Studies of the electric dipole transition of deformed rare-earth nuclei

Spectrum and electric dipole transition rates and relative intensities in S m152-154, Gd156-160, Dy160-162 are studied in the framework of the interact ing boson model with s,p,d,f, bosons. It is found that El transition data a mong the low-lying levels are in good agreement with the SU(3) dynamical sy mmetry of the spdf interacting boson model proposed by Engel and Iachello t o describe collective rotation with octupole vibration. These results show that these nuclei have SU(3) dynamic symmetry to a good approximation. Also in this work many algebraic expressions for electric dipole transitions in the SU(3) limit of the spdf-IBM have been obtained. These formulae togethe r with the formulae given previously exhaust nearly all the E1 transitions for low-lying negative parity states. They are useful in analyzing experime ntal data. (C) 1999 Elsevier Science B.V. All rights reserved.