Low-lying magnetic and electric dipole strength distribution in the Hf-176 nucleus

Abstract

In this study the QRPA approach with the rotational and translational invariant Hamiltonians has been carried out to describe magnetic and electric dipole excitations in Hf-176. Calculations show that the Hf-176 nucleus demonstrates a very rich B( M1) strength structure and in some aspects nicely confirm the experimental data. It has been shown that the main part of spin-1 states, observed at 2-4 MeV in Hf-176, may be attributed to have a M1 character and may be interpreted as the main fragments of the scissors mode. The agreement between the calculated mean excitation energies as well as the summed B( M1) values of the scissors mode excitations and the available experimental data is quite good. The constructive interference between the orbit and the spin part of M1 strength has been found to be below 3.5 MeV. The calculations indicate the presence of a few prominent negative-parity K-pi = 1(-) states in the 2-4 MeV energy interval. This suggests that the supposition of the experiment "all stronger Delta K = 1 low-lying dipole excitations were of magnetic character" cannot be generalized.