Toward a microscopic description of theM1 states in deformed even-odd nuclei

Abstract

The magnetic dipole collective excitation, known as scissors mode, is studied in odd deformed nuclei within the framework of a particle-core coupling scheme. The description is made in the intrinsic and laboratory frames. In both frames the core is described in the RPA approach by a schematic many body Hamiltonian. In the intrinsic frame we use an effective particle-core Hamiltonian which is treated perturbatively. In the laboratory frame two K = 1/2 triplets with J = 1/2, 3/2, 5/2 are constructed through projection from two intrinsic excited states respectively. Each member of these multiplets are collectively M1 excited from the state (K, J~)=(3/2, 3/2+). Their energies are obtained by averaging a rotationally invariant Hamiltonian. Another multiplet with K = 3/2 and J=3/2, 5/2, which is strongly coupled to the state (K, J~)=(5/2, 5/2 +) through a M1 transition, is described. These results indicate that the M1 collective excitation should exist also in odd deformed nuclei.

Scissors mode and effects of the low-lying E1 excitations on the dipole distributions in 175Lu

“…Although the low-lying dipole excitations have also been observed in several odd-mass deformed nuclei [15][16][17][18][19][20][21][22][23][24][25][26][27][28], a limited number of theoretical attempts have been made to explore the nature and the systematics of these excitations. Pioneering calculations performed using the schematic and phenomenological models [29][30][31][32][33][34][35][36][37][38][39] reveal the existence of low-lying dipole strength in odd-mass nuclei but fail to explain the extreme fragmentation observed in dipole spectra. The intense fragmentation has only been reproduced through microscopic model calculations such as the QPM of Soloviev et al [37,38].…”

Microscopic description of the scissors mode in odd-mass heavy deformed nuclei

“…Theoretical descriptions of scissors modes in odd-mass nuclei have been offered within the context of the IBFM [12,13], the particle-core-coupling model [14] and the QPNM [15]. While the different models agree in relating the presence of the uncoupled nucleon with the * Electronic address: vargas@ganil.fr † Electronic address: hirsch@nuclecu.unam.mx ‡ Electronic address: draayer@lsu.edu observed fragmentation, the detailed description of this mode, with a nearly flat spectrum in some nuclei and has well-defined peaks in others is still not understood.…”