scholarly journals Shell model calculations in the A ~ 100 mass region

2020 ◽  
Vol 6 ◽  
pp. 225
Author(s):  
P. Divari ◽  
L. D. Skouras
Keyword(s):  
Shell Model ◽  
Large Scale ◽  
Model Space ◽  
Mass Region ◽  
Matrix Elements ◽  
Model Calculations ◽  
Single Neutron ◽  
Least Squares Fit ◽  
The Matrix ◽  
Inert Core

The properties of nuclei with 39≤Ζ≤47 and Ν=51-52 are investigated in large scale shell-model calculations. The doubly closed nucleus 100Sn is selected as the reference state and the nuclei under examination are described in terms of proton holes and one up two neutrons outside the inert core. The proton holes are distributed in a model space consisting of the orbitals g9/2, p1/2, p3/2 while f5/2 is sometimes also considerd. Similary the model space for the neutron particles in­ cludes the orbitals g7/2, d5/2, d3/2, s1/2 and in certain cases h11/2. The effective two-body interaction and the matrix elements of the effective operators were deter­ mined by introducing second-order corrections to the Sussex matrix elements. The single proton holes as well as the single-neutron energies were treated as parameters which were determined by least-squares fit to the observed levels of 39≤Ζ≤47, Ν=50 and Ν=51 respectively. The results of the calculation were found to be in satisfactory agreement with experimental data and this enable us to make predictions about the properties of some exotic nuclei in the vicinity of 100Sn.

scholarly journals Shell model calculations in the A=90-98 mass region. A study of the N=51. nuclei

2020 ◽  
Vol 5 ◽  
pp. 90
Author(s):  
P. Divari ◽  
L. D. Skouras
Keyword(s):  
Shell Model ◽  
Large Scale ◽  
Model Space ◽  
Mass Region ◽  
Matrix Elements ◽  
Model Calculations ◽  
Single Neutron ◽  
Least Squares Fit ◽  
The Matrix ◽  
Inert Core

The properties of nuclei with 39 < Ζ < 47 and N=51 are investigated in large scale shell-model calculations. The doubly closed nucleus 100Sn is selected as the reference state and the nuclei under examination are described in terms of proton holes and a single neutron outside the inert core. The proton holes are distributed in a model space consisting of the orbitals g9/2, p1/2, p3/2 while f5/2 is sometimes also considerd. Similary the model space for the single neutron includes the orbitals g7/2, d5/2, d3/2, s1/2 and in certain cases h11/2. The effective two-body interaction and the matrix elements of the effective operators were determined by introducing second-order correctios to the Sussex matrix elements. The single proton holes as well as the single-neutron energies were treated as parameters which were determined by least-squares fit to the observed levels of 39 < Ζ < 47, N=50 and Ν=51 respectively. The results of the calculation were found to be in satisfactory agreement with experimental data and this enable us to make predictions about the properties of some exotic nuclei in the vicinity of 100Sn.

scholarly journals Large Scale Shell Model Calculations of the Negative-Parity States Structure in 24Mg Nucleus

2021 ◽  
Vol 66 (4) ◽  
pp. 293
Author(s):  
A.A. Al-Sammarraie ◽  
F.A. Ahmed ◽  
A.A. Okhunov
Keyword(s):  
Shell Model ◽  
Large Scale ◽  
Transition Probabilities ◽  
Transition Probability ◽  
Energy Levels ◽  
Form Factors ◽  
Model Space ◽  
Negative Parity ◽  
Matrix Elements ◽  
Model Calculations

The negative-parity states of 24Mg nucleus are investigated within the shell model. We are based on the calculations of energy levels, total squared form factors, and transition probability using the p-sd-pf (PSDPF) Hamiltonian in a large model space (0 + 1) hW. The comparison between the experimental and theoretical states showed a good agreement within a truncated model space. The PSDPF-based calculations successfully reproduced the data on the total squared form factors and transition probabilities of the negative-parity states in 24Mg nucleus. These quantities depend on the one-body density matrix elements that are obtained from the PSDPF Hamiltonian. The wave functions of radial one-particle matrix elements calculated with the harmonic-oscillator potential are suitable to predict experimental data by changing the center-of-mass corrections.

scholarly journals Shell model calculations in the A=80-100 mass region and study of double β transitions

2020 ◽  
Vol 1 ◽  
pp. 156
Author(s):  
J. Sinatkas ◽  
L. D. Skouras ◽  
D. Strottman ◽  
J. D. Vergados
Keyword(s):  
Shell Model ◽  
Satisfactory Agreement ◽  
Effective Interaction ◽  
Model Space ◽  
Mass Region ◽  
Least Square ◽  
Matrix Elements ◽  
Model Calculations ◽  
Least Square Fit ◽  
The One

The structure of the Ζ,Ν < 50 nuclei is examined in a model space consisting of the 0g9/2, 1p1/2, 1p3/2 and the 0f5/2 hole orbitals outside the doubly closed 100Sn core. The effective interaction for this model space is derived by introducing second order corrections to the Sussex matrix elements, while the one-hole energies are deduced by a least square fit to the observed levels. The results of the calculation are found to be in very satisfactory agreement with experiment for all nuclei with 38<Ζ<46 but for Ζ<38 this agreement begins to deteriorate. Such a feature possibly indicates the appearance of deformation and the breaking of the Ν=50 core. The wavefunctions of the calculation are used to determine double β matrix elements in the Ge, Se, Sr and Kr isotopes.

scholarly journals Double beta decay without invoking closure

2020 ◽  
Vol 1 ◽  
pp. 45
Author(s):  
G. Pantis ◽  
J. D. Vergados
Keyword(s):  
Shell Model ◽  
Beta Decay ◽  
Nuclear Matrix ◽  
Model Space ◽  
Double Beta Decay ◽  
Matrix Elements ◽  
Model Calculations ◽  
Closure Approximation ◽  
The Matrix

The nuclear matrix elements of PU operators entering in the 0v ßß-decay of 76Ge-->76Se have been calculated explicitly  in the context of QRPA within the model space 0f7/2 - 0h11/2. T h e validity of the closure approximation has been tested and seems to be quite satisfactory for those matrix elements which are not usually suppressed. Our results indicate that they are dominated by multipoles other than 0+ and 1+ and that the matrix elements are comparable to those of shell model calculations.

scholarly journals ββ DECAY AND NUCLEAR STRUCTURE

2007 ◽  
Vol 16 (02) ◽  
pp. 552-560 ◽  
Author(s):  
E. CAURIER ◽  
F. NOWACKI ◽  
A. POVES
Keyword(s):  
Shell Model ◽  
Nuclear Matrix ◽  
Large Scale ◽  
Predictive Power ◽  
Strong Impact ◽  
Matrix Elements ◽  
Model Calculations ◽  
Mode Stability ◽  
Recent Developments

The determination of accurate nuclear matrix elements for ββ decay processes is a challenge for nuclear theory and can have a strong impact in neutrino physics. Large Scale Shell Model (LSSM) calculations are among the best tools for such determination and recent developments have allowed to extend its application domains. In particular, systematic studies of nuclear matrix elements calculations have been now undertaken in this framework for most of the ββ emitters. These calculations are crucial in the determination of the most favorable emitters in the forthcoming generation of ββ experiments. The present paper focuses on the recent advances and remaining difficulties of shell model calculations for the neutrinoless mode. Stability and predictive power of the results will be discussed.

scholarly journals Shell Model Calculations for Some Properties of 29-34Mg Isotopes

2021 ◽  
pp. 1901-1911
Author(s):  
Lubna Abduljabbar Mahmood ◽  
Ghaith Naima Flaiyh
Keyword(s):  
Shell Model ◽  
Transition Probability ◽  
Effective Interaction ◽  
Model Space ◽  
High Energy ◽  
Neutron Separation Energy ◽  
Separation Energy ◽  
Model Calculations ◽  
Model Code ◽  
Single Neutron

The calculations of the shell model, based on the large basis, were carried out for studying the nuclear 29-34Mg structure. Binding energy, single neutron separation energy, neutron shell gap, two neutron separation energy, and reduced transition probability, are explained with the consideration of the contributions of the high-energy configurations beyond the model space of sd-shell. The wave functions for these nuclei are used from the model of the shell with the use of the USDA 2-body effective interaction. The OBDM elements are computed with the use of NuShellX@MSU shell model code that utilizes the formalism of proton-neutron.

scholarly journals Investigation of the level structure of 90Nb nucleus using the shell model

Nukleonika ◽  
2019 ◽  
Vol 64 (4) ◽  
pp. 113-116
Author(s):  
Wu Yi-Heng ◽  
Yang Dong ◽  
Ma Ke-Yan ◽  
Luo Peng-Wei
Keyword(s):  
Shell Model ◽  
Level Structure ◽  
Model Space ◽  
Negative Parity ◽  
Spin States ◽  
Shell Closure ◽  
Model Calculations ◽  
High Spin States ◽  
Single Neutron ◽  
Subshell Closure

Abstract Shell model calculations have been carried out for 90Nb nucleus with the model space in which the valence protons occupy the f5/2, p3/2, p1/2, and g9/2 orbitals and the valence neutrons occupy the p1/2, g9/2, d5/2, and g7/2 orbitals. According to the calculated results, the negative parity is from the contribution of the proton of the f5/2, p3/2, and p1/2 orbits. The moderate spin states of 90Nb are mainly due to the excitation of protons from the f5/2 and p3/2 orbits to the p1/2 and g9/2 orbits across the Z = 38 subshell closure, and the high spin states arise from the excitation of a single neutron from the g9/2 orbit into the d5/2 orbit across the N = 50 shell closure.

scholarly journals Study of nuclei around Z = 28 by large-scale shell model calculations

2013 ◽  
Vol 445 ◽  
pp. 012028 ◽  
Author(s):  
Y Tsunoda ◽  
T Otsuka ◽  
N Shimizu ◽  
M Honma ◽  
Y Utsuno
Keyword(s):  
Shell Model ◽  
Large Scale ◽  
Model Calculations
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