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We introduce a novel method to obtain level densities in large-scale shell-model calculations. Our method is a stochastic estimation of eigenvalue count based on a shifted Krylov-subspace method, which enables us to obtain level densities…

We use quantum Monte Carlo methods in the framework of the interacting nuclear shell model to calculate the statistical properties of nuclei at finite temperature and/or excitation energies. With this approach we can carry out realistic…

Nuclear Theory · Physics 2009-11-11 Y. Alhassid

It is shown that nuclear level densities in a finite space are described by a continuous binomial function, determined by the first three moments of the Hamiltonian, and the dimensionality of the underlying vector space. Experimental values…

Nuclear Theory · Physics 2009-10-31 A. P. Zuker

The prediction of cross sections for nuclei far off stability is crucial in the field of nuclear astrophysics. We discuss the model mostly employed for such calculations: the statistical model (Hauser-Feshbach). Special emphasis is put on…

Astrophysics · Physics 2008-11-26 T. Rauscher , F. -K. Thielemann , K. -L. Kratz

A microscopic method for calculating nuclear level densities (NLD) is developed, based on the framework of energy density functionals. Intrinsic level densities are computed from single-quasiparticle spectra obtained in a finite-temperature…

Nuclear Theory · Physics 2020-11-18 Jie Zhao , Tamara Nikšić , Dario Vretenar

A new algorithm for calculating the spin- and parity-dependent shell model nuclear level densities using the moments method in the proton-neutron formalism is presented. A new, parallelized code based on this algorithm was developed and…

Nuclear Theory · Physics 2014-11-20 R. A. Sen'kov , M. Horoi

Because of the rotational invariance of the nuclear Hamiltonian, there exists a density functional for nuclei that depends only on two scalar densities. Practical calculations boil down to radial, one-dimensional ones.

Nuclear Theory · Physics 2008-11-26 B. G. Giraud

The spin and parity dependent nuclear level densities (NLD) are calculated for medium-heavy nuclei using shell model techniques. The NLD are used to calculate cross sections and reaction rates of interest for nuclear astrophysics and…

Nuclear Theory · Physics 2018-01-17 Mihai Horoi , Jayani Dissanayake

We present some results and remarks based on a combinatorial approach of the evaluation of the nuclear level density. First, we show that it is possible to extract some reliable information from the output of the program whose rough data…

Nuclear Theory · Physics 2007-05-23 Bernard PICHON CNRS

A particle-number reprojection method is applied in the framework of the shell model Monte Carlo approach to calculate level densities for a family of nuclei using Monte Carlo sampling for a single nucleus. In particular we can also…

Nuclear Theory · Physics 2009-11-06 S. Liu , Y. Alhassid , H. Nakada

Level density $\rho$ is derived for a finite system with strongly interacting nucleons at a given energy E, neutron N and proton Z particle numbers, projection of the angular momentum M, and other integrals of motion, within the…

Nuclear Theory · Physics 2023-08-22 A. G. Magner , A. I. Sanzhur , S. N. Fedotkin , A. I. Levon , U. V. Grygoriev , S. Shlomo

Realistic nuclear level densities (NLDs) obtained within the spectral distribution method (SDM) are employed to study nuclear processes of astrophysical interest. The merit of SDM lies in the fact that the NLDs corresponding to many body…

Nuclear Theory · Physics 2022-05-04 Sangeeta , T. Ghosh , B. Maheshwari , G. Saxena , B. K. Agrawal

New developments have been brought to our energy-, spin- and parity-dependent nuclear level densities based on the microscopic combinatorial method. Our new calculation is based on the BSkG3 mean-field model which relies on a…

Nuclear Theory · Physics 2026-01-08 S. Goriely , W. Ryssens , S. Hilaire , A. J. Koning

A method to describe spectra starting from nuclear density functionals is explored. The idea is based on postulating an effective Hamiltonian that reproduces the stiffness associated with collective modes. The method defines a simple form…

Nuclear Theory · Physics 2022-08-10 J. Ljungberg , B. G. Carlsson , J. Rotureau , A. Idini , I. Ragnarsson

A high-performance Fortran code is developed to calculate the spin- and parity-dependent shell model nuclear level densities.The algorithm is based on the extension of methods of statistical spectroscopy and implies exact calculation of the…

Nuclear Theory · Physics 2015-06-05 R. Sen'kov , M. Horoi , V. G. Zelevinsky

We have developed an efficient isospin projection method in the shell model Monte Carlo approach for isospin-conserving Hamiltonians. For isoscalar observables this projection method has the advantage of being exact sample by sample. The…

Nuclear Theory · Physics 2008-12-18 H. Nakada , Y. Alhassid

Muonic atom transitions have been measured for almost all stable nuclei to extract nuclear structure properties, including nuclear charge radii and quadrupole moment. To investigate the possibilities of extracting higher-order radial…

Nuclear Theory · Physics 2024-03-20 Hui Hui Xie , Jian Li , Haozhao Liang

Recently we proposed a formalism, based in nuclear statistical spectroscopy, for efficient computation of nuclear level density, or densities of states, through a sum of partitioned binomial functions (SUPARB). In this Letter we extend the…

Nuclear Theory · Physics 2007-05-23 Calvin W. Johnson , Jameel-Un Nabi , W. Erich Ormand

A microscopic method for calculating nuclear level density (NLD) based on the covariant density functional theory (CDFT) is developed. The particle-hole state density is calculated by combinatorial method using the single-particle levels…

Nuclear Theory · Physics 2023-09-27 Kun-Peng Geng , Peng-Xiang Du , Jian Li , Dong-Liang Fang

Actinides are of great interest in astrophysics and technology applications since they can fission. However, the microscopic calculation of their statistical properties in the presence of correlations poses a major theoretical challenge.…

Nuclear Theory · Physics 2026-02-13 D. DeMartini , Y. Alhassid