations in the longitudinal channel (pion exchange) softens the response.