E1 transition rates in transitional 148–152Sm isotopes in the IBA-sdf model

The E1 transition rates in Sm isotopes with neutron number N =86−90 are studied in the frame of the (sd) N B−1 f interacting boson model. An effective E1 operator, obtained by eliminating, by perturbation theory, the p boson from the spdf model, explains very well the E1 data in this transitional region.