Examination of α-decay half-lives of undetected transfermium isotopes

2020 ◽  
Vol 29 (10) ◽  
pp. 2050085
Author(s):  
Nguyen Nhu Le ◽  
Nguyen Ngoc Duy
Keyword(s):  
Half Life ◽  
Spontaneous Fission ◽  
Theoretical Calculations ◽  
Q Value ◽  
Calculation Methods ◽  
Α Decay ◽  
Decay Modes ◽  
Predicted Values ◽  
Semi Empirical ◽  
Q Values

This study reports the [Formula: see text]-decay half-lives of 39 transfermium isotopes with [Formula: see text], most of which have not been observed. The half-lives were calculated using micro–macroscopic approaches and semi-empirical formulae, applying current [Formula: see text]-decay Q-values from the latest mass database, AME2016. These results were compared to predicted values in previous works to evaluate the efficiency of and difference between various calculation methods. We found that the [Formula: see text]-resonance approach used in a previous study is not appropriate to predict though most other approaches are mutually consistent. An uncertainty of 70% was observed in the present theoretical calculations, similar to that observed in measurements. A Q-value uncertainty of 10% can lead to a large variation of 3 orders of magnitude in predicted [Formula: see text]-decay half-life. We also found that the dominance of either [Formula: see text] decay or spontaneous fission is unclear for the isotopes with [Formula: see text]–[Formula: see text], whereas most of the nuclei of [Formula: see text]–[Formula: see text] can be clearly identified as [Formula: see text] emitters. Finally, we provide the updated [Formula: see text]-decay half-lives for the isotopes of interest, including their uncertainties and corresponding decay modes.

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

2020 ◽  
pp. 2050096
Author(s):  
S. A. Seyyedi
Keyword(s):  
Empirical Formula ◽  
Half Life ◽  
Cluster Model ◽  
Spontaneous Fission ◽  
Alpha Decay ◽  
Nucleon Nucleon ◽  
Empirical Formulas ◽  
Density Dependent ◽  
Double Folding ◽  
Semi Empirical

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.

The alpha-decay chains and decay mode predictions of the nuclei Z = 118, 119 and 120

2020 ◽  
Vol 29 (07) ◽  
pp. 2050053
Author(s):  
F. Koyuncu ◽  
A. Soylu
Keyword(s):  
Decay Mode ◽  
Half Life ◽  
Spontaneous Fission ◽  
Theoretical Models ◽  
Alpha Decay ◽  
Quantization Condition ◽  
Experimental Investigations ◽  
Universal Curve ◽  
Wkb Method ◽  
Decay Modes

The alpha decay (AD) chains of the nuclei having [Formula: see text], 119 and 120 have been investigated in terms of different theoretical models. Decay mode results that are presented in this study have been probed over the possible isotopes of the aforementioned nuclei. In the decay mode predictions, the formula of Bao et al. and the formula proposed by Soylu have been used to calculate the spontaneous fission (SF) half-lives. The AD half-lives have been computed by using the Denisov and Khuedenko, Royer, Horoi, the universal decay law (UDL), the Viola–Seaborg–Sobiczewski (VSS), the universal curve (UNIV) formulas and Wentzel–Kramers–Brillouin (WKB) approximation with Bohr–Sommerfeld quantization condition for the nuclei that have the measured experimental half-lives. Therefore, the rms values of the results of the related expressions and WKB method have been determined, in this way, AD half-life calculations of the [Formula: see text], 119 and 120 nuclei have been performed. According to the obtained results, SF half-life values for Bao et al. and Soylu are quite different from one approach to another, the predictions on decay modes of the [Formula: see text], 119 and 120 nuclei show differences. The decay modes produced by using different models used in this study would be important for the predictions of the future experimental investigations.

Systematic study of alpha-decay of super-heavy isotopes with Z = 120–126

2021 ◽  
pp. 2150033
Author(s):  
S. A. Seyyedi
Keyword(s):  
Spontaneous Fission ◽  
Alpha Decay ◽  
Nucleon Nucleon ◽  
Decay Modes ◽  
Nucleon Nucleon Interaction ◽  
Fragmentation Potential ◽  
Double Folding ◽  
Semi Empirical ◽  
Empirical Approaches ◽  
Good Agreement

Alpha-decay half-lives of the even–even superheavy isotopes with proton numbers [Formula: see text] have been calculated within the cluster model. The alpha-daughter potential was constructed by employing the density-dependent double-folding model with a realistic nucleon–nucleon interaction whose exchange part has a finite range approximation. The half-lives were calculated using Wentzel–Kramers–Brillouin (WKB) approximation with the alpha preformation factor. The results have shown that the computed alpha-decay half-lives were in good agreement with their counterpart calculated by different semi-empirical approaches. The obtained results have also shown a negative linear relationship between the logarithm of the preformation factor and the fragmentation potential for the understudy isotopes. Also, the calculated results have shown that isotopes [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] had longer half-lives than their adjacent isotopes, which indicates that the corresponding neutron or proton numbers have a magical or semi-magical properties. Furthermore, we have studied the competition between alpha-decay and spontaneous fission to predict possible decay modes from the even–even isotopes [Formula: see text]. The results revealed that the isotopes [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] had alpha-decay as a predominant mode of decay and the nuclei [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] could not survive from the spontaneous fission. We hope that the theoretical prediction could be helpful for future investigation in this field.

A comparative study of α-decay and spontaneous fission for Z = 120 superheavy isotopes

2020 ◽  
Vol 29 (05) ◽  
pp. 2050025
Author(s):  
S. A. Seyyedi
Keyword(s):  
Binding Energy ◽  
Comparative Study ◽  
Spontaneous Fission ◽  
Decay Chain ◽  
Superheavy Nuclei ◽  
Empirical Formulas ◽  
Α Decay ◽  
Hartree Fock ◽  
Effective Force ◽  
Semi Empirical

In this study, we have investigated the [Formula: see text]-decay chains of even–even superheavy nuclei [Formula: see text] in the range of [Formula: see text]. The Hartree–Fock–Bogoliubov model is used to calculate the binding energy of these superheavy nuclei. We have included the so-called SkP skyrme function as an effective force and the quadruple deformations. The semi-empirical formulas are used in the reproducing [Formula: see text]-decay and spontaneous fission half-lives of these superheavy nuclei. By studying the decay chains of the Z = 120 isotopes and comparing them with the half-lives of spontaneous fission, it is predicted that the elements [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text],[Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are more stable than the neighboring isotopes in their parent [Formula: see text]-decay chain. The corresponding neutron and proton numbers represent magical behavior that is in agreement with the numbers predicted before. In this range, the predicted nuclei are found to have large enough half-lives to synthesize them in a laboratory.

Semi-empirical formula for spontaneous fission half life time

2010 ◽  
Vol 832 (3-4) ◽  
pp. 220-232 ◽  
Author(s):  
K.P. Santhosh ◽  
R.K. Biju ◽  
Sabina Sahadevan
Keyword(s):  
Empirical Formula ◽  
Half Life ◽  
Spontaneous Fission ◽  
Life Time ◽  
Semi Empirical

Development of designing and implementation method of magnetic execution unit of downhole valve for the bottomhole assembly

2020 ◽  
pp. 38-44
Author(s):  
I.Y. Shirali ◽  
◽  
V.Yu. Tsivilitsin ◽  
İ.B. Bondar ◽  
R.A. Hasanov ◽  
...  
Keyword(s):  
Experimental Data ◽  
Theoretical Calculations ◽  
Calculation Methods ◽  
Well Drilling ◽  
Power Characteristics ◽  
Drilling Tools ◽  
Execution Unit ◽  
Implementation Method ◽  
Oil Gas ◽  
Gas Bearing

The structure of two types of magnetic valve is offered and the calculation methods of their pull-in force developed as well. The formulas of calculation of pull-in force in the main area of valves’ power characteristics are obtained. Experimental data are in alignment with theoretical calculations. Power characteristics of offered structures of magnetic valves may be changed in terms of the offered structural execution of magnetic valves. Experimental test of obtained formulas has been carried out. The ways of changing the power characteristics of magnetic valves in accordance with the requirements of certain applications are presented. The structures of magnetic reversing valves for drilling tools used in well drilling in various oil-gas bearing areas of SOCAR have been developed.

The spontaneous fission half-life of 244Cm

1970 ◽  
Vol 32 (3) ◽  
pp. 769-775 ◽  
Author(s):  
David Maxwell Barton ◽  
Philip Grant Koontz
Keyword(s):  
Half Life ◽  
Spontaneous Fission

scholarly journals Low Pressure Gas Electron Diffraction: an Experimental Setup and Case Studies

2020 ◽  
Author(s):  
Yury Vishnevskiy ◽  
Sebastian Blomeyer ◽  
Christian G. Reuter
Keyword(s):  
Electron Diffraction ◽  
Benzoic Acid ◽  
Low Pressure ◽  
Molecular Structures ◽  
Gas Electron Diffraction ◽  
Experimental Setup ◽  
Critical Comparison ◽  
Diffraction Patterns ◽  
Predicted Values ◽  
Semi Empirical

<div>Principles of low pressure gas electron diffraction(LPGED) are introduced. An experimental setup has</div><div>been constructed for measuring electron diffraction patterns of gaseous samples at pressures below 10−3</div><div>mbar. Test measurements have been performed for benzoic acid at T = 287 K corresponding to a vapor </div><div>pressure of the substance P = 2 × 10−4 mbar, for iodoform CHI3 at T = 288 K (P = 4 × 10−4 mbar) and for carbon tetraiodide CI4 at T = 290K (P = 1 × 10−4 mbar). Due to the low experimental temperature thermal decomposition of CI4 has been prevented, which was unavoidable in previous classical measurements at higher temperatures.</div><div>From the obtained data the molecular structures have been successfully refined. The most important</div><div>semi-empirical equilibrium molecular parameters are re(Car–Car)av = 1.387(5) Å in benzoic acid, re(C–I)</div><div>= 2.123(3) Å in iodoform and re(C–I) = 2.133(7) Å in carbon tetraiodide. The determined parameters</div><div>showed consistency with theoretically predicted values. A critical comparison with results of the earlier</div><div>investigations has also been done.</div>

Beta-decay half-lives of the extremely neutron-rich nuclei in the closed-shell N = 50, 82, 126 groups

2021 ◽  
Author(s):  
Nguyen Kim Uyen ◽  
Kyung Yuk Chae ◽  
NgocDuy Nguyen ◽  
DuyLy Nguyen
Keyword(s):  
Half Life ◽  
Random Phase ◽  
Closed Shell ◽  
Decay Rates ◽  
Magic Numbers ◽  
Β Decay ◽  
R Process ◽  
Neutron Rich Isotopes ◽  
Semi Empirical ◽  
The Impact

Abstract The β--decay half-lives of extremely neutron-rich nuclei are important for understanding nucleosynthesis in the r-process. However, most of their half-lives are unknown or very uncertain, leading to the need for reliable calculations. In this study, we updated the coefficients in recent semi-empirical formulae using the newly updated mass (AME2020) and half-life (NUBASE2020) databases to improve the accuracy of the half-life prediction. In particular, we developed a new empirical model for better calculations of the β--decay half-lives of isotopes ranging in Z = 10 – 80 and N = 15-130. We examined the β--decay half-lives of the extremely neutron-rich isotopes at and around the neutron magic numbers of N = 50, 82, and 126 using either five different semi-empirical models or finite-range droplet model and quasi-particle random phase approximation (FRDM+QRPA) method. The β--decay rates derived from the estimated half-lives were used in calculations to evaluate the impact of the half-life uncertainties of the investigated nuclei on the abundance of the r-process. The results show that the half-lives mostly range in 0.001 < T1/2 < 100 s for the nuclei with a ratio of N/Z < 1.9; however, they differ significantly for those with the ratio of N/Z > 1.9. The half-life differences among the models were found to range from a few factors (for N/Z < 1.9 nuclei) to four orders of magnitude (for N/Z > 1.9). These discrepancies lead to a large uncertainty, which is up to four orders of magnitude, in the r-process abundance of isotopes. We also found that the multiple-reflection time-of-flight (MR-TOF) technique is preferable for precise mass measurements because its measuring timescale applies to the half-lives of the investigated nuclei. Finally, the results of this study are useful for studies on the β-decay of unstable isotopes and astrophysical simulations.

Quantitative adjustment of spherical aberration for aspheric refractive surgery: A Pilot Study

2021 ◽  
Author(s):  
Jun Zhang ◽  
Li Zheng ◽  
Xia Zhao ◽  
Jindong Gao ◽  
Yixuan Zhang ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Pilot Study ◽  
Refractive Surgery ◽  
Spherical Aberration ◽  
Q Value ◽  
D Values ◽  
Q Values ◽  
Corneal Tomography

Abstract Background: The aim of the study is to introduce the acquisition of target diameter spherical aberration in term of diopter (SA-D), and to report the distribution of SA-D in patients with myopia. Methods: This was a retrospective study of patients who underwent therapeutic refractive surgery at Hangzhou MSK Eye Hospital between 10/2018 and 12/2018. The corneal Q values and apex curvature of the anterior and posterior surfaces were measured at 3.0, 4.0, 5.0, 6.0, and 7.0 mm of aperture diameters using corneal tomography. Results: In total, 531 females and 384 males were included. The anterior corneal SA-D values were: 0.39±0.19, 0.63±0.27, 0.97±0.36, 0.90±0.30, and 0.83±0.29 D at 3.0, 4.0, 5.0, 6.0, and 7.0 mm; the whole corneal values were: 0.26±0.20, 0.44±0.27, 0.70±0.36, 0.66±0.30, and 0.59±0.28 D. SE was positively correlated with anterior corneal peripheral Q-value and SA-D and whole ocular peripheral SA-D. Conclusions: Both corneal anterior and posterior Q values of myopia patients decreased while diameter increased. Both anterior and whole corneal SA-D increases significantly while diameter increases within 5mm, and both anterior and whole corneal SA-D outside 5mm decreases slightly while diameter increases. SE was positively correlated with anterior corneal peripheral Q-value and SA-D and whole ocular peripheral SA-D.

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