Alpha-decay Half-lives Research Articles

Theoretical approaches on the α-decay of spherical Bismuth isotopes

In this paper, the alpha decay process is investigated through the theoretical approaches for spherical Bismuth (Bi) isotopes in the range 187 [Formula: see text] A [Formula: see text] 214. The results are compared with the experimental data for isotopes of Bi with the modified Coulomb and proximity potential model (MCPPM). We analyze the systematics of alpha decay half-life (HL) of Bi isotopes versus the decay energy and the total [Formula: see text]-kinetic energy. The results and their systematics are compared with the available experimental data and with those data obtained from empirical models as the Viola-Seaborg (VS) formula, Royer (R) and the two versions of modified Brown (mB) empirical formulas. The computed half-lives (HLs) are compared with the experimental data and also with the existing empirical estimates and are found in good agreement.

Systematic study of α-decay half-lives using Royer and related formula

The alpha decay half-lives of 356 isotopes were studied using the Royer and related Formula and are compared with experimental data. The study shows that the predicted half-lives match well with experimental data over a wide range for each (Z,N) parity of the parent nuclei. We have calculated the standard deviation of log10⁡Tα(s), for each formula and our study indicate that, for alpha decay studies, generally, analytical ℓ-dependent formula proposed by Royer, with σRB=0.4373, is the best model followed by the formula proposed by Denisov and Khudenko (DK), σDK=0.4743 for all 356 nuclei. We hope the present study is a clear indicator of the predictive power of Royer and related formula.

α -decay half-lives of superheavy nuclei

The alpha-decay half-lives of superheavy nuclei (SHN) with Z >= 104 are investigated by employing the effective liquid drop model (ELDM). By comparison between the calculated half-lives and the ...

Predictions on the modes of decay of odd [formula omitted] superheavy isotopes within the range [formula omitted

The decay modes of 1051 odd Z superheavy nuclei within the range 105 ≤Z≤ 135, and their daughter nuclei are studied by comparing the alpha decay half-lives with the spontaneous fission half-lives. The alpha decay half-lives are calculated using the Coulomb and proximity potential model for deformed nuclei (CPPMDN) proposed by Santhosh et al. (2011) and the spontaneous fission half-lives are obtained with the shell-effect dependent formula of Santhosh et al. (Santhosh and Nithya, 2016). For a theoretical comparison, the alpha decay half-lives are also computed with the Coulomb and proximity potential model (CPPM), Viola–Seaborg–Sobiczewski semi-empirical relation (VSS), Universal curve of Poenaru et al. (UNIV), the analytical formula of Royer, and the Universal decay law of Qi et al. (UDL). The predicted decay modes and half-lives were compared with the available experimental results. The proton and neutron separation energies are calculated to identify those nuclei, which decay through proton and neutron emission. From the entire study of odd Z superheavy elements, it is seen that among 1051 nuclei, 233 nuclei exhibit proton emission and 18 nuclei exhibit neutron emission. 56 nuclei are stable against alpha decay with negative Q value for the decay. 92 nuclei show alpha decay followed by spontaneous fission and 9 nuclei show alpha decay followed by proton emission. 39 nuclei decay through full alpha chain and 595 nuclei decay through spontaneous fission. We hope that the study will be very useful for the future experimental investigations in this field.

Alpha-decay half-lives for isotopes of even-even nuclei: A temperature-dependent approach with Woods-Saxon potential

The alpha-decay process is investigated in the presence of the nuclear temperature. Using an analytical approach for the calculation of effective sharp radius and a new barrier potential, the half-lives for the even-even nuclei of Po, Pb, Ra, Rb, Rn, Th and U are derived and compared with the experimental data.

A comparative analysis of alpha-decay half-lives for even–even 178Pb to 234U isotopes

The feasibility for the alpha decay from the even–even transitions of 178Pb to 234U isotopes has been studied within the Coulomb and proximity potential model (CPPM). The alpha decay half-lives are considered from different theoretical approaches using Semi-empirical formula of Poenaru et al. (SemFIS), the Universal Decay law (UDL) of Qi et al., Akrawy–Dorin formula of Akrawy and Poenaru (ADF), the Scaling law of Brown (SLB) and the Scaling Law of Horoi et al. (SLH). The numerical results obtained by the CPPM and compared with other method as well the experimental data.

Alpha decay studies on Po isotopes using different versions of nuclear potentials

The alpha decays from 186-224Po isotopes have been studied using 25 different versions of nuclear potentials so as to select a suitable nuclear potential for alpha decay studies. The computed standard deviation of the calculated half-lives in comparison with the experimental data suggested that proximity 2003-I is the apt form of nuclear potential for alpha decay studies as it possesses the least standard deviation, $ \sigma =0.620$ . Among the different proximity potentials, proximity 1966 ( $ \sigma =0.630$ and proximity 1977 ( $ \sigma =0.636$ , are also found to work well in alpha decay studies with low deviation. Among other versions of nuclear potentials (other than proximity potentials), Bass 1980 is suggested to be a significant form of nuclear potential because of its good predictive power. However, while the other forms of potentials are able to reproduce the experimental data to some extent, these potentials cannot be considered as apposite potentials for alpha decay studies in their present form. Since the experimental correlation of the models is noticed to be satisfying, the alpha decay half-lives of certain Po isotopes that are not detected experimentally yet have been predicted.

Estimation of the alpha decay of Platinum isotopes using different versions of theoretical formula

The alpha decay half-lives of even–even and even–odd Platinum (Pt) nuclei have been studied within the Coulomb and proximity potential model (CPPM). The present study is restricted to even–even nuclei with [Formula: see text]–198. The results are compared with other calculations such as the Semi-empirical formula (SemFIS) from Poenaru et al. based on fission theory of alpha decay, the Viola–Seaborg (VS), Royer (R) and Brown formulae. Also, the alpha decay half-lives have been calculated using the Scaling law of Brown (SLB), the Universal Decay Law (UDL) of Qi et al., the Scaling Law of Horoi et al. (SLH), and Akrawy–Dorin formula (ADF) of Akrawy and Poenaru, which are the Royer modified formula for alpha decay half-live by adding asymmetry term.

Decay properties of 256-339Ds superheavy nuclei

The decay properties of 84 isotopes of darmstadtium superheavy nuclei (Z = 110) have been studied using various theoretical models. The proton emission half-lives, the alpha decay half-lives, the spontaneous fission half-lives and the cluster decay half-lives of all the isotopes are evaluated. The one-proton emission half-lives and the alpha decay half-lives are predicted using the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The calculated alpha half-lives are compared with the available experimental results as well as with the predictions of other theoretical models. The predicted half-lives matches well with the experimental results. The one-proton half-lives are also compared with the predictions using other formalisms. The shell-effect-dependent formula of Santhosh et al. has been employed for calculating the spontaneous fission half-lives. A theoretical comparison of spontaneous fission half-lives with four different formalisms is performed. By comparing the one-proton emission half-lives, the alpha decay half-lives and the spontaneous fission half-lives decay modes are predicted for all the isotopes of Ds. It is seen that the isotopes within the range $ 256 \le A \le 263$ and $ 279 \le A \le 339$ decay through spontaneous fission and the isotopes $ 264 \le A \le 278$ exhibit alpha decay. Cluster decay half-lives are calculated using different models including the Coulomb and proximity potential (CPPM), for determining the magicities in the superheavy region. The effect of magicity at N = 184 and N = 202 were confirmed from the plot of $ \log_{10}T_{1/2}$ versus neutron number of the daughter nuclei for the emission of different clusters. We hope that the systematic and detailed study of all the possible decay modes of 256-339Ds using various theoretical models will be helpful in the experimental identification of the isotopes of the element in the future.

Microscopic description of the competition between spontaneous fission and α-decay in neutron-rich Ra, U and Pu nuclei

Constrained mean-field calculations, based on the Gogny-D1M energy density functional, have been carried out to describe fission in Ra, U and Pu nuclei with neutron number 144 ≤ N ≤ 176. Fission paths, collective masses and zero-point quantum vibrational and rotational corrections are used to compute the spontaneous fission half-lives. We also pay attention to isomeric states along the considered fission paths. Alpha decay half-lives have also been computed using a parametrization of the Viola-Seaborg formula. Though there exists a strong variance of the predicted fission rates with respect to the details involved in their computation a robust trend is obtained indicating, that with increasing neutron number fission dominates over α-decay. Our results also suggest that a dynamical treatment of pairing correlations is required within the microscopic studies of the fission process in heavy nuclear systems.

Theoretical approaches to alpha decay half-lives of super-heavy nuclei

We consider the systematics of α-decay half-lives of super-heavy nuclei versus the decay energy and the total α-kinetic energy. We calculate the half-lives using the experimental Qα values. The computed half-lives are compared with the experimental data and with existing empirical estimates and are found to be in good agreement. Also, we obtain α-preformation factors from the ratio between theoretical and experimental results for some super-heavy nuclei and evaluate the standard deviation. The results indicate the acceptability of the approach.

Predictions on the modes of decay of even [formula omitted] superheavy isotopes within the range [formula omitted

The decay modes and half lives of all the even Z isotopes of superheavy elements within the range 104≤Z≤136 have been predicted by comparing the alpha decay half-lives with the spontaneous fission half-lives. The Coulomb and proximity potential model for deformed nuclei (CPPMDN) and the shell-effect-dependent formula of Santhosh et al. are used to calculate the alpha half-lives and spontaneous fission half-lives respectively. For theoretical comparison the alpha decay half-lives are also calculated using Coulomb and proximity potential model (CPPM), the Viola–Seaborg–Sobiczewski semi-empirical (VSS) relation, the universal (UNIV) curve of Poenaru et al., the analytical formula of Royer and the universal decay law (UDL) of Qi et al. Another tool used for the evaluation of spontaneous fission half-lives is the semi-empirical formula of Xu et al. The nuclei with alpha decay half-lives less than spontaneous fission half-lives will survive fission and hence decay through alpha emission. The predicted half lives and decay modes are compared with the available experimental results. The one-proton and two-proton separation energies of all the isotopes are calculated to find nuclei which lie beyond the proton drip line. Among 1119 even Z nuclei within the range 104≤Z≤136, 164 nuclei show sequential alpha emission followed by subsequent spontaneous fission. Since the isotopes decay through alpha decay chain and the half-lives are in measurable range, these isotopes are predicted to be synthesized and detected in laboratory via alpha decay. 2 nuclei will decay by alpha decay followed by proton emission, 54 nuclei show full alpha chains, 642 nuclei will decay through spontaneous fission, 166 nuclei exhibit proton decay and 91 isotopes are found to be stable against alpha decay. All the isotopes are tabulated according to their decay modes. The study is intended to enhance further experimental investigations in superheavy region.

Correlation between alpha preformation probability, decay half-life and barrier assault frequency

Calculation of alpha particle preformation probabilities for some alpha emitters is considered in the framework of a recent proposed barrier penetration formula, by two different approximations. The behavior of alpha particle preformation probability with the variation of neutron and proton numbers of parent nuclei for isotopes, in the range [Formula: see text], and isotones, in the range [Formula: see text], is investigated. The same correlations are then studied for the alpha decay half-life, the barrier assault frequency, barrier height and barrier penetration probability. Strong correlations are found and in a good agreement with experimental expectations.

Influence of deformed surface diffuseness on alpha decay half-lives of actinides and lanthanides

By using semiclassical WKB method and taking into account the Bohr–Sommerfeld quantization condition, the alpha decay half-lives of some deformed lanthanide (with 151≤A≤160 and 66≤Z≤73) and rare-earth nuclei (with 217≤A≤261 and 92≤Z≤104) have been calculated. The effective potential has been considered as sum of deformed Woods–Saxon nuclear potential, deformed Coulomb potential, and centrifugal potential. The influence of deformed surface diffuseness on the potential barrier, transmission coefficient at each angle, assault frequency, and alpha decay half-lives has been investigated. Good agreement between calculated half-lives with deformed surface diffuseness and experiment is observed. Relative differences between calculated half-lives with deformed surface diffuseness and with constant surface diffuseness were significant.

Alpha decay half-lives for heavy and super-heavy isotopes

We considered the systematics of Alpha-decay (AD) half-life (HL) of super-heavy nuclei (SHN) versus the decay energy and the total [Formula: see text]-kinetic energy. We have considered a potential model with Yukawa proximity potential and thereby calculated the HLs. Our results compared with experimental data and the empirical estimates. Also, we obtained [Formula: see text]-preformation factors from the ratio between theoretical and experimental results for a few super heavy nuclei. The results indicate the acceptability of the approach.

Theoretical predictions for the decay chain of the nuclei Og293,295–297

The alpha-decay half-lives of recently synthesized superheavy nuclei (SHN) are investigated by employing a generalized liquid drop model (GLDM) and Royer's analytical formula. The excellent agreement with the experimental data indicates the GLDM and the analytical formula are useful tools to investigate alpha-decay half-lives.The competition between alpha decay and spontaneous fission is analyzed in detail and alpha-decay half-lives and decay modes are predicted for the unknown nuclei (293,295-297)Og.

α-Decay Half-Lives for Pb Isotopes Within Gamow-Like Model

We studed alpha decay half-lives of Pb isotopes in the range 178 ≤ A ≥ 220, whithin Gamow-like model (GLM) which is based on Gamow theory. The empirical formulae like Royer formula, Universal Decay Low (UDL), Viola-Seaborg formula (VSS), Semi-empirical formula for Poenaru (SemFIS) and Denisov & Khudenko formula (DEKH) are used to calculate alpha decay half-lives. The results are compared with experimental data, and also with other theoretical models, the results are in a good agreement was achieved with experimental data.

Optimal temperature for alpha-decay half-lives with Yukawa proximity potential

The paper investigates the alpha-decay half-lives of some nuclei by modifying the Coulomb potential with Yukawa proximity potential for the excited state decays. A new relation is found for the width diffuseness of the nuclear surface [Formula: see text] and the sharp radii [Formula: see text] for the excited system. The parameters are fitted to the experimental data for the nuclear temperature in the range [Formula: see text] (MeV). A comparison of half-life indicates that the probability of decay increases with increasing nuclear temperature for the excited system. The comparison of the results with the existing experimental data is motivating.

Theoretical prediction of probable isotopes of superheavy nuclei of Z = 122

We have studied the [Formula: see text]-decay half-life and spontaneous fission half-lives of isotopes of superheavy element [Formula: see text] in the range [Formula: see text]. A comparison of calculated alpha half-lives with the literature [D. N. Poenaru, R. A. Gherghescu and W. Greiner, Phys. Rev. C 83 (2011) 014601, D. N. Poenaru, R. A. Gherghescu and W. Greiner, Phys. Rev. C 85 (2012) 034615] and the analytical formulas of Royer [G. Royer, J. Phys. G; Nucl. Part. Phys. 26 (2000) 1149] shows good agreement with each other. To identify the mode of decay of these isotopes, the spontaneous-fission half-lives were also evaluated using the semiempirical relation given by [C. Xu, Z. Ren and Y. Guo, Phys. Rev. C 78 (2008) 044329]. A comparative study on the competition of alpha decay versus spontaneous fission of superheavy nuclei (SHN) reveals that around eight isotopes ([Formula: see text]122) survive fission and have alpha decay channel as the prominent mode of decay and hold the possibility to be synthesized in the laboratory. The alpha decay half-lives and spontaneous fission half-lives of SHN with [Formula: see text], [Formula: see text]–306, with [Formula: see text], [Formula: see text]–300, and with [Formula: see text], [Formula: see text]–297 are also studied. The present study will be useful in the synthesis of superheavy elements [Formula: see text] by using the actinide based reactions with stable projectiles heavier than [Formula: see text]Ca.

Predictions on the alpha decay chains of superheavy nuclei with Z = 121 within the range 290 ≤ A ≤ 339

A systematic study on the alpha decay half-lives of various isotopes of superheavy element (SHE) [Formula: see text] within the range [Formula: see text] is presented for the first time using Coulomb and proximity potential model for deformed nuclei (CPPMDN). The calculated [Formula: see text] decay half-lives of the isotopes within our formalism match well with the values computed using Viola–Seaborg systematic, Universal curve of Poenaru et al., and the analytical formula of Royer. In our study by comparing the [Formula: see text] decay half-lives with the spontaneous fission half-lives, we have predicted [Formula: see text] chain from [Formula: see text]121, [Formula: see text] chain from [Formula: see text]121 and [Formula: see text] chain from [Formula: see text]121. Clearly our study shows that the isotopes of SHE [Formula: see text] within the mass range [Formula: see text] will survive fission and can be synthesized and detected in the laboratory via alpha decay. We hope that our predictions will provide a new guide to future experiments.