Carlos E. Vargas

Pseudo SU(3) shell model: Normal parity bands in odd-mass nuclei

Abstract A pseudo shell SU(3) model description of normal parity bands in 159Tb is presented. The Hamiltonian includes spherical Nilsson single-particle energies, the quadrupole–quadrupole and pairing interactions, as well as three rotor terms. A systematic parametrization is introduced, accompanied by a detailed discussion of the effect each term in the Hamiltonian has on the energy spectrum. Yrast and excited band wavefunctions are analyzed together with their B(E2) values.

Quasi-SU(3) truncation scheme for even–even sd-shell nuclei

The Quasi-SU(3) symmetry was uncovered in full pf and sdg shell-model calculations for both even-even and odd-even nuclei. It manifests itself through a dominance of single-particle and quadrupole-quadrupole terms in the Hamiltonian used to describe well-deformed nuclei. A practical consequence of the quasi-SU(3) symmetry is an efficient basis truncation scheme. In a recent work was shown that when this type of Hamiltonian is diagonalized in an SU(3) basis, only a few irreducible represntations (irreps) of SU(3) are needed to describe the Yrast band, the leading S = 0 irrep augmented with the leading S = 1 irreps in the proton and neutron subspaces. In the present article the quasi-SU(3) truncation scheme is used, in conjunction with a realistic but schematic Hamiltonian that includes the most important multipole terms, to describe the energy spectra and B(E2) transition strengths of 20-Ne, 22-Ne, 24-Mg and 28-Si. The effect of the size of the Hilbert space on both sets of observables is discussed, as well as the structure of the Yrast band and the importance of the various terms in the Hamiltonian.

Shell model description of normal parity bands in odd-mass heavy deformed nuclei

The shell model is a fundamental theory that is applicable in nuclear, atomic, and nonrelativistic quark physics @1# .I n its simplest formulation it provides a natural explanation of magic numbers as shell closures and the energy spectra of closed shell 61 odd-mass nuclei @2,3#. Powerful computers and special algorithms for diagonalizing large matrices have allowed systematic studies of nuclei of the sd shell @4# and pf shell up to A556 @5#. New methods for solving large scale shell-model problems in medium mass nuclei have also been developed @6#. A shell-model description of heavy nuclei requires further assumptions that include a systematic and proper truncation of the model space @1#. In light deformed nuclei the dominance of the quadrupole-quadrupole interaction led to the introduction of the SU~3! shell model @7#, and with it a very natural means to truncate large model spaces. Although realistic interactions mix different irreducible representations ~irreps!, the ground state wave function of well-deformed light nuclei normally consists of only a few SU~3! irreps @8‐11#. The strong spinorbit interaction renders the usual SU~3! scheme useless in heavy nuclei, but at the same time pseudospin emerges as a good symmetry @12‐14#. Pseudospin symmetry refers to the experimental fact that single-particle orbitals with j5l21/2 and j5(l22)11/2 in the shell h lie very close in energy and can therefore be labeled as pseudospin doublets with quantum numbers j

Interband B ( E 2 ) transition strengths in odd-mass heavy deformed nuclei

Interband

Inter-band B(E2) transitions strengths in 160-170Dy nuclei

B(E2)

Isovectorial pairing in solvable and algebraic models

transition strengths between different normal parity bands in

Shape coexistence in the neutron-deficient Pt isotopes in the configuration-mixed IBM

{}^{163}mathrm{Dy}

Sources for conformally flat stationary cyclic circular space‐time

and

Shell model description of band structure in 48Cr

{}^{165}mathrm{Er}

Excited bands in even‐even rare‐earth nuclei

are described using the pseudo-SU(3) model. The Hamiltonian includes Nilsson single-particle energies, quadrupole-quadrupole and pairing interactions with fixed, parametrized strengths, and three extra rotor terms used to fine tune the energy spectra. In addition to interband transitions, the energy spectra and the ground state intraband B(E2) strengths are reported. The results show the pseudo-SU(3) shell model to be a powerful microscopic theory for a description of the normal parity sector in heavy deformed odd-