scholarly journals Moments Method for Shell-Model Level Density

2016 ◽  
Vol 665 ◽  
pp. 012048 ◽  
Author(s):  
V Zelevinsky ◽  
M Horoi ◽  
R A Sen'kov
Keyword(s):  
Shell Model ◽  
Level Density ◽  
Moments Method

Nuclear shell model and level density

2020 ◽  
Vol 29 (06) ◽  
pp. 2030005
Author(s):  
S. Karampagia ◽  
V. Zelevinsky
Keyword(s):  
Shell Model ◽  
Level Density ◽  
Interaction Matrix ◽  
Model Description ◽  
Hamiltonian Matrix ◽  
Matrix Elements ◽  
Nuclear Level Density ◽  
Nuclear Level ◽  
Level Densities ◽  
Moments Method

The accurate knowledge of the nuclear level density is crucial for understanding the nuclear structure and for numerous applications including astrophysical reactions. In this review paper, we discuss the shell-model description of the nuclear level density, the use of the statistical moments method and underlying physics. The level density found with the moments method is shown to agree with the results of the exact diagonalization of the Hamiltonian matrix. The statistical approach is also compared to other standard methods for deriving level densities. The role of specific interaction matrix elements is reviewed in connection to the behavior of the level densities as these evolve. Chaotization and thermalization processes, collective enhancement and phase transitions are discussed with changing strengths of specific groups of two-body interaction matrix elements. The popular phenomenological constant temperature model is compared to the moments method and the effective temperature parameter of the model for different isotopes is discussed.

"Universality" of Gaussian orthogonal ensemble fluctuations: the two-body random ensemble and shell model spectra

1990 ◽  
Vol 68 (3) ◽  
pp. 301-312 ◽  
Author(s):  
Gaetan J. H. Laberge ◽  
Rizwan U. Haq
Keyword(s):  
Energy Level ◽  
Shell Model ◽  
Detailed Analysis ◽  
Close Agreement ◽  
Level Density ◽  
Nuclear Interactions ◽  
Gaussian Orthogonal Ensemble ◽  
Random Hamiltonians

Starting from an appropriate decomposition of the level density into an average and fluctuating part, we studied the energy level fluctuations of an ensemble defined by two-body random Hamiltonians. A detailed analysis of several spectrally averaged fluctuation measures shows close agreement with the predictions of the Gaussian orthogonal ensemble (GOE). This confirms earlier indications that, except for noninteracting particles, fluctuation measures are insensitive to the rank of the interaction. Further, analysis of spectra obtained from realistic nuclear interactions agrees well with the GOE indicating that specific properties of the Hamiltonian have little or no influence on fluctuations. These results, therefore, strengthen our belief in the "universality" of GOE fluctuations.

scholarly journals Stochastic estimation of level density in nuclear shell-model calculations

2016 ◽  
Vol 122 ◽  
pp. 02003 ◽  
Author(s):  
Noritaka Shimizu ◽  
Yutaka Utsuno ◽  
Yasunori Futamura ◽  
Tetsuya Sakurai ◽  
Takahiro Mizusaki ◽  
...  
Keyword(s):  
Shell Model ◽  
Level Density ◽  
Stochastic Estimation ◽  
Nuclear Shell Model ◽  
Model Calculations ◽  
Nuclear Shell
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