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Large-scale shell model calculations were performed for neutron-rich even-even $^{132-136}$Te using a realistic effective interaction derived from CD-Bonn nucleon-nucleon potential for the positive and negative parity states. The calculated…

Nuclear Theory · Physics 2007-05-23 F. A. Majeed

We devise a framework based on the generalized contact formalism that combines the nuclear shell model and quantum Monte Carlo methods and compute the neutrinoless double-beta decay of experimentally relevant nuclei, including $^{76}$Ge,…

Nuclear Theory · Physics 2022-12-21 Ronen Weiss , Pablo Soriano , Alessandro Lovato , Jaview Menendez , R. B. Wiringa

It is almost 80 years since Hans Bethe described the level density as a non-interacting gas of protons and neutrons. In all these years, experimental data were interpreted within this picture of a fermionic gas. However, the renewed…

An accurate description of low-density nuclear matter is crucial for explaining the physics of neutron star crusts. In the density range between approximately 0.01 fm$^{-3}$ and 0.1 fm$^{-3}$, matter transitions from neutron-rich nuclei to…

Nuclear Theory · Physics 2024-08-01 Bryce Fore , Jane Kim , Morten Hjorth-Jensen , Alessandro Lovato

The modern form of the Moments Method applied to the calculation of the nuclear shell-model level density is explained and examples of the method at work are given. The calculated level density practically exactly coincides with the result…

Nuclear Theory · Physics 2016-01-27 V. Zelevinsky , M. Horoi , R. A. Sen'kov

Quantum Monte Carlo methods find fruitful application in large shell model problems. These methods reduce the imaginary-time many-body evolution operator to a coherent superposition of one-body evolutions in a fluctuating one-body field;…

Nuclear Theory · Physics 2008-02-03 S. E. Koonin

The level density of quantum states in statistical mesoscopic systems is a critical input for various fields of physics, including nuclear physics, nuclear astrophysics, atomic physics and their applications. In atomic nuclei, the level…

A mean-field plus pairing model for atomic nuclei in the Fe region was studied using a finite-temperature quantum Monte-Carlo method. We present results for thermodynamical quantities such as the internal energy and the specific heat. These…

Nuclear Theory · Physics 2008-11-26 S. Rombouts , K. Heyde , N. Jachowicz

The death of the massive stars due to supernova explosion is a key ingredient in stellar evolution, stellar population synthesis. The electron capture (EC) plays a vital role in supernovae explosions. According to the Shell-Model Monte…

Nuclear Theory · Physics 2017-07-18 Jing-Jing Liu , Qiu-He Peng , Dong-Mei Liu

Accurate knowledge of the nuclear level density is important both from a theoretical viewpoint as a powerful instrument for studying nuclear structure and for numerous applications. For example, astrophysical reactions responsible for the…

Nuclear Theory · Physics 2017-10-10 S. Karampagia , R. A. Senkov , V. Zelevinsky

Based on large-scale shell model calculations we have determined the electron capture, positron capture and beta-decay rates on more than 100 nuclei in the mass range A=45-65. The rates are given for densities \rho Y_e =10^7-10^{10}…

Nuclear Theory · Physics 2011-05-05 K. Langanke , G. Martinez-Pinedo

We investigate the nature and impact of shell effects on nuclear level density (NLD) and particle emission probability as a function of temperature in a microscopic theoretical framework of Statistical Model for nuclei ranging from neutron…

Nuclear Theory · Physics 2023-03-03 Mamta Aggarwal

We report on the development of a new shell-model Monte Carlo algorithm which uses the proton-neutron formalism. Shell model Monte Carlo methods, within the isospin formulation, have been successfully used in large-scale shell-model…

Nuclear Theory · Physics 2015-06-26 C. Ozen , D. J. Dean

Starting from an independent-particle model with a finite and arbitrary set of single-particle energies, we develop an analytical approximation to the many-body level density $\rho_A(E)$ and to particle-hole densities. We use exact…

Nuclear Theory · Physics 2013-09-30 Adriana Pálffy , Hans A. Weidenmüller

The nuclear level densities and level-density parameters in fissioning nuclei at their saddle points of fission barriers - $a_{f}$, as well as those for neutron - $a_{n}$, proton - $a_{p}$ , and $\alpha$-particle - $a_{\alpha}$ emission…

Nuclear Theory · Physics 2021-08-31 A. Rahmatinejad , T. M. Shneidman , G. Adamian , N. V. Antonenko , P. Jachimowicz , M. Kowal

A generalized method to calculate the excitation-energy dependent parity ratio in the nuclear level density is presented, using the assumption of Poisson distributed independent quasi particles combined with BCS occupation numbers. It is…

A new method to calculate level densities for non-interacting Fermions within the constant-spacing model with a finite number of states is developed. We show that asymptotically (for large numbers of particles or holes) the densities have…

Nuclear Theory · Physics 2013-01-08 Adriana Pálffy , Hans A. Weidenmüller

We utilize the Shell Model Monte Carlo (SMMC) method to study the structure of rare earth nuclei. This work demonstrates the first systematic ``full oscillator shell plus intruder'' calculations in such heavy nuclei. Exact solutions of a…

Nuclear Theory · Physics 2009-10-31 J. A. White , S. E. Koonin , D. J. Dean

Statistical level density $\rho(E,A)$ is derived for nucleonic system with a given energy $E$, particle number $A$ and other integrals of motion in the micro-macroscopic approximation beyond the standard saddle-point method of the Fermi gas…

Nuclear Theory · Physics 2022-03-08 A. G. Magner , A. I. Sanzhur , S. N. Fedotkin , A. I. Levon , S. Shlomo

The shell-model Monte Carlo (SMMC) technique transforms the traditional nuclear shell-model problem into a path-integral over auxiliary fields. We describe below the method and its applications to four physics issues: calculations of sdpf-…

Nuclear Theory · Physics 2009-10-31 D. J. Dean , J. A. White