Isospin structure of transitions in 17O from inelastic pion scattering at 164 MeV

Differential cross sections for inelastic scattering of π+ and π- from a cooled gas target, enriched in 17O (49.9%), were measured at an incident energy T/sub π/ = 164 MeV between theta/sub lab/ = 180 and 740. Data were also taken on a natural oxygen and an enriched 18O target (94.9%) to allow a subtraction of the 16O and 18O yields from the data taken with the 17O target. A microscopic distorted wave impulse approximation analysis of five collectively enhanced transitions to the lowest J/sup π/ = (3/2)-, (5/2)-, (7/2)-, (9/2)-, and (11/2)- states in 17O was performed using transition densities from three different models. The data were fitted best with transition densities derived from a large-space shell-model calculation; provided that their [LSJ] = [303], isoscalar parts were enhanced by a factor (1+2delta). Both the π+ and π- data for the five transitions in 17O and the transition to the 3- state in 16O (6.13 MeV) were fitted using a single polarization charge, delta. Evidence was found for E2 strength near 8 MeV and for M4 strength to two states at 15.7 and 17.1 MeV