scholarly journals Enhanced Fission Probability of Even-Z Fragments in the Decay of Hot and Rotating 210Rn* Compound System

2021 ◽  
Vol 9 (1) ◽  
pp. 43-46
Author(s):  
Dalip Singh Verma ◽  
Kushmakshi .
Keyword(s):  
Isotopic Composition ◽  
Cross Section ◽  
Incident Energy ◽  
Mass Region ◽  
Cluster Decay ◽  
Compound System ◽  
Shell Closure ◽  
Fission Fragments ◽  
Fission Probability ◽  
Fragmentation Potential

Mass and charge distribution of the cross-section for the fission fragments obtained in the decay of hot and rotating compound system formed in the reaction 48Ca + 162Dy → 210Rn* at an incident energy 139.6 MeV has been calculated using the dynamical cluster-decay model. Isotopic composition for each element belonging to the symmetric mass region has been obtained. The shell closure at N=50 for light and at Z=50 for heavy mass binary fragments gives a deep minima in the fragmentation potential at touching configuration and governs the fission partition of the compound system. The fission fragments of the symmetric mass region have their dominating presence along with strong odd-even staggering i.e., even-Z fission fragments are more probable than the odd ones, similar to the observed trends of the yield.

Investigation of the 16O+194Pt reaction: One- and two-dimensional dynamical interpretation

2017 ◽  
Vol 26 (04) ◽  
pp. 1750013 ◽  
Author(s):  
D. Naderi ◽  
A. Farmani
Keyword(s):  
Angular Distribution ◽  
Transition State ◽  
Cross Section ◽  
Fission Cross Section ◽  
Degree Of Freedom ◽  
Two Dimensional ◽  
Orientation Degree ◽  
Fission Fragments ◽  
Fission Probability ◽  
The One

In this paper, we applied the Langevin dynamical model to investigate the different aspects of the [Formula: see text]O+[Formula: see text]Pt reaction. Elongation and orientation degree of freedom ([Formula: see text] coordinate) which are the first and second dimensions of dynamical calculations, are presented here. Fission time, fission cross-section, pre-scission neutron multiplicity, and fission probability were calculated using one- and two-dimensional Langevin equations. Also, anisotropy of fission-fragments angular distribution has been investigated based on the transition state model, one- and two-dimensional Langevin dynamical models. It was found that by adding the orientation degree of freedom to calculations, the fission time and pre-scission neutrons multiplicity increases whereas fission cross-section, and fission probability decreases. The two-dimensional dynamical calculations are a better match to the experimental data than the one-dimensional dynamical calculations, when using nominal values for the reduced dissipation coefficient and shape-dependent level density parameter. However, if model parameters are adjusted to reproduce the fission cross-section data, then both the one- and two-dimensional models give a satisfactory match to the fission fragment anisotropy data. Nonequilibrium [Formula: see text] distributions in the dynamical model can better explain the experimental anisotropy of the angular distribution of fission-fragments with respect to the equilibrium [Formula: see text] distribution in saddle and scission point transition state models.

scholarly journals Effect of Oriented Nuclei on the Competing Modes of α and One-Proton Radioactivities in the Vicinity of Z = 82 Shell Closure

2021 ◽  
Vol 9 (1) ◽  
pp. 31-35
Author(s):  
Sarbjeet Kaur ◽  
BirBikram Singh ◽  
S. K. Patra
Keyword(s):  
Experimental Data ◽  
Cluster Decay ◽  
Proton Emission ◽  
Shell Closure ◽  
Α Decay ◽  
Tunneling Mechanism ◽  
Proton Radioactivity ◽  
Fragmentation Potential ◽  
The One ◽  
Closure Effect

The purpose of the present work is to investigate the alpha (α) emission as competing mode of one proton emission using the preformed cluster decay model (PCM). PCM is based on the quantummechanical tunneling mechanism of penetration of the preformed fragments through a potential barrier, calculated within WKB approximation. To explore the competing aspects of α and one proton radioactivity, we have chosen emitters present immediately above and below the Z = 82 shell closure i.e. 177Tl and 185Bi by taking into account the effects of deformations (β2) and orientations of outgoing nuclei. The minimized values of fragmentation potential and maximized values of preformation probability (P0) for proton and alpha fragment demonstrated the crucial role played by even Z - even N daughter and shell closure effect of Z = 82 daughter, in 177Tl and 185Bi, respectively. The higher values of P0 of the one proton further reveal significance of nuclear structure in the proton radioactivity. From the comparison of proton and α decay, we see that the former is heavily dominating with larger values of P0 in comparison to the later. Theoretically calculated half-lives of one proton and α emission for spherical and deformed considerations have also been compared with available experimental data.

Analysis of n-evaporation from light mass nuclei formed via p-induced reactions

2020 ◽  
Vol 35 (11) ◽  
pp. 2050082
Author(s):  
Amandeep Kaur ◽  
Manoj K. Sharma
Keyword(s):  
Proton Beam ◽  
Cross Sections ◽  
Level Density ◽  
Incident Beam ◽  
Mass Region ◽  
Cluster Decay ◽  
Compound System ◽  
Density Parameter ◽  
Relative Role ◽  
Level Density Parameter

This work deals with the decay analysis of three compound nuclei [Formula: see text], [Formula: see text] and [Formula: see text] formed in proton-induced reactions [Formula: see text], [Formula: see text] and [Formula: see text] at incident beam energies of 1–5 MeV using the Dynamical Cluster-decay Model (DCM). The motive is to explore the decay of compound systems formed via light charged particles as projectiles. The experimentally available data of n-evaporation for the aforementioned systems are addressed by optimizing the neck-length parameter [Formula: see text], using spherical fragmentation approach. The comparative analysis of the decay structure of the chosen systems is carried out at a common incident beam energy [Formula: see text] MeV. The effect of angular momentum [Formula: see text] and quadrupole [Formula: see text]-deformations is explored in reference to the decay structure/fragmentation of compound systems. In addition to this, the sensitivity of DCM-based cross-sections toward level density parameter (LDP) [Formula: see text] is also analyzed. The relative role of mass-dependent level density parameter [Formula: see text] is also investigated for compound systems belonging to light and heavy mass region. Lastly, a theoretical systematics is explored where the proton beam in the reaction [Formula: see text] is replaced by a neutron beam forming the compound system [Formula: see text], having the same [Formula: see text], but [Formula: see text] one less than that of the compound system formed in the reaction using proton beam, and its effect on the decay characteristics such as preformation probability, penetration probability and barrier height is analyzed.

scholarly journals On the isotopic composition of fission fragments

2021 ◽  
Vol 812 ◽  
pp. 136017
Author(s):  
C. Schmitt ◽  
P. Möller
Keyword(s):  
Isotopic Composition ◽  
Fission Fragments

scholarly journals Shell closure effects studied via cluster decay in heavy nuclei

2008 ◽  
Vol 36 (1) ◽  
pp. 015110 ◽  
Author(s):  
Sushil Kumar ◽  
Ramna Rani ◽  
Rajesh Kumar
Keyword(s):  
Cluster Decay ◽  
Shell Closure ◽  
Heavy Nuclei

scholarly journals Uncertainty Analysis of WWER-1000 Core Macroscopic Cross Sections due to Spectral Effects

2020 ◽  
pp. 39-46
Author(s):  
О. Kukhotska ◽  
I. Ovdiienko ◽  
M. Ieremenko
Keyword(s):  
Energy Spectrum ◽  
Isotopic Composition ◽  
Uncertainty Analysis ◽  
Neutron Flux ◽  
Flux Density ◽  
Cross Section ◽  
Cross Sections ◽  
Fuel Burnup ◽  
Thermophysical Parameters ◽  
Neutron Flux Density

The paper presents the results of uncertainty analysis of WWER‑1000 core macroscopic cross sections due to spectral effects during WWER‑1000 fuel burnup and the analysis of cross section sensitivity from thermophysical parameters of the calculated cell, which affect energy spectrum of neutron flux density. The calculation of changes in the isotopic composition during burnup and the preparation of macroscopic cross sections used the developed HELIOS computer model [1] for TVSA, which is currently operated at most Ukrainian WWER‑1000 units. The GRS approach applying Software for Uncertainty and Sensitivity Analyses (SUSA) [2] was chosen to assess the uncertainty of the macroscopic cross sections due to spectral effects and analysis of cross section sensitivity from thermophysical parameters. The spectral effect on macroscopic cross sections was taken into account by calculating the fuel burnup for variational sets of thermophysical parameters (fuel temperature, coolant temperature and density, boric acid concentration) prepared in advance by the SUSA program, as a result of which fuel isotopic composition vectors were obtained. After that, neutronic constants for the reference state were developed for each of the sets of isotopic composition, which corresponded to a certain set of thermophysical parameters. At the next stage, the uncertainty of macroscopic cross sections of the interaction due to the spectral effects on the isotopic composition of the fuel was analyzed using SUSA 4, followed by the analysis of cross section sensitivity from thermophysical parameters of the calculated cell affecting energy spectrum of neutron flux density. In the future, the uncertainty of two-group macroscopic diffusion constants can be used to estimate the overall uncertainty of neutronic characteristics in large-grid core calculations, in particular, in the safety analysis.

Particle entropy and depairing in hot nuclei

2016 ◽  
Vol 25 (11) ◽  
pp. 1650093 ◽  
Author(s):  
J. Dhivya Saranya ◽  
N. Boomadevi ◽  
T. R. Rajasekaran
Keyword(s):  
Single Particle ◽  
Mass Region ◽  
Shell Closure ◽  
Critical Temperatures ◽  
Level Densities ◽  
Hot Nuclei ◽  
Pairing Correlations ◽  
Experimental Values ◽  
Low Entropy ◽  
Interesting Analogy

The nuclear level densities and single particle entropies are predicted for nuclei in the mass region [Formula: see text] within a framework of statistical theory of hot nuclei method. In this method, particle-number and energy conservation as well as nuclear pairing correlations are included in the partition function of grand canonical ensemble. The suppression of pairing correlations is distinctly noticed in temperature dependence of entropies between the critical temperatures [Formula: see text] MeV and [Formula: see text] MeV for [Formula: see text], [Formula: see text] and [Formula: see text] isotopes of the elements. These structural thermodynamic entropies are interpreted as a remarkable signature of the superfluid to normal phase transition connected to the vanishing of pairing gap. The calculated level densities are compared with recent experimental values. In addition, the single particle entropy of intermediate-mass nuclei is depicted as half of the entropy of mid-shell nuclei in the rare-earth region. As a consequence, the [Formula: see text] shell closure of [Formula: see text]V carries low entropy at low excitation energy presents an interesting analogy to the [Formula: see text] shell closure of [Formula: see text]Ni. Merely, in the case of odd–even [Formula: see text] has higher entropy than the even–even [Formula: see text] nucleus.

scholarly journals Dissociative Recombination of CH+ Molecular Ion Induced by Very Low Energy Electrons

Atoms ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 82 ◽  
Author(s):  
Zsolt J. Mezei ◽  
Michel D. Epée Epée ◽  
Ousmanou Motapon ◽  
Ioan F. Schneider
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Incident Energy ◽  
Dissociative Recombination ◽  
Boltzmann Distribution ◽  
Rate Coefficients ◽  
Rotational States ◽  
Low Energy Electrons ◽  
Quantum Defect Theory ◽  
Π State

We used the multichannel quantum defect theory to compute cross sections and rate coefficients for the dissociative recombination of CH + initially in its lowest vibrational level v i + = 0 with electrons of incident energy below 0.2 eV. We have focused on the contribution of the 2 2 Π state which is the main dissociative recombination route at low collision energies. The final cross section is obtained by averaging the relevant initial rotational states ( N i + = 0 , ⋯ , 10 ) with a 300 K Boltzmann distribution. The Maxwell isotropic rate coefficients for dissociative recombination are also calculated for different initial rotational states and for electronic temperatures up to a few hundred Kelvins. Our results are compared to storage-ring measurements.

Polarisation et mesures de section efficace dans la réaction 9Be(3He, p)11B

1983 ◽  
Vol 61 (12) ◽  
pp. 1609-1612 ◽  
Author(s):  
J. Pouliot ◽  
R. Roy ◽  
P. Bricault ◽  
L. Potvin ◽  
R. J. Slobodrian
Keyword(s):  
Differential Cross Section ◽  
Cross Section ◽  
Differential Cross ◽  
Incident Energy ◽  
Section Efficace ◽  
Proton Polarization ◽  
Analyzing Powers ◽  
Nonuniform Illumination ◽  
Precise Knowledge ◽  
Correct Calculation

New measurements of the differential cross section have been carried out in the reaction 9Be(3He, p)11B between 13.0- and 14.2-MeV incident energy. In order to compute the effective analyzing powers of polarimeters used to measure proton polarization in the same reaction, a precise knowledge of angular variations is necessary. The achieved accuracy allows a correct calculation of the false asymmetry caused by nonuniform illumination of the analyser from cross section variations.

A Study on the New Empirical Cross Section Formulae for (γ, p) Reactions at 20 ± 1 MeV Incident Energy

2018 ◽  
Vol 37 (5) ◽  
pp. 270-274 ◽  
Author(s):  
E. Tel ◽  
Y. Kavun ◽  
M. Sahan ◽  
A. Aydin
Keyword(s):  
Cross Section ◽  
Incident Energy
Sign in / Sign up

Export Citation Format

Share Document