Mass-split dependence of pre-scission neutron multiplicity by four-dimensional Langevin dynamics in 16,18O, 40Ar and 64Ni-induced fusion–fission reactions

2019 ◽  
Vol 28 (09) ◽  
pp. 1950077
Author(s):  
D. Naderi ◽  
S. A. Alavi ◽  
V. Dehghani
Keyword(s):  
Asymmetry Parameter ◽  
Reasonable Agreement ◽  
Neutron Emission ◽  
Level Density ◽  
Neutron Multiplicity ◽  
Density Parameter ◽  
Fission Reactions ◽  
Orientation Degree ◽  
Langevin Model ◽  
Neck Thickness

By using the multidimensional Langevin model, including elongation, neck thickness, asymmetry parameter and orientation degree of freedom, the fission dynamics of some [Formula: see text]O-, [Formula: see text]Ar- and [Formula: see text]Ni-induced fusion–fission reactions were investigated. We calculated mean pre-scission neutron kinetic energy, pre-scission neutron multiplicity and fission time. Mass-split dependence of pre-scission neutron multiplicity and sensitivity of multiplicity on different value of the level density parameter for fission and neutron emission of highly excited compound nuclei were studied. One can conclude reasonable agreement between theory and tentative results for different reactions.

Effects of level density parameter on the superheavy production in cold fusion

2014 ◽  
Vol 29 (40) ◽  
pp. 1450214 ◽  
Author(s):  
M. R. Pahlavani ◽  
S. A. Alavi
Keyword(s):  
Cross Section ◽  
Neutron Emission ◽  
Level Density ◽  
Cold Fusion ◽  
Heavy Ion ◽  
Evaporation Residue ◽  
Density Parameter ◽  
Fusion Reactions ◽  
Level Density Parameter ◽  
Evaporation Residue Cross Section

By using semiclassical method and considering Woods–Saxon and Coulomb potentials, the level density parameter a was calculated for three superheavy nuclei 270110, 278112 and 290116. Obtained results showed that the value of level density parameter of these nuclei is near to the simple relation a ≈ A/10. In framework of the dinuclear system model, the effects of level density parameter on the probability of the formation of a compound nucleus, the ratio of neutron emission width and fission width, and evaporation residue cross-section of three cold fusion reactions 62 Ni +208 Pb , 70 Zn +208 Pb and 82 Se +208 Pb , leading to superheavy elements were investigated. The findings indicate that the level density parameter play a significant role in calculations of heavy-ion fusion–fission reactions. The obtained results in the case of a = A/12 have larger values in comparison with calculated level density parameter with Woods–Saxon potential (a WS ) and a = A/10. The theoretical results of the evaporation residue cross-section are very sensitive to the choice of level density parameter. The calculated values with a WS are in good agreement with experimental values.

Study of fission time and prescission neutron multiplicity using four-dimensional Langevin equations

2014 ◽  
Vol 23 (12) ◽  
pp. 1450087 ◽  
Author(s):  
D. Naderi
Keyword(s):  
Stochastic Dynamics ◽  
Stochastic Approach ◽  
Degree Of Freedom ◽  
Neutron Multiplicity ◽  
Langevin Equations ◽  
Orientation Degree ◽  
Four Dimensions ◽  
Dissipation Coefficient ◽  
Mass Asymmetry ◽  
Neck Thickness

In this paper, four-dimensional stochastic approach is applied on dynamics of fission process to calculate mean fission time and prescission neutron multiplicity. Elongation, neck thickness, mass asymmetry and orientation degree of freedom (K-coordinate) are four dimensions in dynamical calculations. In order to investigate the influence of the dissipation coefficient of K-coordinate, the stochastic dynamics of the orientation degree of freedom using nonconstant dissipation coefficient was studied. Calculations were done for the 16 O +208 Pb and 16 O +232 Th reactions. Obtained results were compared with a constant dissipation coefficient (γK = 0.077( MeVzs )-1/2). The mean fission time and prescission neutron multiplicity for nonconstant dissipation case were lower than for the constant one.

Investigation of level density parameter dependence for some 233U, 235U, 237U, 239U, 249Cf, 251Cf, 237Pu and 247Cm nuclei in neutron fission cross sections with the incident energy up to 20 MeV

Kerntechnik ◽  
2021 ◽  
Vol 86 (1) ◽  
pp. 78-85
Author(s):  
Ö. Sönmez ◽  
O. Karaman
Keyword(s):  
Cross Sections ◽  
Nuclear Reactions ◽  
Level Density ◽  
Medical Application ◽  
Density Parameter ◽  
Fission Reactions ◽  
Neutron Fission ◽  
Level Density Parameter ◽  
Nuclear Data Library ◽  
The Cross

Abstract Level density models have increasing importance to gain more in-depth into the nature of nuclear reactions. Many novel and advanced medical application use radioisotopes, which are produced with nuclear reactions. In this study, the effect of the level density parameters of the nucleus on the cross sections of neutron-fission reactions for 233U, 235U, 237U, 239U, 249Cf, 251Cf, 237Pu and 247Cm nuclei were investigated for up to 20 MeV neutrons. TALYS 1.8 software was used to calculate the cross-sections of neutron-fission reactions for different level density parameters. The calculations were compared with the EXFOR nuclear data library and the level density parameters, and the closest fit were searched. As outputs of the study, the effect of selection of level density parameter on cross section calculations was observed. The theoretically obtained data were compared with the experimental data taken from the literature. The results are presented graphically for better interpretation.

scholarly journals Impact of FIFRELIN input parameters on fission observables

2018 ◽  
Vol 193 ◽  
pp. 01003
Author(s):  
Abdelaziz Chebboubi ◽  
Olivier Litaize ◽  
Olivier Serot
Keyword(s):  
Nuclear Reactor ◽  
Neutron Emission ◽  
Level Density ◽  
Strength Function ◽  
Nuclear Data ◽  
Neutron Multiplicity ◽  
Monte Carlo Code ◽  
Nuclear Level Density ◽  
Fission Fragments ◽  
The Impact

Evaluated nuclear data are essential for nuclear reactor studies. In order to significantly improve the precision of nuclear data, more and more fundamental fission models are used in the evaluation processing. Therefore, tests of fission models become a central issue. In this framework, FIFRELIN (FIssion Fragments Evaporation Leading to an Investigation of Nuclear data) is a Monte Carlo code developed in order to modelize fission fragments de-excitation through the emission of neutrons, γ and conversion e-. To be performed, a FIFRELIN calculation relies on several models such as gamma strength function and nuclear level density and of more empirical hypothesis such as total excitation energy repartition or angular momentum given by the fission reaction. Moreover, pre-emission mass yield and kinetic energy distribution per mass are necessary to process the simulation. A set of five free parameters are chosen to reproduce a target observable. Often this observable corresponds to the mean neutron multiplicity for heavy and light fragment. In this work, the impact of the set of parameters on different output observables (neutron emission probability, neutron multiplicity as function of the fission fragment mass) is investigated.

Pre-saddle and pre-scission neutron emission rates in heavy-ion induced fission of 16O +208Pb and 16O +209Bi systems

2019 ◽  
Vol 28 (03) ◽  
pp. 1950013
Author(s):  
Saeed Soheyli ◽  
Morteza Khalil Khalili ◽  
Ghazaaleh Ashrafi
Keyword(s):  
Emission Rate ◽  
Neutron Emission ◽  
Nonlinear Behavior ◽  
Heavy Ion ◽  
Neutron Multiplicity ◽  
Emission Rates ◽  
Reaction Systems ◽  
Initial Excitation ◽  
Induced Fission ◽  
First Time

Whereas there is a slight information on the pre-saddle neutron emission rate and neutron multiplicity, as well as it is impossible to separate the pre-saddle and saddle to scission neutron contributions experimentally, the theoretical studies of pre-saddle neutron emission rate and neutron multiplicity are of great importance. In the present work, the calculations of pre-saddle neutron multiplicity are performed using the analysis of fission fragment angular anisotropy data for [Formula: see text] and [Formula: see text] reaction systems. The obtained results show that the pre-saddle neutron multiplicity decreases by increasing the initial excitation energy and it has found to be characterized by a nonlinear behavior. Through the analysis of pre-saddle neutron multiplicity and pre-saddle transition time by means of the neutron clock method, the pre-saddle neutron emission rate is calculated for the first time. The findings of this study show that the pre-scission neutron emission rate is lower than the pre-saddle neutron emission rate.

Temperature and isospin dependence of the level-density parameter in the A≈110 mass region

2020 ◽  
Vol 102 (5) ◽  
Author(s):  
G. K. Prajapati ◽  
Y. K. Gupta ◽  
B. V. John ◽  
B. N. Joshi ◽  
Harjeet Kaur ◽  
...  
Keyword(s):  
Level Density ◽  
Mass Region ◽  
Density Parameter ◽  
Level Density Parameter ◽  
Isospin Dependence
Sign in / Sign up

Export Citation Format

Share Document