Enhanced and quenched B(E1) transition rates between parity doublet bands in Ra-227

The fast timing beta gamma gamma(t) method has been used to measure level lifetimes in the parity doublet bands in Ra-227 populated in the beta(-) decay of Fr-227. In particular, T-1/2 = 254(9) ps, 236(30) ps, less than or equal to 41 ps and 16(13) ps have been measured for the 3/2(-) and 5/2(-) members of the K-pi = 3/2(-) band and for the 1/2(-) and 3/2(-) members of the K-pi = 1/2(-) band, respectively. These results indicate surprisingly fast B(E1) rates in this octupole transitional nucleus with the average \D-0\ value of greater than or equal to 0.11 e . fm for the K-pi = 1/2(-) band and \D-0\ = 0.10 e . fm for K-pi = 3/2(-) band. The general enhancement (and occasional quenching) of E1 intra-doublet and some enhanced extra-doublet transitions in Ra-227 are interpreted within the quasiparticle-plus-phonon model with the inclusion of Coriolis coupling. Similar calculations, performed for Ra-223, are found to be in good agreement with the experimental data.