Alpha-decay Half-lives Research Articles

Calculation of α-decay half-lives of 186−218Po isotopes and actinide nuclei using a new phenomenological potential

This paper is devoted to the calculations of alpha decay half-lives of [Formula: see text]Po [Formula: see text] isotopes and actinide nuclei between the atomic numbers Z = 90 and Z = 102, using an energy-dependent potential model. The [Formula: see text]-nucleus effective potential employed in this study includes a Coulomb potential, a centrifugal barrier potential, and a nuclear potential. The nuclear potential is chosen to be the energy-dependent singularized harmonic potential, typical of nuclear interactions. The role of the energy-dependent potential is very significant in this study. Indeed, when compared to the experimental data, our results are found to be improved when energy-dependent interaction potential is employed compared to when energy-independent interactions are used, especially for small values of the parameter [Formula: see text] as evidenced by the values of the root mean square deviation.

An alpha decay study of superheavy nuclei within a Coulomb and proximity potential model including a Q-value dependent surface diffuseness parameter

Using the Coulomb and Proximity Potential Model (CPPM) and a Q-value dependent surface diffuseness parameter in the proximity potential, the alpha decay half-lives of 75 experimentally synthesized superheavy nuclei were determined. Comparisons are made between the obtained results and experimentally determined alpha decay half-lives, as well as the predictions of Yang et al.’s recent study [Nucl. Phys. A 1014 (2021) 122250], which is based on the Unified Fission Model (UFM) with a new preformation parameter. The lowest standard deviation of 0.621 is obtained for CPPM calculations with Q-value-dependent surface diffuseness parameter. The calculation is extended further to estimate the alpha decay half-lives [Formula: see text]119 and [Formula: see text]120 superheavy isotopes and compared with the predictions of UFM. Finally, the results of the calculations are compared to the predictions of the UDL formula [Phys. Rev. Lett. 103 (2009) 072501] and the modified Hutsukawa formula [Nucl. Part. Phys. Proc. 339 (2023) 92].

Alpha-decay half-lives and alpha-capture cross-sections

The same alpha-nucleus interaction describes the alpha-decay and alpha-capture reactions in the Unified Model for Alpha-Decay and Alpha-Capture (UMADAC). The data for the ground-state-to-ground-state alpha-transition half-lives in 420 nuclei, the half-lives for alpha-transition from the ground state to the first excited 2+ state in 74 even–even nuclei, and the alpha-capture cross sections of 20 spherical and deformed nuclei are used for defining the parameters of the UMADAC. The pointed data are well described in the framework of the UMADAC utilizing the obtained parameters. The ground-state-to-ground-state alpha-transition half-lives in 3802 nuclei with the proton Z and nucleon A numbers in the ranges 50 ≤Z≤ 126 and 97 ≤A≤ 340 are calculated in the UMADAC and presented in the Table 1. The quadrupole and hexadecapole deformations of the daughter nucleus are considered in the UMADAC. The minimal values of the orbital momenta of the alpha-transition between the ground states are found using available experimental and theoretical data for the ground state spin and parity values of nuclei. The half-lives for 223 alpha-transitions from the ground-state of the parent even–even nuclei to the lowest 2+ state of the daughter nuclei with the proton Z and nucleon A numbers in the ranges 52 ≤Z≤ 102 and 108 ≤A≤ 254 are obtained in the UMADAC and given in the Table 2.

Evaluating the influence of unpaired nucleon on alpha clusterization in heavy Nuclei with N at 126

The determination of preformation factor was successively done for 343 nuclei: 212Po, 105 even-even, 85 odd-even, 78 even-odd and 75 odd-odd nuclei using the representation of clusterization states (RCS) and cluster-formation model (CFM) (Saleh Ahmed, 2017). As CFM well described the alpha clustering of the ground states of the nuclei, it was considered as bases of describing the effect of the last unpaired nucleon. The typical nucleus 212Po and the nuclei 213Po, 213At and 214At, or Po isoalpha group, which have the same alpha cluster were chosen to evaluate the hindrance of alpha clustering by their last unpaired nucleons. The hindrance was expressed in an initiated factor, named “alpha clustering hindrance factor”. The results agreed with others that have preformation factor using different methods and used to reproduce more accurate alpha decay half lives using Viola-Seaborg semiempirical formula for odd-even Po isotopes The alpha-formation hindrance factor showed an interesting behaviour that plays an important role in the provision of more information about the nuclear structure.

Prediction on the alpha decay half-lives of 223−243Am isotopes

Prediction on the alpha decay half-lives of 223−243Am isotopes

Alpha Decay Half-lives of Heavy and Superheavy Nuclei within a Deformed Double Folding Model

Alpha Decay Half-lives of Heavy and Superheavy Nuclei within a Deformed Double Folding Model

A Systematic study on the alpha decay of superheavy nuclei using empirical diffuseness parameter in the coulomb and proximity potential model

Recent studies of Dehghani et al [Mod. Phys. Lett. A 33 14 1850080 (2018)] and Abdul-latif et al [Phys. Rev. C 100, 024601 (2019)] revealed the importance of the diffuseness parameter in the calculation of alpha decay half-lives from superheavy elements using proximity potentials. In the present paper, predictions of the empirical formula for the diffuseness parameter proposed by Abdul-latif et al is analyzed in view of the diffuseness parameter calculated by Dehghani et al using WKB method and considering deformed Woods–Saxon nuclear potential, deformed Coulomb potential, and centrifugal potential; and related theoretical aspects. From the conclusions, we propose three new empirical formulae for the diffuseness parameter. Using the diffuseness parameter calculated from the proposed empirical formula in the Coulomb and Proximity Potential Model (CPPM), the alpha decay half-life of 68 superheavy nuclei is calculated and compared with the experimental values. The inclusion of the diffuseness parameter in proximity potential improved the predictive power of the CPPM considerably.

Study on the decay of Z = 127 – 132 superheavy nuclei via emission of 1-n and 2-n halo nuclei

The barrier penetrability, decay constant and decay half-life of 1-n halo nuclei 11Be, 15,17,19C, 22N, 23O, 24,26F, 29,31Ne, 34,37Na, 35,37Mg, and 55Ca; and 2-n halo nuclei 22C, 27,29F, 34Ne, 36Na, and 46P from Z = 127 – 132 parents were calculated within the framework of the Coulomb and proximity potential model by calculating the Q-values using the finite-range droplet model. A comparison between the decay half-lives is made by considering the halo candidates as a normal cluster and as a deformed structure with a rms radius. Neutron shell closure at 190, 196, 198, 200, 204, and 208 are identified from the plot of decay half-lives versus the neutron number of daughter nuclei (NP). The calculation of alpha decay half-life and spontaneous decay half-life showed that the majority of the parent nuclei survive spontaneous fission and decay through alpha emission. The Geiger-Nuttall plots of log10T1/2 versus Q-1/2 and universal plots of log10T1/2 versus -lnP for the emission of all 1-n and 2-n halo nuclei from the parents considered here are linear and show the validity of Geiger - Nuttall law in the case of decay of halo nuclei from superheavy elements.

Impact of nuclear rotation corrections on alpha decay half-lives of superheavy nuclei within 98 ≤ Z ≤ 120

The influence of nuclear rotation on the decay half-lives of superheavy nuclei within the range 98≤Z≤120 is investigated using the axially deformed relativistic Hartree-Bogoliubov theory in the continuum (DRHBc) with the PC-PK1 parameter set. The deduced DRHBc decay energies (with and without the rotation effect) are compared with those calculated from the macroscopic-microscopic WS4 and the available experimental binding energies. Six semi-empirical formulae, such as the Viola-Seaborg formula (VSS), the modified Brown formula (mB1), the semi-empirical relationship based on fission theory (SemFIS2), the Royer formula (R), the Wang formula (Wang) and the modified YQZR formula (MYQZR) are employed to estimate the half-lives of α decay. Among these formulae, the half-live predictions of SemFIS2 are found to gradually deviate from the systematic trend beyond Nd=184, showing that the probability of undergoing spontaneous fission is less feasible beyond this point. A minimum is observed at Nd=184, reflecting its neutron shell closure for the mass region considered on the nuclear chart. The results further indicate that, for 98≤Z≤104, the predictions of all semi-empirical formulae are more closely matched to the available experimental data when the rotation effect is taken into account. However, we have demonstrated that the effect of nuclear rotation gradually reduces as the atomic nucleus becomes heavier.

A systematic study of alpha decay half-lives of isotones in superheavy region

A systematic study of alpha decay half-lives of isotones in superheavy region

Improved calculation of alpha decay half-life by incorporating nuclei deformation shape and proximity potential

Accurate evaluation of alpha decay half-life is essential for understanding nuclear stability, ensuring nuclear safety, optimizing medical treatments, and studying astrophysical processes. Considering the deformed shape of nuclei, we calculated the alpha-decay half-life of 359 nuclei using the proximity potential. In addition, we employed the Wentzel–Kramers–Brillouin approximation to compute the penetration probability through the potential barrier comprising nuclear, Coulomb, and centrifugal potentials. Our calculations revealed that the penetration probability, and hence the alpha-decay half-life, depend on the direction of alpha particle emission relative to the axial symmetry of the nucleus. Furthermore, our results suggested that the dependence of alpha-decay on parent nuclei temperature needs to be reassessed. We tabulated the alpha-decay half-life for various nuclei, and our results showed better agreement with experimental data compared to theoretical data in the literature.

Comparison of different nuclear potentials to predict the alpha decay half-lives

Comparison of different nuclear potentials to predict the alpha decay half-lives

Theoretical predictions on the decay modes of 282−310Og

Possible decay modes of 282−310Og are studied within the framework of the Coulomb and Proximity Potential Model (CPPM), Universal Decay Law (UDL) and the Hatsukawa formula. A new diffusion parameter and a new preformation factor are included in the CPPM Model calculations. We have refitted the Hatsukawa formula to calculate the alpha and cluster decay half-lives in the superheavy region. The spontaneous fission (SF) half-lives are calculated using the shell correction energy-dependent formula of Santhosh et al. The predicted alpha decay half-lives are compared with the predictions of the UDL formula; and the predictions of Soumya et al. and Koyuncu et al. Possible heavy cluster decays from 284−297Og are also studied within the UDL formula and by using the empirical formula of Hatsukawa et al. with new fitting parameters, and a comparison is made with the predictions of Santhosh et al.

Systematic investigation of the alpha and cluster decay half-lives for heavy and superheavy nuclei within the shifted Deng-Fan potential

The half-lives of alpha decays for even-even nuclei with Z=60−118 and the cluster radioactivities for even-even emitters for which the experimental data are available, also the various cluster decays of even-even radium isotopes are calculated. Our calculations are within the framework of Wentzel-Kramers-Brillouin (WKB) method by considering the Bohr-Sommerfeld quantization condition based on the shifted Deng-Fan potential. The obtained results are compared with the squared Woods-Saxon and Cosh potentials and several theoretical models, including the universal model (UNIV), the unified fission model (UFM), the universal decay law (UDL), and Ni, Royer, Tavares and Balasubramaniam semiempirical formulas, as well as the experimental data. Good agreement between the experimental and the proposed potential model results, indicates that the shifted Deng-Fan potential is a suitable phenomenological potential to describe both alpha and cluster decays of radioactive nuclei. Also we observe the significant role of neutron magicity in the half-lives of cluster decays of radium isotopes at N=126 of daughter nuclei and the parent nucleus 214Ra.

Alpha decay and cluster radioactivity investigation of actinide nuclei

Based on the Unified Fission Model with a Woods–Saxon potential (UFMWS), we have investigated alpha decay and cluster radioactivity of actinide nuclei. To ensure accuracy, we determined the most precise [Formula: see text]-values by comparing the results of four nuclear mass models: the liquid drop model (LDM), the DZ28 model, the WS4 model, and the finite range droplet model (FRDM), which were recently improved using a machine learning algorithm. Among these models, it is found that the improved WS4 (IWS4) provides the most accurate [Formula: see text]-values, enabling the UFMWS model to effectively reproduce experimental alpha and cluster decay half-lives. Consequently, the UFMWS model using IWS4 [Formula: see text]-values was employed to explore various combinations of parent nuclei and alpha particle as well as even–even emitted clusters ranging from Be to Si. The obtained results are consistent with previous study that identified minima in half-lives near corresponding to the doubly magic [Formula: see text]Pb daughter nucleus or its neighboring nuclei. It is found that neutron-deficient parent nuclei generally displayed the shortest half-lives, most of which are within the experimental range. Considering the experimental limitations, cluster decays favorable for measurement in the actinide region were identified. Interestingly, these decays did not involve the most neutron-deficient nuclei.

Study of various ground state decay mechanisms of Actinide nuclei* *Financial support from the Department of Science and Technology (DST), New Delhi, India in the form of a research project grant (CRG/2021/001144) is gratefully acknowledged.

The special property of the actinide mass region is that nuclei belonging to this group are radioactive and undergo different ground state processes, such as alpha decay, cluster radioactivity (CR), heavy particle radioactivity (HPR), and spontaneous fission (SF). In this study, the probable radioactive decay modes of the heavy mass region (Z = 89−102) are studied within the framework of the preformed cluster model (PCM). In the PCM, the radioactive decay modes are explored in terms of the preformation probability () and penetration probability (P) at the turning point , where the penetration of fragments is initiated [R = R (touching state) + (neck length parameter)]. First, the alpha decay half-lives are calculated for light and heavy nuclei, and points are obtained by optimizing the neck length parameter. These points are further employed to fix the Q-value dependent turning point ((Q)). Then, using the ((Q)) relation, the decay half-lives are computed, and the calculated results are compared with the available theoretical and experimental data. The isotopical trend of and P is studied with respect to the mass number of the parent and daughter nucleus, respectively. The CR and HPR channels are also explored, and a comparison of calculated data is conducted with the available literature. Comparative analysis of the fragmentation potential and preformation probability is carried out for alpha decay and SF. The mass distribution of the nuclei is studied as a function of fragment mass (A ) by considering the spherical and hot-compact deformation of the decaying fragments. Finally, the most probable fission fragments are identified using the fragmentation structure, and the corresponding fission fragment total kinetic energy of the identified fragments is calculated and compared with available data, wherever applicable.

An empirical formula for the alpha decay half-lives

Using 377 available experimental data, we have obtained an empirical formula to calculate alpha decay half-lives based on Geiger–Nuttall law for even–even, even–odd, odd–even and odd–odd nuclei. The coefficients of Geiger–Nuttall law have been modified as a function of the atomic number of the parent nucleus and the orbital angular momentum. The obtained root mean square deviations from experimental half-lives for even–even, even–odd, odd–even and odd–odd nuclei are 0.3265, 0.5412, 0.4848 and 0.4353, respectively. For most nuclei, the obtained results from this formula are in good agreement with the experimental data. We compared our results with other formulas such as universal decay law, Royer, AKRA, MYQZR and Luo. Also, using this formula, we presented predictions for superheavy nuclei with [Formula: see text]–124 using the [Formula: see text]-values based on the finite range droplet model and Weizsäcker–Skyrme. It is found that the behavior of the half-life of alpha decay is sensitive to the used [Formula: see text]-values.

α and 2α decay of nuclei in the region 94≤Z≤101 using the modified generalized liquid drop model

The \ensuremath{\alpha} decay and $2\ensuremath{\alpha}$ decay of various isotopes of Pu, Am, Cm, Bk, Cf, Es, Fm, and Md in the mass region $A=218$ to 273 are investigated using the modified generalized liquid drop model (MGLDM) and universal decay law. The comparison of experimental alpha decay half-lives with the predicted half-lives proves the consistency of our calculations. As a result we broadened our investigation to also include a study of double alpha decay of these isotopes. There is a considerable interest in performing research on double alpha decay, as seen by the proposal submitted at CERN to investigate the double alpha radioactivity of $^{224}\mathrm{Ra}$. In view of this, the decay half-lives of most probable $2\ensuremath{\alpha}$ emitters, calculated using MGLDM by employing different preformation factors, are presented which can be beneficial for upcoming experimental investigations on this topic. A peak or dip in \ensuremath{\alpha} and $2\ensuremath{\alpha}$ decay half-life is witnessed which indicates the stability of parent or daughter isotopes correspondingly. Minimum and maximum half-lives for decay are observed when the daughter and parent nuclei, respectively, contain a magic number of neutrons. From our study, 126 and 162 are found as magic/semimagic numbers. A linear plot is obtained while plotting ${\mathrm{log}}_{10}{T}_{1/2}$ of all the isotopes against $Z{Q}^{\ensuremath{-}1/2}$, which emphasizes that our estimations are reliable.

Alpha Decay Half-Lives Calculation of Even-Even Nuclei in the62≤Z≤100Region using Woods-Saxon Potential

Alpha decay properties of even-even nuclei in the 62 ≤ Z ≤ 100 region are investigated within the Unified Fission Model based on a Modified Woods-Saxon potential. The computed alpha decay half-lives are compared to experimental data and are found to be in good agreement with it. The acquired pattern of the variation of alpha decay half-lives as a function of neutron number are explained by the nuclear shell effect. The experimental alpha decay energy Q is found to have an inverse relation with the alpha decay half-lives. This work has shown that the Unified Fission Model based on a Modified Woods-Saxon potential is sufficient to obtain the values of alpha decay half-lives.

Theoretical calculation of alpha decay half-lives of Neptunium nuclei using modified generalized liquid drop model

We considered the α-decay half-lives of neptunium (ZNp = 93) nuclei in the case of deformed nuclei in the range 219 ≤ A ≤ 239 using the generalized liquid-drop model (GLDM) with 1977 nuclear proximity potential suggested by Blocki et al. (1977) [29]. Also, we analyzed the α-decay half-lives of Np isotopes within the WKB method and the Deformed Proximity Potential Model (DPPM). We consider the quadrupole and hexadecapole deformations at θ=0, θ=30, θ=45, and θ=90 degrees. The calculated half-lives and the alpha decay branching ratios are compared with experimental data and are in good agreement. We compared the results obtained with the corresponding experimental data and with the models UNIV, UDL, SemFIS, the Coulomb and Proximity Potential Model (CPPM), SLB and Royer and it is found that they match well over a wide range. The calculated results are in reasonable agreement with the experimental data. Therefore, DPPM gives reliable and accurate results for favored α-decays in the neptunium mass region.