The concept of heavy particle radioactivity (HPR) is changed to allow emitted particles with Z_e>28 from parents with Z>110 and daughter around 208Pb. Calculations for superheavy (SH) nuclei with Z=104-124 are showing a trend toward shorter half-lives and larger branching ratio relative to alpha decay for heavier SHs. It is possible to find regions in which HPR is stronger than alpha decay. The new mass table AME11 and the theoretical KTUY05 and FRDM95 masses are used to determine the released energy. For 124 we found isotopes with half-lives in the range of ns to ps.
We have constructed new proximity function particularly for interaction between two superheavy nuclei based on the experimental alpha decay half-lives. The new proximity function is used to produce the alpha decay half-lives of superheavy nuclei whose experimental values are known. The new proximity function produces the alpha decay half-lives close to the experiments. Hence we can conclude that the new proximity function can be used to study the interaction between two superheavy nuclei.
Alpha decay favoured isotopes of some superheavy nuclei: Spontaneous fission versus alpha decay
自发裂变和α衰变是超重核的主要衰变方式。与自发裂变半衰期相比，具有较小α衰变半衰期的超重核将在裂变中存活，并且可以通过α衰变在实验室中检测到。我们研究了Z = 100-130原子范围内的一些超重元素的α衰变半衰期和自发半衰期。超重核的自发裂变半衰期已经用唯象公式计算，α衰变半衰期用Viola-Seaborg-Sobiczewski公式（Sobiczewski et al. 1989）、Brown（1992）的半经验关系式和Dasgupta-Schubert and Reyes（2007）基于广义液滴模型的公式计算。结果报告于此。
We have investigated most stable superheavy nuclei by studying the decay properties such as alpha decay, cluster decay and spontaneous fission. We have investigated nine stable nuclei in the island of stability which can be detected through fission are 318123(10.5ms), 319123(4.68μs), 317124(1.74x104 y), 318124(2.70x101 y), 319124(2.83x10-2 y), 320124(1.91x10-5 y), 319125(2.46x109 y), 320125(3.81x106 y) and 321125(3.99x103 y). Present work also investigates three stable superheavy nuclei which can be detected through alpha decay which are 318125(1.03x1012 y), 319126(5.77x1011 y) and 320126(3.99…
This work investigated the first-chance survival probabilities of highly excited compound superheavy nuclei in the prospect of synthesizing new superheavy elements. The main feature of our modelings is the adoption of microscopic temperature dependent fission barriers in calculations of fission rates. A simple derivation is demonstrated to elucidate the connection between Bohr-Wheeler statistical model and imaginary free energy method, obtaining a new formula for fission rates. The best modeling is chosen with respect to reproducing the experimental fission probability of $^{210}$Po. Systemati…
Octupole deformed shapes in neutron-rich actinides and superheavy nuclei as well as extremely deformed shapes of the N~Z light nuclei have been investigated within the framework of covariant density functional theory. We confirmed the presence of new region of octupole deformation in neutron-rich actinides with the center around Z~96, N~196 but our calculations do not predict octupole deformation in the ground states of superheavy Z~108 nuclei. As exemplified by the study of 36Ar, the nodal structure of the wavefunction of occupied single-particle orbitals in extremely deformed structures allo…
The experimentally available data on the alpha decay half lives and Q? values for 96 superheavy nuclei are used to fix the parameters for a modified version of the Brown empirical formula through two fitting procedures which enables its comparison with similar fits using Viola-Seaborg and Royer formulas. The new expressions provide very good agreement with experimental data having fewer or the same number of parameters. All formulas with the obtained parameters are then extrapolated to generate half lives predictions for 125 unknown superheavy alpha emitters. The nuclei where the employed empi…
We present a selection of the first results obtained in a comprehensive calculation of ground state properties of even-even superheavy nuclei in the region of 96 < Z < 136 and 118 < N < 320 from the Quark-Meson-Coupling model (QMC). Ground state binding energies, the neutron and proton number dependence of quadrupole deformations and Q$_α$ values are reported for even-even nuclei with 100 < Z < 136 and compared with available experimental data and predictions of macro-microscopic models. Predictions of properties of nuclei, including Q$_α$ values, relevant for planning future experiments are p…
Half-lives of beta+ decay and electron capture are studied in some selected superheavy nuclei produced in hot fusion reactions, namely, 290Fl, 293Mc, 294Lv, and 295Ts. The nuclear structure is described microscopically from deformed self-consistent Skyrme Hartree-Fock mean-field calculations that include pairing correlations. The sensitivity of the half-lives to deformation and to the QEC energies, which are still not determined experimentally, are studied. The results are compared with phenomenological alpha-decay half-lives, showing that the latter decay mode is dominant in this mass region.
The competition between alpha- and beta+/EC-decay modes is studied systematically in nuclei along the alpha-decay chains following the synthesis of superheavy nuclei with Z = 119 and Z = 120. A microscopic approach based on deformed self-consistent Hartree-Fock mean-field calculations with Skyrme forces and pairing correlations is used to describe the beta+ and electron capture weak decays, whereas the alpha-decay is estimated from existing phenomenological expressions. It is shown that alpha-decay is in most cases the dominant decay mode, but interesting instances are identified where the hal…
The modes of decay for the even-even isotopes of superheavy nuclei of Z = 118 and 120 with neutron number $160 \leq N \leq 204$ are investigated in the framework of the axially deformed relativistic mean field model. The asymmetry parameter $η$ and the relative neutron-proton asymmetry of the surface to the center ($R_η$) are estimated from the ground state density distributions of the nucleus. We analyze the resulting asymmetry parameter $η$ and the relative neutron-proton asymmetry $R_η$ of the density play a crucial role in the mode(s) of decay and its half-life. Moreover, the excess neutro…
A statistical approach based on the Weisskopf evaporation theory has been developed to describe the de-excitation process of highly excited heavy and superheavy nuclei, in particular for the proton-rich nuclei. The excited nucleus is cooled by evaporating $γ$-ray, light particles (neutrons, protons, $α$ etc) in competition with the binary fission, in which the structure effects (shell correction, fission barrier, particle separation energy) contribute to the processes. The formation of residual nuclei is evaluated via sequential emission of possible particles above the separation energies. The…
The modes of decay for the even-even isotopes of superheavy nuclei of Z = 118 and 120 with neutron number $160 \leq N \leq 204$ are investigated in the framework of the axially deformed relativistic mean field model. The asymmetry parameter $η$ and the relative neutron-proton asymmetry of the surface to the center ($R_η$) are estimated for the ground state density distributions of the nuclei. We suggest that the resulting asymmetry parameter $η$ and the relative neutron-proton asymmetry $R_η$ of the density play a crucial role in the preformation factor of the decay half life.
The microscopic approach of fission rates and neutron emission rates in compound nuclei have been applied to $^{258}$No and $^{286}$Cn. The microscopic framework is based on the finite-temperature Skyrme-Hartree-Fock+BCS calculations, in which the fission barriers and mass parameters are self-consistently temperature dependent. The fission rates from low to high temperatures can be obtained based on the imaginary free energy method. The neutron emission rates are obtained with neutron gases at surfaces. Finally the survival probabilities of superheavy nuclei can be calculated microscopically. …
Fission-fragment mass and total-kinetic-energy (TKE) distributions following fission of even-even nuclides in the region $74 \leq Z \leq 126$ and $92 \leq N \leq 230$, comprising 896 nuclides have been calculated using the Brownian shape-motion method. The emphasis is the region of superheavy nuclei. To show compatibility with earlier results the calculations are extended to include earlier studied regions. An island of asymmetric fission is obtained in the superheavy region, $106\leq Z\leq114$ and $162\leq N\leq 176$, where the heavy fragment is found to be close to $^{208}$Pb and the light f…
Using the Hartree-Fock-Bogoliubov (HFB) self-consistent mean-field theory with the SkM* Skyrme energy-density functional, we study nuclear structure properties of even-even superheavy nuclei (SHN) of $Z=120$ isotopes and $N=184$ isotones. The shape of the nucleus along the lowest energy curve as a function of the quadrupole moment $Q_{20}$ makes a sudden transition from the oblate spheroids (biconcave discs) to the toroidal shapes, in the region of large oblate quadrupole moments.
