Low energy orbital magnetic dipole excitations of heavy nonspherical nuclei

Abstract

To clarify the physical nature of the orbital magnetic dipole excitations discussed widely in the past few years, a semiclassical model is presented and the nuclei a56Gd and 164Dy are investigated microscopically. The semiclassical model involves a consistent treatment of vibrational and rotational degrees of freedom; the microscopic results are obtained in quasiparticle-random-phase approximation (QRPA) with a realistic effective interaction. The results disagree with the picture of scissors modes or rotational vibrations.

The nuclear scissors mode from various aspects

“…This agrees with the conclusion of the papers [14,15]: classically (i.e., without Fermi surface deformation) the scissors mode is a zero energy mode.…”

Scissors Modes and Spin Excitations in Light Nuclei IncludingΔN=2 Excitations: Behaviour of8Be and10Be

“…Also the J=4 + state has not been found. There is additional information obtained by looking at 10 C and 10 B. In 10 C, which is the mirror nucleus of 10 Be, the 2 10 Li has recently been produced by Kryger et al [15] and studied by M. Zinser et al [16].…”

“…In even even nuclei, all of which have J=0 + ground sates, the scissors modes have quantum numbers J=1 strength for 0 Ä 2 transitions (alternately that orbital B(M1) is proportional to $ 2 , where $ is the deformation parameter). Another topic of interest is the possibility of finding scissors mode strength at about 2 | excitations as has been emphasized by Speth and Zawischa [9,10]. This follows from the fact that there is considerable B(E2) strength in that vicinity i.e.…”

“…In N{Z nuclei much of the scissors mode strength can reside in states with the same isospin as the ground state. Thus in this work we will also consider 10 Be, where the ground state has quantum numbers J=0 + T=1, and where there are two scissors branches J=1 + T=1 and J=1 + T=2.…”

“…Furthermore most light nuclei e.g. 8 Be and 10 Be are strongly deformed and so should be favorable to the existence of easily identifiable scissors mode excitations.…”