APPEARANCE OF FAST-FISSION AND QUASI-FISSION IN REACTIONS WITH MASSIVE NUCLEI

2005 ◽  
Vol 20 (06) ◽  
pp. 391-405 ◽  
Author(s):  
GIOVANNI FAZIO ◽  
GIORGIO GIARDINA ◽  
GIUSEPPE MANDAGLIO ◽  
FRANCIS HANAPPE ◽  
AKHTAM I. MUMINOV ◽  
...  
Keyword(s):  
Experimental Data ◽  
Reaction Mechanism ◽  
Excitation Function ◽  
Cross Sections ◽  
Neutron Emission ◽  
Evaporation Residue ◽  
Dinuclear System ◽  
Total Evaporation ◽  
Fast Fission ◽  
Evaporation Residues

The experimental data on the capture and evaporation residue cross-sections obtained in the 48 Ca +208 Pb reaction were analyzed in the framework of the dynamical model based on the dinuclear system concept and advanced statistical method to clarify the reaction mechanism. The experimental excitation function of the capture reactions was decomposed into contributions of the fusion–fission, quasifission and fast-fission processes. Total evaporation residues and ones after neutron emission were only calculated and compared with the available experimental data.

COMPARISON OF THE FUSION-FISSION AND QUASIFISSION MECHANISMS IN HEAVY-ION COLLISIONS

2009 ◽  
Vol 18 (04) ◽  
pp. 841-849 ◽  
Author(s):  
AVAZBEK NASIROV ◽  
GIOVANNI FAZIO ◽  
GIORGIO GIARDINA ◽  
GIUSEPPE MANDAGLIO ◽  
MARINA MANGANARO ◽  
...  
Keyword(s):  
Cross Sections ◽  
Theoretical Method ◽  
Heavy Ion ◽  
Evaporation Residue ◽  
System Model ◽  
Complete Fusion ◽  
Dinuclear System ◽  
Ion Collisions ◽  
Partial Fusion ◽  
Evaporation Residues

The decrease of the evaporation residue yields in reactions with massive nuclei is explained by an increase of the competition between quasifission and complete fusion processes and by the decrease of the survival probability of the heated and rotating nuclei against fission along the de-excitation cascade of the compound nucleus. The experimental data on the yields of evaporation residue, fusion-fission and quasifission fragments in the 48 Ca + 154 Sm reaction are analyzed in the framework of the combined theoretical method based on the dinuclear system concept and advanced statistical model. The measured yields of evaporation residues of the 48 Ca + 154 Sm reaction have been well reproduced and yields of fission fragments were analyzed using the partial fusion and quasifission cross sections calculated in the dinuclear system model. Such a way of calculation is used to find optimal conditions for the synthesis of the new element Z = 120 (A = 302) by studying the excitation functions of evaporation residues of the 54 Cr + 248 Cm , 58 Fe + 244 Pu , and 64 Ni + 238 U reactions. Our estimations show that the 54 Cr + 248 Cm reaction is preferable in comparison with the two others.

Investigation of the synthesis of the unknown superheavy nuclei 309,312126

2019 ◽  
Vol 28 (07) ◽  
pp. 1950056 ◽  
Author(s):  
T. V. Nhan Hao ◽  
N. N. Duy ◽  
K. Y. Chae ◽  
N. Quang Hung ◽  
N. Nhu Le
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Charge Asymmetry ◽  
Evaporation Residue ◽  
Fission Process ◽  
Dinuclear System ◽  
Mass Asymmetry ◽  
Interacting Systems ◽  
First Time ◽  
Text Element

In this paper, we applied the method developed by Santhosh and Safoora in [Phys. Rev. C  94 (2016) 024623; 95 (2017) 064611] to theoretically investigate the fusion, evaporation-residue (ER) and fission cross-sections of the synthesis of the unknown superheavy [Formula: see text]126 nuclei produced by using the [Formula: see text]Ni + [Formula: see text]Cf and [Formula: see text]Zn + [Formula: see text]Cm combinations. The charge asymmetry, mass asymmetry and fissility of the DiNuclear System (DNS) in the synthesis of the mentioned combinations are also estimated. The calculated results show that the ER cross-sections for the synthesis of the [Formula: see text]126 nuclei are predicted to be much less than 1.0[Formula: see text]fb. In particular, it has been found that there may exist a valley of the ER cross-sections in the synthesis of a superheavy [Formula: see text] element, which produces the [Formula: see text]126 isotope. Subsequently, a model for the mass dependence of the ER cross-section in the synthesis of the [Formula: see text]126 isotopes has been proposed for the first time. On the other hand, the quasi-fission process strongly dominates over the fusion in the two concerned interacting systems. The present results, together with those reported in the previous studies, indicate that the investigated projectile–target combinations are not capable for the synthesis of the [Formula: see text]126 isotopes due to tiny fusion cross-sections (about 2–3[Formula: see text]zb), which go beyond the limitations of available facilities. Further studies are thus recommended to search for alternative interacting systems. In conclusion, this work provides useful information for the synthesis of the gap isotopes [Formula: see text]126, which have not been well studied up to date.

COLD FUSION REACTIONS USING NEUTRON-RICH PROJECTILES

2013 ◽  
Vol 22 (08) ◽  
pp. 1350061 ◽  
Author(s):  
A. SULAKSONO
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Estimation Method ◽  
Cold Fusion ◽  
Evaporation Residue ◽  
Fusion Reactions ◽  
Fusion Barrier ◽  
The Cross ◽  
Evaporation Residues

This paper studies the formation cross-sections of super heavy (SH) nuclei in some cold fusion reactions of radioactive neutron-rich projectiles with double-magic 208 Pb target. In this study, the cross-sections of capture, fusion and evaporation residues in one- and two-neutron (1n and 2n) channels are calculated by using neutron-rich Fe , Ni and Zn projectiles are compared to the cross-sections calculated using stable Fe , Ni and Zn projectiles. The heights of fusion barrier and their positions in all reactions considered in this study are also compared to the heights and positions calculated using the estimation method proposed by Dutt and Puri. For cold fusion reactions with stable Fe , Ni and Zn projectiles, the heights of fusion barrier and the cross-sections of evaporation residues in 1n and 2n channels are compared to their corresponding experimental data. In general, for reactions using projectiles with the same proton number, the neutron-rich projectile is found to yield relatively-heavier mass of SH nucleus and larger evaporation residue cross-section, compared to those of the corresponding stable projectiles. However, in certain reactions, the cross-sections of neutron-rich projectile can be slightly larger or slightly smaller than that of the corresponding stable projectile. This behavior is highly affected by the charge of projectile and the fission barrier of the formed compound nucleus (CN). In addition, the 292114 is found to be the heaviest compound nucleus formed in cold fusion reaction by using neutron-rich nuclei as the projectile, but the cross-section of evaporation residue in one-neutron channel is still around few pico barns (pb).

PRE-EQUILIBRIUM EMISSION IN DIFFERENTIAL CROSS-SECTION CALCULATIONS AND ANALYSIS OF EXPERIMENTAL DATA FOR 232Th

2004 ◽  
Vol 19 (21) ◽  
pp. 1597-1614 ◽  
Author(s):  
E. TEL ◽  
İ DEMİRKOL ◽  
A. ARASOĞLU ◽  
B. ŞARER
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Neutron Emission ◽  
Emission Spectra ◽  
Exciton Model ◽  
Quantum Mechanical Theory ◽  
Geometry Dependent Hybrid Model ◽  
Neutron Emission Spectra ◽  
Equilibrium Matrix ◽  
Equilibrium Emission

In this study, neutron-emission spectra produced by (n,xn) reactions on nuclei 232 Th have been calculated. Angle-integrated cross-sections in neutron induced reactions on targets 232 Th have been calculated at the bombarding energies from 2 MeV to 18 MeV. We have investigated multiple pre-equilibrium matrix element constant from internal transition for 232 Th (n,xn) neutron emission spectra. In the calculations, the geometry dependent hybrid model and the cascade exciton model including the effects of pre-equilibrium have been used. Pre-equilibrium direct effects have been examined by using full exciton model. In addition, we have described how multiple pre-equilibrium emissions can be included in the Feshbach–Kerman–Koonin (FKK) fully quantum-mechanical theory. By analyzing (n,xn) reaction on 232 Th , with the incident energy from 2 MeV to 18 MeV, the importance of multiple pre-equilibrium emission can be seen clearly. All calculated results have been compared with experimental data. The obtained results have been discussed and compared with the available experimental data and found agreement with each other.

NEUTRON EVAPORATION IN THE 14-MEV NEUTRON FISSION OF URANIUM

1961 ◽  
Vol 39 (7) ◽  
pp. 967-975 ◽  
Author(s):  
G. C. Hanna ◽  
R. L. Clarke
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Neutron Emission ◽  
Neutron Energy Spectrum ◽  
Measured Intensity ◽  
Neutron Fission ◽  
Fission Fragments ◽  
Neutron Evaporation ◽  
Neutron Multiplicities ◽  
Calculated Number

The numbers of prefission and postfission neutrons expected from the 14-Mev neutron fission of uranium have been calculated from the experimental data on partial cross sections and neutron multiplicities. It has been assumed that the competition between neutron emission and fission does not change with increasing energy beyond threshold. The neutron energy spectrum measured recently by Clarke gives a smaller intensity in the energy range 4–6 Mev than is expected from the calculated number of postfission neutrons. The measured intensity suggests that only 2.1 ± 0.5 neutrons are evaporated from the moving fission fragments.

Production cross-sections of superheavy elements using nearly double magic nuclei as projectile

2017 ◽  
Vol 26 (07) ◽  
pp. 1750050
Author(s):  
Ahmad Ansari ◽  
Nader Ghahramany
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Production Cross ◽  
Evaporation Residue ◽  
Fission Barrier ◽  
Superheavy Nuclei ◽  
New Approach ◽  
Barrier Heights ◽  
Compound Nucleus Formation ◽  
Good Agreement

In our new approach, evaporation residue cross-sections for new superheavy nuclei with atomic numbers [Formula: see text] are estimated by calculation of vital characteristics of superheavy nuclei synthesis such as the fission barrier height, the compound nucleus formation probability and the survival probability of the residue nuclei. Our presented estimation is in good agreement with available experimental data. In addition, this new approach allowed us to predict the evaporation residue cross-sections for superheavy nuclei with [Formula: see text] and 120 via introducing synthesis box and compare our results with other models. It is shown that the fission barrier heights of two nuclei with [Formula: see text] and 120 are comparable with their corresponding neutron separation energies. It is suggested that for the synthesis of new superheavy nuclei, it is proper to use nearly double magic nuclei such as [Formula: see text] as our projectile, so that the fission barrier heights remain high.

scholarly journals Measuring precise fusion cross sections using an 8T superconducting solenoid

2020 ◽  
Vol 232 ◽  
pp. 03003
Author(s):  
L. T. Bezzina ◽  
E. C. Simpson ◽  
D. J. Hinde ◽  
M. Dasgupta ◽  
I. P. Carter ◽  
...  
Keyword(s):  
Angular Distribution ◽  
Cross Sections ◽  
Laboratory Frame ◽  
Transmission Efficiency ◽  
Evaporation Residue ◽  
Angular Distributions ◽  
The Novel ◽  
Superconducting Solenoid ◽  
National University ◽  
Evaporation Residues

A novel fusion-evaporation residue separator based on a gas-filled superconducting solenoid has been developed at the Australian National University. Though the transmission efficiency of the solenoid is very high, precision cross sections measurements require this efficiency to be accurately known and vitally, requires knowledge of the angular distribution of the evaporation residues. We have developed a method to deduce the angular distribution of the evaporation residues from the laboratory-frame velocity distribution of the evaporation residues transmitted by the solenoid. The method will be discussed, focusing on benchmarking examples for 34S+89Y, where the angular distributions have been independently measured using a velocity filter (A. Mukherjee et al., Phys. Rev. C. 66, 034607 (2002)) . The establishment of this method now allows the novel solenoidal separator to be used to obtain reliable, precise fusion cross-sections.

scholarly journals The Dipole States of Mas?11 Nuclei

1973 ◽  
Vol 26 (1) ◽  
pp. 7 ◽  
Author(s):  
BM Spicer ◽  
RF Fraser
Keyword(s):  
Experimental Data ◽  
Excitation Function ◽  
Electron Scattering ◽  
Cross Sections ◽  
Inelastic Electron ◽  
Inelastic Electron Scattering

Calculations of the even parity states of mass-ll nuclei in the 1p-2h basis are presented and the results are compared with experimental data from inelastic electron scattering, the llB(y, n) and llB(y, p) cross sections, and the lOB(p, Yo) excitation function.

SHELL CORRECTION ENERGIES IN CALCULATIONS OF THE SURVIVAL PROBABILITY

2005 ◽  
Vol 14 (03) ◽  
pp. 333-339 ◽  
Author(s):  
K. SIWEK-WILCZYŃSKA ◽  
I. SKWIRA ◽  
J. WILCZYŃSKI
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Ground State ◽  
Evaporation Residue ◽  
Shell Correction ◽  
Model Calculations ◽  
Shell Effects ◽  
Fission Barriers ◽  
Shell Correction Energy ◽  
Existing Data

Analysis of existing data on experimental fission barriers for about 90 nuclei shows that the shell correction energy practically vanishes at the barrier configuration. Statistical model calculations, with shell effects accounted for by the Ignatyuk formula, were carried out for the decay of the 248 Cf compound nucleus assuming the ground state shell corrections of Möller et al., and the vanishing shell correction energy at the barrier. The results are consistent with existing experimental data on fusion- and xn evaporation-residue cross sections in the 12 C +236 U reaction.

scholarly journals Relativistic B-Spline R-Matrix Calculations for Electron Collisions with Ytterbium

Atoms ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 47
Author(s):  
Kathryn R. Hamilton ◽  
Klaus Bartschat ◽  
Oleg Zatsarinny
Keyword(s):  
Experimental Data ◽  
Electron Scattering ◽  
Cross Sections ◽  
Matrix Method ◽  
Model Potential ◽  
Electron Collisions ◽  
R Matrix ◽  
B Spline ◽  
Potential Approach

We have applied the full-relativistic Dirac B-Spline R-matrix method to obtain cross sections for electron scattering from ytterbium atoms. The results are compared with those obtained from a semi-relativistic (Breit-Pauli) model-potential approach and the few available experimental data.

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