Polarization effect induced by aligned particles on quadrupole moments

The effect of shape-fluctuation, which is induced by aligned particles, on the quadrupole matrix-elements (with ΔI=0, 1 and 2) is investigated. The signature dependence of B(E2; ΔI=1)-values in odd-A nuclei can be produced by the deviation of the original core-shape from axial symmetry (including the fluctuation of the core-shape), as well as by the polarization in the gamma degree of freedom induced by aligned particles. For smaller γ-values and an approximately half-filled j-shell the two mechanisms contribute coherently so as to make the signature dependence more conspicuous. (orig.)