One-loop analysis of the reaction piN -> pipiN

The electromagnetic properties of low-excitation states in (191)Ir and (193)Ir have been studied following Coulomb excitation. Gyromagnetic ratios were measured by the transient-field technique and level lifetimes were measured by the Doppler-shift recoil distance method. Multipolarity mixing ratios were determined from measured particle- gamma angular correlations. The present lifetime and g-factor results extend the data available for comparison with theory and help discriminate between disparate experimental values reported previously in the literature. We compare the experimental data with particle-triaxial-rotor model calculations and with the predictions of the U(6/4) and U7(6/20) supersymmetry models based on the interacting-bosonfermion model.