Half-lives Of Superheavy Nuclei Research Articles

Random forest-based prediction of decay modes and half-lives of superheavy nuclei

Random forest-based prediction of decay modes and half-lives of superheavy nuclei

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

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.

Diffuseness parameter as a bottleneck for accurate half-life calculations

An investigation of the calculated $\alpha$ decay half-lives of super heavy nuclei (SHN) reveals that the diffuseness parameter is a great bottleneck for achieving accurate results and predictions. In particular, when universal proximity function is adopted for nuclear potential, half-life is found to vary significantly and nonlinearly as a function of diffuseness parameter. To overcome this limiting hurdle, a new semiempirical formula for diffuseness that is dependent on charge and neutron numbers is proposed in this work. With the model at hand, half-lives of 218 SHN are computed, for 68 of which there exists available experimental data and 150 of which are predicted. The calculations of half-lives for 68 SHN are compared against experimental data and the calculated data obtained by using deformed Woods-Saxon, deformed Coulomb potentials model, and six semiempirical formulas. The predictions of 150 SHN are compared against the predictions of seven of the current best semiempirical formulas. Calculations of the present study are in good agreement with the experimental half-lives outperforming all but ImSahu semiempirical formula. Moreover, the predictions of our model are consistent with predictions of the semiempirical formulas. We strongly conclude that more attention should be directed toward obtaining accurate diffuseness parameter values for using it in nuclear calculations.

Predictions on the alpha decay half lives of superheavy nuclei with Z = 113 in the range 255 ≤ A ≤ 314

An intense study of the alpha decay properties of the isotopes on superheavy element with Z=113 has been performed within the Coulomb and proximity potential model for deformed nuclei (CPPMDN) within the wide range 255≤A≤314. The predicted alpha decay half lives of 278113 and 282113 and the alpha half lives of their decay products are in good agreement with the experimental data. 6α chains and 4α chains predicted respectively for 278113 and 282113 are in agreement with the experimental observation. Our study shows that the isotopes in the mass range 278≤A≤286 will survive fission and can be synthesized and detected in the laboratory via alpha decay. In our study, we have predicted 6α chains from 279113, 4α chains from 286113, 3α chains from 280,281,283113, 2α chains from 284113 and 1α chain from 285113. We hope that these predictions will be a guideline for future experimental investigations.

Alpha-decay and spontaneous fission half-lives of super-heavy nuclei around the doubly magic nucleus270Hs

The α-decay and spontaneous fission half-lives of nuclei around 270 Hs are calculated with formulas derived from an in-depth analysis of the available experimental data and of results of theoretical models. The parameters of these formulas result from the fit of half-lives with respect to the reaction energies, the height of the SF barrier and the fissionability. The calculated partial and total half-lives are compared with the experimental data and results of other approximations. Half-life predictions are made for many unknown nuclei.

COMPETITION OF α DECAY AND HEAVY PARTICLE DECAY IN SUPERHEAVY NUCLEI

Calculations of half-lives of superheavy nuclei (SH) show an unexpected result: For some of them heavy particle radioactivity (HPR) dominates over α decay (branching ratios larger than 1). The new mass table AME11 and the theoretical KTUY05 and FRDM95 masses are used to determine Q-values. For Z = 124 we found isotopes with half-lives in the range of ns to ps.

SPONTANEOUS FISSION HALF-LIVES IN VARIOUS MACROSCOPIC-MICROSCOPIC MODELS

The problem of describing spontaneous fission for the entire region of superheavy nuclei is continually present in theoretical investigations. This study outlines the results of the calculations of fission barriers and spontaneous fission half-lives for superheavy nuclei in the region of Z =100-122 using a mean field model. We examine four distinct macroscopic models and two types of pairing interactions. Our approach is based on the deformed Woods-Saxon potential. Spontaneous fission half-lives are calculated using a multi-dimensional dynamical-programming method, where the action integral is minimized within a three dimensional deformation space (β2, β4, β6).

Systematic studies on α-decay half-lives for super heavy nuclei

Radioactive decay of super heavy nuclei via the emission of α-particles has been studied theoretically in the preformed cluster model (PCM). The nucleus-nucleus (NN) potential is obtained by double folding the density distributions of the α-particle and the daughter nucleus with a realistic effective interaction. The M3Y effective interaction, supplemented by a zero-range pseudo-potential for exchange term, is used to calculate the NN potential. The α decay half-lives for 317 nuclei at Z = 102–120 are performed in the PCM framework with the theoretical Q values extracted from the Möller-Nix-Kratz and Liran-Marinov-Zeldes mass tables and are compared with the experimental data. The calculated results are also compared with those obtained by using Q values from the Muntian-Hofmann-Patyk-Sobiczewski and Myers–Swiatecki mass estimates.

Half-Lives of Superheavy Nuclei in Z = 113 Alpha Decay Chain

The generalized liquid drop model (GLDM), including the proximity effects and centrifugal potential, and the cluster model with Cosh potential are used to study the half-lives of some Z = 113 isotopes and their α-decay products. The experimental half-lives of 284113, 283113, 282113 and their α-decay products are well reproduced by the two models when zero angular momenta transfer is assumed. For 278113 and its α-decay products, both the GLDM and the cluster model could provide satisfactory results if we assume the α particle carry five units of angular momenta, which indicates that possible nonzero angular momenta transfer and need further experimental measurements with high precision. Finally, we show that half-lives of α-decay are quite sensitive to the angular momentum transfers, and a formula could be used to describe the correlation between α-decay half-life and angular momentum transfer successfully.

Ground State Properties of Superheavy Nuclei in Macroscopic-Microscopic Model

The ground state properties of superheavy nuclei are systematically calculated by the macroscopic-microscopic (MM) model with the Nilsson potential. The calculations well produced the ground state binding energies, α-decay energies, and half lives of superheavy nuclei. The calculated results are systematically compared with available experimental data. The calculated results are also compared with theoretical results from other MM models and from relativistic mean-field model. The calculations and comparisons show that the MM model is reliable in superheavy region and that the MM model results are not very sensitive to the choice of microscopic single-particle potential.

PAIRING AND α-DECAY

Nuclear pairing interaction plays a crucial role in both macroscopic-microscopic and fully macroscopic descriptions of nuclei. In the present study we discuss different pairing interactions (monopole and δ pairing forces) and the methods allowing for the particle number symmetry restoration in addition to the customary BCS treatment of pairing correlations in the context of α-decay half-lives for superheavy nuclei. The calculations are done in the macroscopic-microscopic framework for even-even nuclei with Z > 110.

PROPERTIES OF SUPERHEAVY NUCLEI IN VARIOUS MACROSCOPIC-MICROSCOPIC MODELS

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}.