Alpha decay energies and half-lives for possibly synthesized superheavy elements

We investigate the ground state properties of some superheavy nuclei, which may be synthesized in future experiments. Special emphases are placed on the alpha decay energies and half-lives. The alpha decay energies and half-lives from different theoretical models are compared and discussed comprehensively. Through these calculations and comparisons, the optimal superheavy elements to be synthesized in future experiments are proposed theoretically.

Calculation of α decay half-lives for superheavy elements using the double folding model

α decay half-lives of some new synthesized superheavy elements, possibly synthesized superheavy elements and decay products are calculated theoretically within the WKB approximation by using microscopic α-nucleus interaction potentials. These nuclear potentials between the α particle and daughter nuclei are obtained by using the double folding integral of the matter density distribution of the α particle and daughter nuclei with a density-dependent effective nucleon-nucleon interaction, in which the zero-range exchange term is supplemented. The calculated α decay half-lives are compared with those of the different models and experimental data. It is shown that the present calculation successfully provides the half-lives of the observed decays for some new superheavy elements and therefore gives reliable predictions for α decay of possibly synthesized superheavy elements in future experiments.

The entrance channel effect on the synthesis of a superheavy element ^(296)119

In this study,we investigated the entrance channel effect on the evaporation residue cross section of a superheavy element^(296)119.Using 29 projectile-target combinations,we investigated the role of the entrance channel on the 3n and 4n evaporation channels in hot combinations.This effect can be evaluated based on the entrance channel asymmetry and Q value of complete fusion.We calculated the variation of the maximum evaporation residue cross sections(σ^(max)_(3n)andσ^(max)_(4n))with|Q|for the reactions^(49-47)Ti+^(247-249)Bk,^(60-57)Fe+^(236-239)Np,^(44-42)Ca+^(252-254)Es,and^(55,54,52)Mn+^(241,242,244)Pu.With an increase in|Q|,σ^(max)_(3n)andσ^(max)_(4n) increase.In addition,we studied the role of asymmetry and mean fissility parameters in the synthesis of the superheavy element.The obtained results in this study can be utilized in future studies.

Explanation of Cold Nuclear Fusion and Biotransmutations

Low energy nuclear reactions are possible in condensed matter because of image forces. They result from induced charges at the surface of metals or very polarizable media. The height and width of the Coulomb barrier in free space can thus be reduced. Nuclear fusion requires also the formation of a compound nucleus in one of its excited states, but two deuterons yield an α particle that has 2 excited states. They are respectively accessible at high or low energies. Since the reduction of the Coulomb barrier depends on the local curvature of the interface, cold fusion becomes autocatalytic, but heat production is controllable. Even microbes, plants and animals can produce transmutations. They are also due to image forces. This solves a basic problem in nuclear physics and there are possible applications: facilitated synthesis of superheavy elements and development of a new type of energy sources. They are moderate, but safe.

The Average Lifetime of Giant Composite Systems Formed in Strongly Damped Collisions

The dynamic, adiabatic and diabat ic entrance potentials in strongly damped reactions of ^238 U＋^238 U, ^232 Th ＋ ^250Cf are calculated and compared. The feature of the dynamical potential implies that it is possible for the composite systems to stick together for a period of time. By means of the improved quantum molecular dynamics model the time evolution of the density and charge distributions of giant composite systems and their fragments for reactions ^238U＋^238U, ^232Th＋^250Cf are investigated, from which the lifetimes of giant composite systems at different energies are obtained. The longest average lifetime of ^238U＋^238U is found when the incident energy is about Ec.m =1080 MeW, which is about 1200 fm/c.

Effects of triaxial deformation on the fission barrier in the Z=118−120 nuclei

By using potential energy surface(PES)calculations in the three-dimensional space(β_(2),γ,β_(4))within the framework of the macroscopic-microscopic model,the fission trajectory and fission barrier for Z=118(Og),119,120 nuclei has been systematically investigated.The calculated PES includes macroscopic liquid-drop energy,microscopic shell correction and pairing correction.Taking the ^(294)Og176 nucleus as an example,we discuss the next closed shell after Z=82 and N=126 with the calculated Woods-Saxon single-particle levels.Then,the results of PES in ^(294)Og is illustrated from the(X,Y)scale to the(β_(2),γ)scale.Theγdegree of freedom reveals the shape evolution clearly during the fission process.The structure near the minimum and saddle point of the PES in the Z=118,119,120 nuclei is demonstrated simultaneously.Based on the potential energy curves,general trends of the evolution of the fission barrier heights and widths are also studied.The triaxial deformation in these superheavy mass regions plays a vital role in the first fission barrier,showing a significant reduction in both triaxial paths.In addition,the model-dependent fission barriers of proton-rich nuclei ^(295)Og,296119,and 297120 are analyzed briefly.Our studies could be valuable for synthesizing the superheavy new elements in the forthcoming HIAF and other facilities.

Study of the dinuclear system for^(296)119 superheavy compound nucleus in fusion reactions

This investigation aims to find an appropriate dinuclear system for the formation of^(296)119 superheavy compound nucleus.By studying the driving potential and measuring the capture cross section of the reactions,the evolution of the dinuclear system can be understood.In this study,we obtained capture,fusion,and evaporation residue cross sections and survival probability at energies near the Coulomb barrier for four reactions,namely ^(45)Sc+^(251)Cf,^(42)Ca+^(254)Es,^(39)K+^(297)Fm,and ^(38)Ar+^(258)Md.Our caleulations show that the reaction 38Ar+258 Md is a suitable choice for the formation of an element with 119 protons among the studied reactions from a the-oretical viewpoint.

Research on some superheavy nuclei

Studies on some superheavy nuclei are performed. The α decay energies are calculated by an improved local binding energy formula, and the α decay half-lives are calculated by the Viola-Seaborg formula. Good agreements between theoretical and experimental results are reached.

Alpha decay of heavy and super heavy nuclei with a generalized electrostatic potential

Half-lives ofαdecay for Z≥84 nuclei are calculated based on the WKB theory applied for a phenomenological potential barrier composed of a centrifugal contribution and a screened electrostatic interaction represented by a Hulthen potential.For favored decays,the model has a single adjustable parameter associated with the screening of the electrostatic potential.The description of half lives for unfavored decays requires an additional hindrance term.A good agreement with experimental data is obtained in all considered cases.The evolution of the screening parameter for each nucleus revealed its dependence on shell filling.The model is also used for theoretical predictions on a few nuclei with uncertain or incomplete decay information.

Angular momentum dependence of quasifission dynamics in the reaction ^(48)Ca+^(244)Pu

The quasifission dynamics in the reaction ^(48)Ca+^(244)Pu is investigated in the framework of time-dependent Hartree-Fock(TDHF)theory. The calculations are performed in three-dimensional Cartesian coordinate without any symmetry restrictions. The full Skyrme energy functional is incorporated in our TDHF implementation. The quasifission dynamics is quite sensitive to the angular momentum of colliding system. The contact time of quasifission decreases as a function of angular momentum and then forms a plateau with small oscillations. The quasifission process is accompanied by an important multi-nucleon transfer. The quantum shell effect plays a crucial role in the mass and charge of quasifission fragments. The mass-angle distribution of the fragments is calculated, which can be compared directly with future experiments.