OBSERVATION OF ISOBARIC ANALOG STATES IN PION SINGLE CHARGE EXCHANGE REACTIONS

Isobaric-analog-state transitions have been observed throughout the periodic table in the (..pi../sup +/,..pi../sup 0/) reaction. The forward-angle differential cross sections at T/sub ..pi../=98 MeV on targets of CH/sub 2/, /sup 7/Li, /sup 13/C, /sup 27/Al, /sup 58/Ni, /sup 90/Zr, /sup 120/Sn, and /sup 208/Pb are reported. The A dependence follows (N-Z)A/sup -4/3/, which is qualitatively understood in terms of a strong-absorption model. Optical-potential calculations which demonstrate the sensitivity to neutron density distributions and to the isospin dependence of higher-order dynamical effects are discussed.