Microscopic description of the M3 strength distribution in deformed nuclei

Abstract

The modified version of the RPA is developed in which multipole and magnetic spin-multipole interactions are taken into account. The mathematical apparatus for the description of the fragmentation of the RPA phonons due to coupling with 2p2h configurations is presented. The M3 strength distribution in 164Dy and 168Er is calculated in the RPA with the multipole and spin-multipole magnetic interactions. The inclusion of the spin-octupole interaction in addition to multipole ones reduced 2–10 times B(M3) values for the states with energies up to 6 MeV. The spin part of the M3 transition operator dominates if the constants of spin-octupole interactions κ 22 κ = 0. The orbital part of the reduced probabilities of the M3 transitions to K π = 2 + and 3 + states gives less than 40% and to K π = 1 + states about 50% at κ 23 κ = −0.024 fm 2 MeV. Fragmentation of one-phonon states due to coupling with 2p2h configurations in 164Dy and 168Er is calculated. One-phonon states with energies below 4 MeV are not too strongly fragmented. We predict the concentration of the M3 strength in some energy range in 164Dy and 168Er for experimental observation. These energy ranges are independent of a spin-octupole interaction. The K π = 1 + one-phonon states with large B(M1) values in 164Dy are weakly fragmented. Most of the one-phonon states at energies from 4 to 6 MeV are strongly fragmented.