Nuclear shape transitions, level density, and underlying interactions

Abstract

The configuration interaction approach to nuclear structure uses the effective Hamiltonian in a finite orbital space. The various parts of this Hamiltonian and their interplay are responsible for specific features of physics including the shape of the mean field and level density. This interrelation is not sufficiently understood. We intend to study phase transitions between spherical and deformed shapes driven by different parts of the nuclear Hamiltonian and to establish the presence of the collective enhancement of the nuclear level density by varying the shell-model matrix elements. Varying the interaction matrix elements we define, for nuclei in the sd and pf shells, the sectors with spherical and deformed shapes. Using the moments method that does not require the full diagonalization we relate the shape transitions with the corresponding level density. Enhancement of the level density in the low-energy part of the spectrum is observed in clear correlation with a deformation phase transition induced mainly by the matrix elements of single-particle transfer. The single-particle transfer matrix elements in the shell model nuclear Hamiltonian are indeed the carriers of deformation, providing rotational observables and enhanced level densities.

10 pages, 6 figures

References in corpus (6)

• Nuclear Level Density: Shell Model vs Mean Field
• A High-Performance Fortran Code to Calculate Spin- and Parity-Dependent Nuclear Level Densities
• Invariant correlational entropy as a signature of quantum phase transitions in nuclei
• Predominance of Prolate Nuclear Deformations Emerging from Many-Body Interactions
• Quantum phase transitional patterns in the SD-pair shell model
• High-Performance Algorithm for Calculating Non-Spurious Spin- and Parity-Dependent Nuclear Level Densities

Cited by in corpus (7)

• From bound states to the continuum
• Quantum phase transitions and collective enhancement of level density in odd-A and odd-odd nuclei
• Level density of the $sd$-nuclei $-$ statistical shell-model predictions
• Level density within a micro-macroscopic approach
• Shell-structure and asymmetry effects in level densities
• Microscopic-macroscopic level densities for low excitation energies
• Nuclear structure properties and weak interaction rates of even-even Fe isotopes