PION DOUBLE-CHARGE-EXCHANGE ON O-16 AT T-PI = 300-500 MEV

Measurements of small-angle cross sections for the pion double-charge- exchange (DCX) reaction O-16(pi+,pi-)Ne-16(g.s.) at incident energies of 300-500 MeV are reported. These are the first measurements of DCX c ross sections on a T = 0 nucleus in this energy region. The behavior o f the cross sections is similar to that of analog transitions, but the y are smaller by more than an order of magnitude. This suggests sequen tial charge-exchange scattering as the dominant process, but suppresse d by a mechanism not yet identified.