BINARY AND TERNARY EMISSION FROM SUPERHEAVY NUCLEI

2008 ◽  
Vol 17 (10) ◽  
pp. 2221-2225 ◽  
Author(s):  
RADU A. GHERGHESCU ◽  
DORIN N. POENARU ◽  
WALTER GREINER
Keyword(s):  
Shell Model ◽  
Liquid Drop ◽  
Parent Nucleus ◽  
Exponential Model ◽  
Deformation Energy ◽  
Superheavy Nuclei ◽  
Multidimensional Space ◽  
Total Deformation ◽  
Cluster Emission ◽  
Deformation Dynamics

The two center shell model is used to calculate the level scheme transition from the superheavy parent nucleus to the emitted cluster plus the daughter nucleus. The three center shell model is also employed to compute the transition toward eventual three equal fragment partition from the superheavy nuclei. The levels are used to compute the shell corrections within the Strutinsky method. The liquid drop part is calculated using the Yukawa-plus-exponential model. The total deformation energy is then minimized over a multidimensional space of deformation. Dynamics is completed with the Werner-Wheeler tensor calculation, and cluster emission paths for binary and ternary splitting is obtained for Z = 120 isotopes.

Two-proton radioactivity within Coulomb and proximity potential model

2021 ◽  
Author(s):  
De-Xing Zhu ◽  
Hong-Ming Liu ◽  
Yang-Yang Xu ◽  
You-Tian Zou ◽  
Xi-Jun Wu ◽  
...  
Keyword(s):  
Potential Model ◽  
Liquid Drop ◽  
Theoretical Models ◽  
Parent Nucleus ◽  
Drip Line ◽  
Liquid Drop Model ◽  
Empirical Formulas ◽  
Proximity Potential ◽  
Proton Radioactivity ◽  
Good Agreement

Abstract In the present work, considering the preformation probability of the emitted two protons in the parent nucleus, we extend the Coulomb and proximity potential model (CPPM) to systematically study two-proton (2p) radioactivity half-lives of the nuclei close to proton drip line, while the proximity potential is chosen as Prox.81 proposed by Blocki et al. in 1981. Furthermore, we apply this model to predict the half-lives of possible 2p radioactive candidates whose 2p radioactivity is energetically allowed or observed but not yet quantified in the evaluated nuclear properties table NUBASE2016. The predicted results are in good agreement with those from other theoretical models and empirical formulas, namely the effective liquid drop model (ELDM), generalized liquid drop model (GLDM), Gamow-like model, Sreeja formula and Liu formula.

CHARGE DENSITY INFLUENCE ON MACROSCOPIC DEFORMATION ENERGY

2010 ◽  
Vol 19 (07) ◽  
pp. 1411-1423
Author(s):  
R. A. GHERGHESCU ◽  
D. N. POENARU ◽  
M. RAPORTARU ◽  
B. POPOVICI ◽  
W. GREINER
Keyword(s):  
Potential Energy ◽  
Charge Density ◽  
Density Dependence ◽  
Exponential Model ◽  
Deformation Energy ◽  
Proton Density ◽  
Macroscopic Deformation

A formula describing the proton density dependence on macroscopic deformation energy for different fusion-like shape configurations is derived. As a consequence, the influence of intermediary atomic numbers of fusioning nuclei on the macroscopic deformation-dependent terms of the potential energy in the Yukawa-plus-exponential model is studied. For the same target–projectile pair, at the same distance between their centers, macroscopic fusion barriers differ by energy amounts up to 5 MeV.

scholarly journals MACROSCOPIC-MICROSCOPIC ENERGY OF ROTATING NUCLEI IN THE FUSION-LIKE DEFORMATION VALLEY

2000 ◽  
Vol 09 (01) ◽  
pp. 51-66 ◽  
Author(s):  
RADU A. GHERGHESCU ◽  
GUY ROYER
Keyword(s):  
Shell Model ◽  
Liquid Drop ◽  
Fission Barrier ◽  
Liquid Drop Model ◽  
Potential Barriers ◽  
Angular Momenta ◽  
Microscopic Origin ◽  
Microscopic Energy ◽  
Rotating Nuclei

The energy of rotating nuclei in the fusion-like deformation valley has been determined within a liquid drop model including the proximity energy, the two-center shell model and the Strutinsky method. The potential barriers of the 84 Zr , 132 Ce , 152 Dy and 192 Hg nuclei have been determined. A first minimum having a microscopic origin and lodging the normally deformed states disappears with increasing angular momenta. The microscopic and macroscopic energies contribute to generate a second minimum where superdeformed states may survive. It becomes progressively the lowest one at intermediate spins. At higher angular momenta, the minimum moves towards the foot of the external fission barrier leading to hyperdeformed quasi-molecular states.

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.

DYNAMICAL HINDRANCE OF FUSION OF SUPERHEAVY NUCLEI

2006 ◽  
Vol 15 (02) ◽  
pp. 426-431 ◽  
Author(s):  
J. BŁOCKI ◽  
L. SHVEDOV ◽  
J. WILCZYŃSKI
Keyword(s):  
Saddle Point ◽  
White Noise ◽  
Coulomb Barrier ◽  
Cold Fusion ◽  
Langevin Equations ◽  
Superheavy Nuclei ◽  
Multidimensional Space ◽  
Fusion Reactions ◽  
Dissipative Forces ◽  
Fusion Probability

The dynamical hindrance of fusion after the system of two colliding nuclei overcomes the Coulomb barrier is calculated. Langevin equations, in which the stochastic white noise is added to the conservative and dissipative forces, are solved in the multidimensional space. It is shown that in case of very heavy systems the dynamical trajectories lead from the Coulomb barrier towards the fission valley at locations rather outside the saddle point and then turn downward to scission. Only due to fluctuations a small fraction of trajectories can overcome the saddle point and lead to fusion. Fusion probabilities determined by the ratio of fusion-to-scission fluxes are calculated. In cold fusion reactions induced by different projectiles on 208 Pb and 209 Bi targets, the fusion probability drops down by almost ten orders of magnitude for a range of projectiles from 48 Ca (Zcn = 102) to 86 Kr (Zcn = 118).

TRIAXIAL REFLECTION ASYMMETRIC SHELL MODEL

2008 ◽  
Vol 17 (supp01) ◽  
pp. 146-158 ◽  
Author(s):  
Y. S. CHEN ◽  
Z. C. GAO
Keyword(s):  
Shell Model ◽  
Transition Probabilities ◽  
Mean Field ◽  
Negative Parity ◽  
Laboratory Frame ◽  
Superheavy Nuclei ◽  
Tetrahedral Symmetry ◽  
State Band ◽  
Natural Way ◽  
Good Agreement

The spontaneously broken reflection and axial symmetries in the nuclear mean field and their necessary restorations in the laboratory frame are described in a natural way in the triaxial Reflection Asymmetric Shell Model. This recently developed theoretical model has been applied to explore the possibility that some superheavy nuclei may have an exotic shape, tetrahedral-like. The ground state band and the partner low-lying negative parity bands are calculated for the Cf isotopes and the results are in a good agreement with the available experimental data. The tetrahedral symmetry, realized at the first order with the nonaxial octupole Y 32 deformation, plays an important role for understanding the low-lying band structures in transfermium and superheavy nuclei, but it is significantly obscured by the competing quadrupole deformation as well as the axial octupole component. The calculated reduced E3 transition probabilities between the low lying 2–-band states and the ground band states show a large enhancement of the nonaxial octupole collectivity.

A New Mesh Moving Technique for a Fluid–Structure Interaction Problem Using Mesh Deformation Energy Minimization

2019 ◽  
Vol 18 (01) ◽  
pp. 1950039
Author(s):  
Sahuck Oh
Keyword(s):  
Outer Boundary ◽  
Deformation Energy ◽  
Target Object ◽  
Tetrahedral Mesh ◽  
Mesh Deformation ◽  
Total Deformation ◽  
Deformation Method ◽  
Boundary Points ◽  
Elasticity Equations ◽  
Initial Mesh

When mesh boundaries move in a simulation because of the motion of a target object such as translation, rotation, and oscillation, the mesh should be regenerated to the points it will obey the locations of its new boundaries. Because recreating new mesh from the beginning is a time-consuming task, new mesh is usually created by deforming an initial mesh, which is called the mesh moving method (or mesh deformation method). In this paper, we present a new mesh moving method that produces a higher quality deformed mesh than the current mesh moving methods. In the proposed method, the deformation of mesh is evaluated by two energy quantities that are related to (i) the distortion of mesh that is invariant to translation, rotation, and size changes of the elements of the mesh and (ii) the deformation of mesh calculated using elements’ size based on stiffened-linear elasticity equations. The total deformation energy of mesh is defined as a weighted sum of these two quantities. Because there is no need to pre-fix the locations of the outer boundary points for most mesh moving problems, we use new constraints, allowing the outer boundary points to move along tangential directions in the proposed method. The deformed mesh is computed by calculating the positions of the mesh points where the total deformation energy of the mesh is minimized. For test purposes, the proposed method is applied to 2D triangular meshes and a 3D tetrahedral mesh, where the meshes are deformed by the motions of the target objects such as translation, rotation, and deformation. When the quality of the deformed meshes computed with the proposed method are compared with the ones computed with current mesh moving methods, the meshes from the proposed method are shown to be better than the other meshes.

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