Using the finite temperature quasi-particle random phase approximation (FTQRPA) on the basis of finite temperature Skyrme-Hartree-Fock + BCS method, we study $β^-$-decay half-lives for even-even neutron magic nuclei with N=82 in a finite temperature environment. We find that the $β^-$-decay half-life first decreases as the temperature increases for all the nuclei we study, although the thermal effect is found to be small at temperatures relevant to r-process nucleosynthesis. Our calculations indicate that the half-life begins to increase at high temperatures for open shell nuclei. We discuss this behavior in connection to the pairing phase transition.
$β$-decay half-lives of neutron-rich nuclei around $N=82$ are key data to understand the $r$-process nucleosynthesis. We performed large-scale shell-model calculations in this region using a newly constructed shell-model Hamiltonian, and successfully described the low-lying spectra and half-lives of neutron-rich $N=82$ and $N=81$ isotones with $Z=42-49$ in a unified way. We found that their Gamow-Teller strength distributions have a peak in the low-excitation energies, which significantly contributes to the half-lives. This peak, dominated by $ν0g_{7/2} \to π0g_{9/2}$ transitions, is enhanced …
Alpha and cluster decay half lives for W isotopes in the range between 2p drip line and beta stability line are studied. The sensitivity of different Skyrme parametrizations in predicting the alpha decay and probable cluster decay modes from W isotopes have been analysed. The half lives are calculated using UDL. Predicted half lives are compared with ELDM and also with available experimental values. The study also revealed the role of neutron shell closure in cluster decay process.
Nuclear $β$-decay half-lives in the relativistic point-coupling model
采用自洽质子-中子准粒子无规相近似方法，计算了丰中子偶偶核的$8\leqslant Z \leqslant 30$衰变半衰期。计算中采用了新提出的非线性点耦合有效相互作用PC-PK 1。研究发现，等势质子-中子对相互作用能显著降低$β$的衰变半衰期。与同位旋相关的isoscope质子-中子配对强度，我们的结果很好地再现实验$β$衰变半衰期，虽然配对强度没有调整使用本研究中计算的半衰期。
Evaluated $2β^{-}(2ν)$ half-lives and their systematics were reexamined in the framework of a phenomenological approach. Decay rate dependence on nuclear deformation, decay energy, shape coexistence, and forbidden transitions was observed. The following analysis showed distinct impacts of decay energy on half-lives and deformation parameters on effective nuclear matrix elements. These findings were used to predict $T_{1/2}$ for 36 isotopes of interest. Present work results were compared with published data.
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.
We present results for $β$-decay half-lives based on a new recipe for calculation of phase space factors recently introduced. Our study includes $fp$-shell and heavier nuclei of experimental and astrophysical interests. The investigation of the kinematics of some $β$-decay half-lives is presented, and new phase space factor values are compared with those obtained with previous theoretical approximations. Accurate calculation of nuclear matrix elements is a pre-requisite for reliable computation of $β$-decay half-lives and is not the subject of this paper. This paper explores if improvements in…
In the present work, we systematically study the two-proton (2p) radioactivity half-lives of nuclei close to the proton drip line within a modified Gamow-like model. Using this model, the calculated 2p radioactivity half-lives can well reproduce the experimental data. Moreover, we use this model to predict the 2p radioactivity half-lives of 22 candidates whose 2p radioactivity is energetically allowed or observed but not yet quantied in evaluated nuclear properties table NUBASE2016. The predicted results are in good agreement with the ones obtained by using Gamow-like model, effective liquid d…
On spontaneous fission and alpha-decay half-lives of atomic nuclei
结果表明，仅用一个可调参数--半径常数的类伽莫夫模型，能很好地再现质子数大于50的所有偶偶核的α衰变半衰期。当引入额外的位阻因子时，奇A和奇-奇同位素的系统学也能得到很好的描述。相似模型基于W. J. Swiatecki从1955年开始提出了一种计算超锕系元素核自发裂变半衰期的方法。所获得的数据再现精度优于更先进的理论。
The $α$- decay half-lives of the superheavy nuclei are systematically studied using different versions of proximity potential and a exact method to calculate Coulomb potential between spherical and deformed nuclei in the framework of the double folding model. To reproduce the $α$-decay half-life, the experimental $α$-decay energy and Wentzel-Kramers-Brillouin approximation have been used. It is found that the computed values by the Ng$\hat{o}$ 80 are in good compromise with the experimental half-lives in comparison with other versions. Also, by using this version and within $Q_{WS4}$ for deter…
In the present work, we study α decay and proton emission half-lives within the modified Gamow-like model, which introduces the effects of the nucleus's deformation. The calculations show that it is necessary to consider the deformation in the calculation for nuclei far from the shell. Moreover, we use the improved model to predict the proton emission half-lives of the nuclei far from the shell. The calculation results indicate that our model is in good agreement with most models. Furthermore, the deformed Gamow-like model is used to find the following neutron magic number. This work is meanin…
We considered the systematics of $α$-decay (AD) half-life (HL) of super-heavy nuclei versus the decay energy and the total $α$-kinetic energy. We calculated the HL using the experimental Q_{$α$} values. The computed half-lives are compared with the experimental data and also with the existing empirical estimates and are found in good agreement. Also, we obtained $α$-preformation factors from the ratio between theoretical and experimental results for some super heavy nuclei SHN and evaluated the standard deviation. The results indicate the acceptability of the approach.
We have applied the Coulomb and proximity potential model,CPPM to calculate the half lives for various clusters decay of the selected even-even isotopes of the chosen nuclei. These nuclei are Hf, W, Os, Pt, and Hg in the 5d transition metal region in the periodic table with atomic number 72 greater or equal Z less than or equal 80. Furthermore, the half-lives are calculated using the universal formula for cluster decay. The calculated half-lives of alpha decay for the chosen isotopes are in good agreement with the experimental data, especially with the CPPM results. The alpha and cluster decay…
In the present work we calculate the allowed $β^-$-decay half-lives of nuclei with $Z = 20 -30$ and N $\leq$ 50 systematically under the framework of the nuclear shell model. A recent study shows that some nuclei in this region belong to the island of inversion. We perform calculation for $fp$ shell nuclei using KB3G effective interaction. In the case of Ni, Cu, and Zn, we used JUN45 effective interaction. Theoretical results of $Q$ values, half-lives, excitation energies, log$ft$ values, and branching fractions are discussed and compared with the experimental data. In the Ni region, we also c…
In recent years, artificial neural network (ANN) has been successfully applied in nuclear physics and some other areas of physics. This study begins with the calculations of α-decay half-lives for some neutron-deficient nuclei using Coulomb and proximity potential model (CPPM), temperature dependent Coulomb and proximity potential model (CPPMT), Royer empirical formula, new Ren B (NRB) formula, and a trained artificial neural network model (TANN ). By comparison with experimental values, the ANN model is found to give very good descriptions of the half-lives of the neutron-deficient nuclei. Mo…
The half-lives of proton radioactivity of proton emitters are investigated theoretically by using KDE0v1 Skyrme interaction. The total barrier potential in the proton radioactive nuclei is calculated as the sum of the nuclear, Coulomb and centrifugal contributions. The Hartree-Fock nuclear density distributions is used in calculating the nuclear as well as the Coulomb interaction potentials. The quantum mechanical tunneling probability is calculated within the WKB approximation. These calculations provide reasonable estimates for the observed proton radioactivity lifetimes.
For $α$ decay half-life calculations in this work, the Coulomb and proximity potential model with a new semiempirical formula for diffuseness parameter developed in previous work [Phys. Rev. C 100, 024601 (2019)] is used. The present model in this work is compared with the generalized liquid-drop model (GLDM), universal decay law (UDL), and experimental half-lives in the region $Z=104-118$. Next, the predicted half-lives of 51 superheavy nuclei (SHN) with $Z=122-125$ by the present model are compared with those of GLDM, and UDL. The present model is revealed to be more accurate in reproducing …
Prediction of Alpha-Decay Half-Lives of Actinide Nuclei Using the DDM3Y Effective Interaction Potential
Govt. First Grade College, Chikkaballapur（奇克巴拉布尔政府第一等级学院）；Govt. First Grade College, Devanahalli（德瓦纳哈利政府第一等级学院）；Government First Grade College, Nanjangud（南詹古德政府第一等级学院）；R V College of Engineering, Bengaluru（班加罗尔R V工程学院）
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…
In the present work, we systematically study the proton radioactivity half-lives of 33 spherical nuclei based on the relationship between the Skyrme parameters and the macroscopic quantities of nuclear matter. Using the two-potential approach with the spherical Skyrme-Hartree-Fock model, the correlation between proton radioactivity half-life and macroscopic quantities was analyzed. Moreover, we obtained a new Skyrme parameter set by fitting the two most weighted macroscopic quantities. Compared with Skyrme parameters MSL0 and the theoretical model of proton radioactivity UDLP, the theoretical …
Although Geiger-Nuttall (GN) law gives a single straight line, if we consider the experimental data of alpha particle emitters including heavy and super heavy nuclei with proton numbers as large as 118, instead of getting a single linear path we observe several linear segments with different slopes and intercepts. This problem is overcome when the experimental results in logarithm form are plotted as a function of Viola-Seaborg (VS) parameters with values of parameters set by hand. By using the fundamental principle of decay, we derive a formula of logarithm of half-lives in terms of well-defi…
Ab-initio calculations of nuclear masses, the binding energy and the $α$ decay half-lives are intractable for heavy nucleus, because of the curse of dimensionality in many body quantum simulations as proton number($\mathrm{N}$) and neutron number($\mathrm{Z}$) grow. We take advantage of the powerful non-linear transformation and feature representation ability of deep neural network(DNN) to predict the nuclear masses and $α$ decay half-lives. For nuclear binding energy prediction problem we achieve standard deviation $σ=0.263$ MeV on 10-fold cross validation on 2149 nuclei. Word-vectors which a…
In this work, we systematically study the two-proton($2p$) radioactivity half-lives using the two-potential approach while the nuclear potential is obtained by using Skyrme-Hartree-Fock approach with the Skyrme effective interaction of {SLy8}. For true $2p$ radioactivity($Q_{2p}$ $>$ 0 and $Q_p$ $< $0, where the $Q_p$ and $Q_{2p}$ are the released energy of the one-proton and two-proton radioactivity), the standard deviation between the experimental half-lives and our theoretical calculations is {0.701}. In addition, we extend this model to predict the half-lives of 15 possible $2p$ radioactiv…
Artificial neural networks are trained by a standard backpropagation learning algorithm with regularization to model and predict the systematics of -decay of heavy and superheavy nuclei. This approach to regression is implemented in two alternative modes: (i) construction of a statistical global model based solely on available experimental data for alpha-decay half-lives, and (ii) modeling of the {\it residuals} between the predictions of state-of-the-art phenomenological model (specifically, the effective liquid-drop model (ELDM)) and experiment. Analysis of the results provide insights on th…
Nuclear radial distance is a prerequisite for generating any alpha-decay half-life formula by taking a suitable effective potential. We study the emission process of alpha particles from an isolated quasi-bound state generated by an effective potential to a scattering state. The effective potential is expressed in terms of Frahn form of potential which is exactly solvable and an analytical expression for half-life is obtained in terms of Coulomb function, wave function and the potential. We then derive a closed form expression for the decay half-life in terms of the parameters of the potential…
In present work, the unfavored $\mathcalα$ decay half-lives and $\mathcalα$ preformation probabilities of closed shell nuclei related to ground and isomeric states around $Z=82$, $N=82$ and 126 shell closures are investigated by adopting two-potential approach from the perspective of valence nucleon (hole) and isospin asymmetry of the parent nucleus. The results indicate that $\mathcalα$ preformation probability is linear dependence on $N_p N_n$ or $N_p N_n I$, the same as the case of favored $\mathcalα$ decay in our previous work [X.-D. Sun \textit{et al.}, Phys. Rev. C 94, 024338 (2016)]. $N…
