A comparative study of α-decay and spontaneous fission for Z = 120 superheavy isotopes

2020 ◽  
Vol 29 (05) ◽  
pp. 2050025
Author(s):  
S. A. Seyyedi
Keyword(s):  
Binding Energy ◽  
Comparative Study ◽  
Spontaneous Fission ◽  
Decay Chain ◽  
Superheavy Nuclei ◽  
Empirical Formulas ◽  
Α Decay ◽  
Hartree Fock ◽  
Effective Force ◽  
Semi Empirical

In this study, we have investigated the [Formula: see text]-decay chains of even–even superheavy nuclei [Formula: see text] in the range of [Formula: see text]. The Hartree–Fock–Bogoliubov model is used to calculate the binding energy of these superheavy nuclei. We have included the so-called SkP skyrme function as an effective force and the quadruple deformations. The semi-empirical formulas are used in the reproducing [Formula: see text]-decay and spontaneous fission half-lives of these superheavy nuclei. By studying the decay chains of the Z = 120 isotopes and comparing them with the half-lives of spontaneous fission, it is predicted that the elements [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text],[Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are more stable than the neighboring isotopes in their parent [Formula: see text]-decay chain. The corresponding neutron and proton numbers represent magical behavior that is in agreement with the numbers predicted before. In this range, the predicted nuclei are found to have large enough half-lives to synthesize them in a laboratory.

Examination of α-decay half-lives of undetected transfermium isotopes

2020 ◽  
Vol 29 (10) ◽  
pp. 2050085
Author(s):  
Nguyen Nhu Le ◽  
Nguyen Ngoc Duy
Keyword(s):  
Half Life ◽  
Spontaneous Fission ◽  
Theoretical Calculations ◽  
Q Value ◽  
Calculation Methods ◽  
Α Decay ◽  
Decay Modes ◽  
Predicted Values ◽  
Semi Empirical ◽  
Q Values

This study reports the [Formula: see text]-decay half-lives of 39 transfermium isotopes with [Formula: see text], most of which have not been observed. The half-lives were calculated using micro–macroscopic approaches and semi-empirical formulae, applying current [Formula: see text]-decay Q-values from the latest mass database, AME2016. These results were compared to predicted values in previous works to evaluate the efficiency of and difference between various calculation methods. We found that the [Formula: see text]-resonance approach used in a previous study is not appropriate to predict though most other approaches are mutually consistent. An uncertainty of 70% was observed in the present theoretical calculations, similar to that observed in measurements. A Q-value uncertainty of 10% can lead to a large variation of 3 orders of magnitude in predicted [Formula: see text]-decay half-life. We also found that the dominance of either [Formula: see text] decay or spontaneous fission is unclear for the isotopes with [Formula: see text]–[Formula: see text], whereas most of the nuclei of [Formula: see text]–[Formula: see text] can be clearly identified as [Formula: see text] emitters. Finally, we provide the updated [Formula: see text]-decay half-lives for the isotopes of interest, including their uncertainties and corresponding decay modes.

SYNTHESIS OF HEAVIEST ELEMENTS (RESULTS AND PROSPECTS)

2007 ◽  
Vol 16 (04) ◽  
pp. 949-956 ◽  
Author(s):  
YURI OGANESSIAN
Keyword(s):  
Cosmic Rays ◽  
Spontaneous Fission ◽  
Radioactive Decay ◽  
Superheavy Element ◽  
Parent Nucleus ◽  
Superheavy Nuclei ◽  
Α Decay ◽  
Decay Properties ◽  
Neutron Rich Isotope ◽  
Heaviest Elements

The formation and decay properties of the heaviest nuclei with Z = 112 - 116 and 118 were studied in the reactions 238 U , 242,244 Pu , 243 Am , 245,248 Cm and 249 Cf +48 Ca . The new nuclides mainly undergo sequential α-decay, which ends with spontaneous fission. The total time of decays ranges from 0.5 ms to about 1 day, depending on the proton and neutron numbers in the synthesized nuclei. The atomic number of the new elements 115 and 113 was confirmed also by an independent radiochemical experiment based on the identification of the neutron-rich isotope 268 Db (TSF ≈ 30 h ), the final product in the chain of α-decays of the odd–odd parent nucleus 288115. The comparison of the decay properties of 29 new nuclides with Z = 104 - 118 and N = 162 - 177 gives evidence for the decisive influence of the structure of superheavy nuclei on their stability with respect to different modes of radioactive decay. The investigations connected with the search for superheavy elements in Nature (cosmic rays) and prospects of superheavy element research are also presented.

Alpha decay and spontaneous fission in superheavy isotopes, Z = 124, using a density-dependent cluster model

2020 ◽  
pp. 2050096
Author(s):  
S. A. Seyyedi
Keyword(s):  
Empirical Formula ◽  
Half Life ◽  
Cluster Model ◽  
Spontaneous Fission ◽  
Alpha Decay ◽  
Nucleon Nucleon ◽  
Empirical Formulas ◽  
Density Dependent ◽  
Double Folding ◽  
Semi Empirical

Alpha decay (AD) and spontaneous fission (SF) half-lives of superheavy nuclei [Formula: see text] have been studied within the density-dependent cluster model. The alpha-nucleus potentials were calculated using the double-folding model with the realistic M3Y nucleon–nucleon interaction. To calculate nuclear half-lives, several semi-empirical formulas were used in addition to the Wentzel–Kramers–Brillouin (WKB) approximation. The calculated AD half-lives agree well with the values computed by the analytical formulas of Royer, the semi-empirical formula of Poenaru et al. and the Viola–Seaborg systematic. To identify the mode of decay of these nuclei, the SF half-lives were calculated using the semi-empirical formula given by Xu et al. The results show that among the isotopes studied, isotopes [Formula: see text] can be survived from the SF and have a half-life greater than [Formula: see text][Formula: see text](s). The study predicts [Formula: see text] chains from isotopes [Formula: see text], [Formula: see text] chains from isotopes [Formula: see text], [Formula: see text] chains from isotopes [Formula: see text] and an AD from [Formula: see text]. These isotopes have a half-life long enough to be synthesized in the laboratory. Also, in the decay chains of these isotopes, it is observed that the nuclei [Formula: see text] have higher half-lives than their neighbors. The neutron numbers corresponding to these isotopes are [Formula: see text] indicating the magical or semi-magical behavior of these numbers, which is in good agreement with the research results.

Stability of superheavy nuclei against α-decay and spontaneous fission

2013 ◽  
Vol 898 ◽  
pp. 24-31 ◽  
Author(s):  
Chang Xu ◽  
Xin Zhang ◽  
Zhongzhou Ren
Keyword(s):  
Spontaneous Fission ◽  
Superheavy Nuclei ◽  
Α Decay

Models of Electron-Hole Screening and Exciton Binding in Conjugated Polymers

1995 ◽  
Vol 413 ◽  
Author(s):  
David Yaron ◽  
Eric Moore ◽  
Benjamin Gherman
Keyword(s):  
Binding Energy ◽  
Conjugated Polymers ◽  
Point Charge ◽  
Solvation Energy ◽  
Exciton Binding Energy ◽  
Electron Interaction ◽  
Electron Hole ◽  
Relative Time ◽  
Hartree Fock ◽  
Semi Empirical

ABSTRACTThe use of semi-empirical quantum chemistry to calculate the exciton binding energy of conjugated polymers is discussed. Both the Pariser-Parr-Pople (PPP) model with Ohno parameterization and the models present in the MOPAC program overestimate the exciton binding energy relative to that observed in solid-state materials. Inclusion of Coulomb screening from adjacent chains may correct this overestimation. The solvation energy of a point charge in polyacetylene is calculated as 0.9eV, using Hartree-Fock theory to describe the polarization induced in the solvent chains. It is argued that including screening by modifying the electron-electron interaction energy of the PPP model introduces physically unreasonable side effects and is not consistent with the 0.9eV solvation energy of a point charge. Electron-hole screening models are then discussed along with the need to consider the relative time scales of the electron-hole motion and the dielectric response.

PROPERTIES OF SUPERHEAVY NUCLEI IN VARIOUS MACROSCOPIC-MICROSCOPIC MODELS

2005 ◽  
Vol 14 (03) ◽  
pp. 365-372 ◽  
Author(s):  
A. BARAN ◽  
M. KOWAL ◽  
Z. ŁOJEWSKI ◽  
K. SIEJA
Keyword(s):  
Spontaneous Fission ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Electric Quadrupole ◽  
Superheavy Nuclei ◽  
Quadrupole Moments ◽  
Α Decay ◽  
Macroscopic Models ◽  
Microscopic Models ◽  
Three Dimensional Space

In the framework of various macroscopic-microscopic models we examine the ground state properties: separation energies, mean square charge radii, electric quadrupole moments as well as fission barriers, mass parameters, spontaneous fission and α decay half-lives of superheavy nuclei. Four macroscopic models and two models of pairing interactions are applied and studied. The approach is based on the deformed Woods-Saxon potential. Spontaneous fission half-lives are calculated within a multi-dimensional dynamical-programming method where the action integral is minimized within the three dimensional space of the nuclear deformation parameters {β2, β4, β6}.

Spontaneous fission of the end product in α-decay chain of recoiled superheavy nucleus: A theoretical study

2018 ◽  
Vol 27 (05) ◽  
pp. 1850043 ◽  
Author(s):  
Amandeep Kaur ◽  
Gudveen Sawhney ◽  
Manoj K. Sharma ◽  
Raj K. Gupta
Keyword(s):  
Cluster Model ◽  
Spontaneous Fission ◽  
Theoretical Study ◽  
Superheavy Nucleus ◽  
Decay Chain ◽  
Temperature Dependent ◽  
Α Decay ◽  
Mass Distributions ◽  
Shell Closures ◽  
End Products

The temperature-dependent preformed cluster model [PCM[Formula: see text]] is employed to extend our recent work [Niyti, G. Sawhney, M. K. Sharma and R. K. Gupta, Phys. Rev. C 91 (2015) 054606] on [Formula: see text]-decay chains of various isotopes of [Formula: see text]–118 superheavy nuclei (SHN), to spontaneous fissioning nuclei [Formula: see text]Lr, [Formula: see text]Rf, [Formula: see text]Db, [Formula: see text]Rg, and [Formula: see text]Cn occurring as end products of these [Formula: see text]-decay chains. The behavior of fragment mass distribution and competitive emergence of the dominant decay mode, i.e., the [Formula: see text]-emission versus spontaneous fission (SF), are studied for identifying the most probable heavy fission fragments, along with the estimation of SF half-life times T[Formula: see text] and total kinetic energy (TKE) of the above noted isotopes of [Formula: see text]–112 nuclei decaying via the SF process. The mass distributions of chosen nuclei are clearly symmetric, independent of mass and temperature. The most preferred decay fragment is found to lie in the neighborhood of doubly magic shell closures of [Formula: see text] and [Formula: see text], with largest preformation factor [Formula: see text]. In addition, a comparative study of the “hot compact” and “cold elongated” configurations of [Formula: see text]-deformed and [Formula: see text]-oriented nuclei indicates significantly different behaviors of the two mass fragmentation yields, favoring “hot compact” configuration.

On the Stability of Superheavy Nuclei against Fission, Alpha Decay and Electron Capture

1971 ◽  
Vol 26 (4) ◽  
pp. 643-652 ◽  
Author(s):  
Jens Grumann ◽  
Tihomir Morovic ◽  
Walter Greiner
Keyword(s):  
Potential Energy ◽  
Electron Capture ◽  
Spontaneous Fission ◽  
Energy Surface ◽  
Liquid Drop ◽  
Alpha Decay ◽  
Superheavy Nuclei ◽  
Liquid Drop Model ◽  
Α Decay ◽  
The Stability

AbstractThe potential energy surface has been calculated by two methods which are compared with re­spect to spontaneous fission. In the first one essentially the sum of the single particle energies is computed as was done in a previous paper3 while in the second one the Strutinsky technique of renormalizing to a liquid drop model has been applied. Also the half-lives for electron capture are investigated together with the predictions of the half-lives for spontaneous fission and α-decay. The results support the existence of superheavy nuclei in the regions around Z = 114 and Z = 164.

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