scholarly journals Level studies of 73As via 73Ge(p, nγ)73As reaction and density of discrete levels in 73As

2009 ◽  
Vol 24 (2) ◽  
pp. 82-85 ◽  
Author(s):  
Aziz Behkami ◽  
Rohallah Razavi ◽  
Tayeb Kakavand
Keyword(s):  
Proton Beam ◽  
Excited States ◽  
Level Scheme ◽  
Level Density ◽  
Fermi Gas ◽  
Temperature Model ◽  
Nuclear Level Density ◽  
Nuclear Level ◽  
Level Densities ◽  
Experimental Level

The excited states of 73As have been investigated via the 73Ge(p, n?)73As reaction with the proton beam energies from 2.5-4.3 MeV. The parameters of the nuclear level density formula have been determined from the extensive and complete level scheme for 73As. The Bethe formula for the back-shifted Fermi gas model and the constant temperature model are compared with the experimental level densities.

scholarly journals Level studies of 93Mo via 93Nb(p, nγ)93Mo reaction and density of discrete levels in 93Mo

2011 ◽  
Vol 26 (1) ◽  
pp. 69-73 ◽  
Author(s):  
Rohallah Razavi ◽  
Tayeb Kakavand
Keyword(s):  
Proton Beam ◽  
Excited States ◽  
Level Scheme ◽  
Level Density ◽  
Fermi Gas ◽  
Temperature Model ◽  
Nuclear Level Density ◽  
Nuclear Level ◽  
Level Densities ◽  
Experimental Level

The excited states of 93Mo have been investigated via the 93Nb(P,n?)93Mo reaction with proton beam energies of 2.5-4.3 MeV. The parameters of the nuclear level density formula were determined from the extensive and complete level scheme of 93Mo. The Bethe formula for the back-shifted Fermi gas model and the constant temperature model are compared with experimental level densities.

A COMPOSITE NUCLEAR-LEVEL DENSITY FORMULA WITH SHELL CORRECTIONS

1965 ◽  
Vol 43 (8) ◽  
pp. 1446-1496 ◽  
Author(s):  
A. Gilbert ◽  
A. G. W. Cameron
Keyword(s):  
Lower Energy ◽  
Level Density ◽  
Energy Levels ◽  
Fermi Gas ◽  
Experimental Information ◽  
Shell Correction ◽  
Nuclear Level Density ◽  
Excitation Energies ◽  
Nuclear Level ◽  
Level Densities

At low excitation energies a "constant nuclear temperature" representation of nuclear-level densities is used, and at high excitation energies the regular Fermi gas formula is adopted. A method is developed for determining the parameters of the Fermi gas formula by using both the pairing and the shell-correction energies found by Cameron and Elkin for their semiempirical atomic mass formula in its exponential form. This procedure determines level densities at neutron-binding-energy excitations subject to an average factor error of 1.8. Methods are also developed for determining the parameters for the lower-energy formula in such a way that it best fits the lower-energy levels and joins smoothly to the Fermi gas formula. Correlations of the resulting parameters with shell and pairing effects are found. A composite prescription is given for calculating level densities in nuclei for which no experimental information is known. Tables give level density parameters for a wide variety of nuclei for which some experimental information is known. Some of the derivations of the Fermi gas formula in the literature were found to be slightly incorrect, so new derivations are presented in Appendixes.

scholarly journals Updated nuclear level density parameters of 153Sm nucleus within the back-shifted Fermi gas model

2021 ◽  
Vol 63 (1) ◽  
pp. 6-10
Author(s):  
Ngoc Anh Nguyen ◽  
◽  
Xuan Hai Nguyen ◽  
Quang Hung Nguyen ◽  
Tan Phuc Le ◽  
...  
Keyword(s):  
Level Scheme ◽  
Level Density ◽  
Energy Parameter ◽  
Nuclear Research ◽  
Fermi Gas ◽  
Reference Database ◽  
Density Parameter ◽  
Nuclear Level Density ◽  
Nuclear Level ◽  
Level Density Parameter

The present work re-evaluates the level density parameter a, asymptotic level density parameter aasy, and back-shifted energy parameter E1 within the back-shifted Fermi gas model (BSFG) for the 153Sm nucleus. This reevaluation is based on the experimental nuclear level scheme extracted from the ENSDF library, the average level spacing at the neutron binding energy (D0 value), and the latest updated nuclear level scheme obtained from an experimental gamma cascade experiment, which was performed at the Dalat Nuclear Research Reactor using the thermal neutron beam. The updated values of the BSFG level parameters are: (1) a=18.09±0.25 MeV-1and E1=-0.92±0.07 MeV for the energy-independent level density parameter; and (2) aasy=15.00±0.20 MeV-1and E1=-0.81±0.08 MeV for the energy-dependent level density parameter. It has been found that the total nuclear level densities calculated using these updated parameters agree with the experimental data better than those using parameters taken from the nuclear reference database RIPL-3. These updated parameters are more accurate and reliable than those extracted from RIPL-3 and are, therefore, highly recommended for all the applications hereafter.

Studying Nuclear Level Densities of 238U in the Nuclear Reactions within the Macroscopic Nuclear Models

2016 ◽  
Vol 71 (2) ◽  
pp. 157-160
Author(s):  
Rohallah Razavi ◽  
Azam Rahmatinejad ◽  
Tayeb Kakavand ◽  
Fariba Taheri ◽  
Maghsood Aghajani ◽  
...  
Keyword(s):  
Constant Temperature ◽  
Nuclear Reactions ◽  
Level Density ◽  
Recent Experimental Data ◽  
Nuclear Level Density ◽  
Nuclear Level ◽  
Excitation Functions ◽  
Level Densities ◽  
Nuclear Models ◽  
Experimental Values

AbstractIn this work the nuclear level density parameters of 238U have been extracted in the back-shifted Fermi gas model (BSFGM), as well as the constant temperature model (CTM), through fitting with the recent experimental data on nuclear level densities measured by the Oslo group. The excitation functions for 238U(p,2nα)233Pa, and 238U(p,4n)235Np reactions and the fragment yields for the fragments of the 238U(p,f) reaction have been calculated using obtained level density parameters. The results are compared to their corresponding experimental values. It was found that the extracted excitation functions and the fragment yields in the CTM coincide well with the experimental values in the low-energy region. This finding is according to the claim made by the Oslo group that the extracted level densities of 238U show a constant temperature behaviour.

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.

Back shifted Fermi gas model with temperature dependent pairing energy: Thermal properties of 98Mo

2016 ◽  
Vol 25 (09) ◽  
pp. 1650065
Author(s):  
S. A. Alavi ◽  
V. Dehghani
Keyword(s):  
Experimental Data ◽  
Heat Capacity ◽  
Level Density ◽  
Fermi Gas ◽  
Nuclear Level Density ◽  
Temperature Dependent ◽  
Nuclear Level ◽  
Ginzburg Landau ◽  
The Mean ◽  
Good Agreement

The effect of using a temperature dependent pairing term in back-shifted Fermi-gas (BSFG) formula of nuclear level density has been studied. We have used the mean order parameter formula of modified Ginzburg–Landau (MGL) theory as a simple possible choice for temperature dependency of the pairing term. The level density and heat capacity of [Formula: see text]Mo have been calculated with this formalism and compared with the experimental data. We observed good agreement between the heat capacity of this model and the experimental data.

NUCLEAR LEVEL DENSITY AT FINITE TEMPERATURES

2006 ◽  
Vol 15 (02) ◽  
pp. 478-483 ◽  
Author(s):  
J. BARTEL ◽  
K. POMORSKI ◽  
B. NERLO-POMORSKA
Keyword(s):  
Single Particle ◽  
Level Density ◽  
Mean Field ◽  
Skyrme Force ◽  
Nuclear Level Density ◽  
Nuclear Level ◽  
Level Densities ◽  
Relativistic Mean Field ◽  
Single Particle Level ◽  
Particle Level

Selfconsistent mean-field calculations have been performed with the SkM* Skyrme force for 140 spherical even-even nuclei at temperatures 0≤T≤4 MeV . Single-particle level densities for this sample of nuclei are determined for various temperatures. The average dependence of the single-particle level density on mass number A and isospin is given and compared with previous estimates obtained using the relativistic mean-field and different semiclassical approaches.

NUCLEAR LEVEL DENSITIES CORRECTED FOR FINITE SIZE EFFECTS

1992 ◽  
Vol 07 (17) ◽  
pp. 1503-1507 ◽  
Author(s):  
G.D. YEN ◽  
H.G. MILLER
Keyword(s):  
Density Of States ◽  
Size Effects ◽  
Particle Density ◽  
Level Density ◽  
Finite Size ◽  
Nuclear Level Density ◽  
Nuclear Level ◽  
Finite Size Effects ◽  
Level Densities ◽  
Single Particle Density

Finite size corrections in the calculation of nuclear level densities are considered within the framework of a Fermi gas model. A simple geometrical correction to the single particle density of states leads to an increase in the Fermi energy which drastically reduces the many body density of states. For light nuclei such as 24Mg, the nuclear level density at T≡3 MeVis reduced by roughly an order of magnitude when finite size effects are taken into account and the reduction is more pronounced in heavier systems such as 208Pb.

scholarly journals First results in the study of level scheme for ¹⁷²Yb based on gamma-gamma coincidence spectrometer

2016 ◽  
Vol 6 (4) ◽  
pp. 26-31
Author(s):  
Ngoc Anh Nguyen ◽  
Xuan Hai Nguyen ◽  
Dinh Khang Pham ◽  
Huu Thang Ho
Keyword(s):  
Level Scheme ◽  
Level Density ◽  
Strength Function ◽  
Nuclear Research ◽  
Nuclear Level Density ◽  
Nuclear Level ◽  
Nuclear Research Institute ◽  
Gamma Coincidence ◽  
First Results ◽  
Coincidence Spectrometer

Nuclear level scheme permits to determine nuclear level density, gamma strength function, and to evaluate nuclear models. In comparison to light nuclei, the structure of heavy nuclei is much more complicated because of their strong deformation. In order to study nuclear level scheme, gamma – gamma coincidence spectrometer with advantages of low Compton background and the ability of identifying correlated gamma transitionshas been often used. This paper presents the first results of an experimentalstudy of level scheme of 172Yb using gamma – gamma coincidence spectrometer at the Dalat Nuclear Research Institute.

Sign in / Sign up

Export Citation Format

Share Document