Nuclear systematics of the heavy elements—II Lifetimes for alpha, beta and spontaneous fission decay

This is a short review of methods and results of calculations of fission barriers and fission halflives of even-even superheavy nuclei. An approvable agreement of the following approaches is shown and discussed: The macroscopic-microscopic approach based on the stratagem of the shell correction to the liquid drop model and a vantage point of microscopic energy density functionals of Skyrme and Gogny type selfconsistently calculated within Hartree-Fock-Bogoliubov method. Mass parameters are calculated in the Hartree-Fock-Bogoliubov cranking approximation. A short part of the paper is devoted to the nuclear fission dynamics. We also discuss the predictive power of Skyrme functionals applied to key properties of the fission path of 266 Hs. It applies the standard techniques of error estimates in the framework of a χ 2 analysis.

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“…To estimate α-decay half-lives, we used the standard Viola-Seaborg expression [59] with the parameters from Ref. [60].…”

Section: Skyrme Type Functionalmentioning

confidence: 99%

Fission barriers and probabilities of spontaneous fission for elements with Z≥ 100

et al. 2015

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“…Various theoretical prescriptions since 1930 [6] have been proposed. Some of these as well as some empirical observations have been reduced to analytical formulae [7][8][9][10][11][12] that connect Q α , and the Z,A of the parent nuclide and wherein coefficients are typically obtained from fits to known alpha half-lives. The underlying model's description of the potential barrier lies implicit in the formula's functional form and its coefficients and this in part determines the merit of the formula.…”

mentioning

confidence: 99%

The generalized liquid drop model alpha-decay formula: Predictability analysis and superheavy element alpha half-lives

Dasgupta‐Schubert

Reyes²

2007

Atomic Data and Nuclear Data Tables

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The predictive accuracy of the generalized liquid drop model (GLDM) formula for alpha decay half-lives has been investigated in a detailed manner and a variant of the formula with improved coefficients is proposed. The method employs the experimental alpha half-lives of the well-known alpha standards (REFERENCE) to obtain the coefficients of the analytical formula using the experimental Q α values (the DSR-E formula), as well as the finite range droplet model (FRDM) derived Q α values (the FRDM-FRDM formula). The predictive accuracy of these formulae were checked against the experimental alpha half-lives of an independent set of nuclei (TEST) that span approximately the same Z,A region as the standards and possess reliable alpha spectroscopic data, and were found to yield good results for the DSR-E formula but not for the FRDM-FRDM formula. The two formulae were used to obtain the alpha half-lives of super-heavy (SHE) and heavy nuclides where the relative accuracy was found to markedly improve for the FRDM-FRDM, which corroborates the appropriateness of the FRDM masses and the GLDM prescription for high Z,A nuclides. Further improvement resulted, especially for the FRDM-FRDM formula, after a simple linear optimization over the calculated and experimental half-lives of TEST was used to re-calculate the half-lives of the SHE and heavy nuclides. The advantage of this optimization was that it required no recalculation of the coefficients of the basic DSR-E or FRDM-FRDM formulae. The halflives for 324 medium-mass to super-heavy alpha decaying nuclides, calculated using these formulae and the comparison with experimental half-lives, are presented. Often the main and sometimes the only decay mode of these nuclei is alpha decay.For the SHE, the product nuclides of hot-fusion heavy ion reactions closest to the shell model predicted Island of Stability, decay by the emission of alpha particles. Chains of successive alpha decays are terminated by spontaneous fission as the shell-stabilized region is left behind [5,2].Thus identifying and characterizing the alpha decay sequences form a crucial part of the identification of SHE. Theoretically the mechanism is described by quantum mechanical tunneling through the potential energy barrier leading from the mother nucleus to the daughter nucleus and alpha particle. Consequently the predicted half-lives remain very sensitive to the shape and energetics of the barrier which as such, serve to test the particular theoretical model of the potential energy surfaces of these exotic nuclei. Various theoretical prescriptions since 1930 [6] have been proposed. Some of these as well as some empirical observations have been reduced to analytical formulae [7][8][9][10][11][12] that connect Q α , and the Z,A of the parent nuclide and wherein coefficients are typically obtained from fits to known alpha half-lives. The underlying model's description of the potential barrier lies implicit in the formula's functional form and its coefficients and this in part determines the merit of the formula....

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“…We have estimated α-decay half-lives T α corresponding to our calculated Q α values by use of the Viola-Seaborg systematics [18] with parameter values that were determined in an adjustment that included new data for even-even nuclei [19]. The nucleus 272 110 has a cal- Applications of our model to the calculation of β-decay half-lives and β-delayed neutron emission is discussed elsewhere [20,21].…”

Section: Modelmentioning

confidence: 99%

Applications of a global nuclear structure model to studies of the heaviest elements

Möller

Nix

1994

Journal of Alloys and Compounds

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Abstract. We present some new results on heavy-element nuclear-structure properties calculated on the basis of the finite-range droplet model and folded-Yukawa single-particle potential. Specifically, we discuss calculations of nuclear groundstate masses and microscopic corrections, α-decay properties, β-decay properties, fission potential-energy surfaces, and spontaneous-fission half-lives. These results, obtained in a global nuclear-structure approach, are particularly reliable for describing the stability properties of the heaviest elements.

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Nuclear systematics of the heavy elements—II Lifetimes for alpha, beta and spontaneous fission decay

Cited by 558 publications

References 25 publications

Fission barriers and probabilities of spontaneous fission for elements with Z≥ 100

Fission barriers and probabilities of spontaneous fission for elements with Z≥ 100

The generalized liquid drop model alpha-decay formula: Predictability analysis and superheavy element alpha half-lives

Applications of a global nuclear structure model to studies of the heaviest elements

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