Shears mechanism in Cd-109 - art. no. 034318

Lifetimes of high-spin states in two Delta I=1 bands and one Delta I=2 band in Cd-109 have been measured using the Doppler shift attenuation method in an experiment performed using the Zr-96(O-18,5n) reaction with the GAMMASP HERE array. Experimental total angular momenta and reduced transition stren gths for both Delta I=1 bands were compared with tilted axis cranking (shea rs mechanism) predictions and the Delta I=2 band with principal axis cranki ng predictions, based on configurations involving two proton g(9/2) holes a nd one or three valence quasineutrons from the h(11/2) and mixed g(7/2)/d(5 /2) orbitals. Good overall agreement for angular momentum versus rotational frequency has been observed in each case. The Delta I=2 band is shown to h ave a large J((2))/B(E2) ratio suggestive of antimagnetic rotation. Additio nally, both dipole bands show a decreasing trend in B(M1) strength as a fun ction of spin, a feature of the shears mechanism. The experimental results are also compared with a semiclassical model that employs effective interac tions between the proton holes and neutrons as an alternate interpretation for the shears mechanism.