Decay Properties Research Articles

Macroscopic–microscopic calculations of the ground state properties of Z = 120 isotopes and their α-decay chains

One of the substantial successes achieved in nuclear physics in the last two decades was the synthesis of dozens of isotopes of new elements up to [Formula: see text]Og, which closed the seventh row of the periodic table and inspired the ambition of adding more elements. This work aims to study extensively the ground state structure and decay properties of proposed [Formula: see text] isotopes. We employed Macroscopic–microscopic scheme based on the Skyrme energy density functional, the Woods–Saxon single-particle potential and Strutinsky’s method to find the structure properties, in a multidimensional deformation space. The same nucleon–nucleon potential is used to find the [Formula: see text]-decay half-life, within the Preformed Cluster Model. For 45 [Formula: see text]120 isotopes, the total energy surfaces, ground state masses, binding energy, deformations and fissionability are determined. The [Formula: see text]-values of the different competing decays and [Formula: see text]-decay half-lives are investigated based on the obtained structure. The results indicate the [Formula: see text]120 isotopes to be the most bound among the studied isotopes. The smallest fission barriers are indicated for the [Formula: see text]120 isotopes. The [Formula: see text]120 isotopes showed the longer half-lives against [Formula: see text]-decay, with an order of [Formula: see text]. The longest half-lives are estimated for the [Formula: see text]120 ([Formula: see text] and [Formula: see text]120 ([Formula: see text] isotopes. The longest full decay chain ending with the stable [Formula: see text]Pb nucleus is anticipated for the [Formula: see text]120 isotope. The shortest decay chain of [Formula: see text]120 terminates after three [Formula: see text]-decays by the spontaneous fission of [Formula: see text]Fl.

Exponential decay rate of a nonlinear suspension bridge model by a local distributed and boundary dampings

In this paper, we investigate the decay properties of the unconstrained one dimensional suspension bridge model. With only partial damping acting on one or on both equations and with boundary dampings, we prove that the first order energy is decaying exponentially, our method of proof is based on the energy method to build the appropriate Lyapunov functional. Moreover, we develop a numerical algorithm which is based on the finite element method to approximate the spatial variable and the Crank–Nicolson type of symmetric difference scheme to discretize the time derivative, and also a Picard type iteration process for solving the system of nonlinear equations obtained by discretization. At the end, we present some numerical experiments to illustrate our theoretical results.

Hidden-charm pentaquark states through current algebra: from their production to decay * *Supported by the National Natural Science Foundation of China (11722540, 12075019), the Jiangsu Provincial Double-Innovation Program (JSSCRC2021488), and the Fundamental Research Funds for the Central Universities

There may be seven hadronic molecular states. We construct their corresponding interpolating currents and calculate their masses and decay constants using QCD sum rules. Based on these results, we calculate their relative production rates in decays using current algebra, that is, , where and are two different states. We also study their decay properties via Fierz rearrangement and further calculate these ratios in the mass spectrum, that is, . Our results suggest that the molecular states of and may be observed in future experiments.

Effect of Coriolis mixing on lifetime of isomeric states in heavy nuclei

The effect of Coriolis $K$ mixing on the $\ensuremath{\gamma}$ decay of one-quasiparticle isomeric states is examined in transfermium nuclei with neutron number $N=153$. We consider a core-plus-quasiparticle coupling in which the $K$ mixing sharply increases if the isomeric quasiparticle state closely approaches the rotational state with the same angular momentum $I$, but built on another quasiparticle state which is either directly coupled to the isomeric ($\mathrm{\ensuremath{\Delta}}K=1$) or connected with it through the intermediate mixing quasiparticle orbitals ($\mathrm{\ensuremath{\Delta}}K>1$). This mechanism is likely to explain the 38-ns ${K}^{\ensuremath{\pi}}=7/{2}^{+}$ isomer in $^{251}\mathrm{Cf}$ which is quasidegenerated with an ${I}^{\ensuremath{\pi}}=7/{2}^{+}$ rotation state built on ${K}^{\ensuremath{\pi}}=1/{2}^{+}$. Our model explains the enhancement of its decay by three orders of magnitude compared to the ${K}^{\ensuremath{\pi}}=7/{2}^{+}$ isomer in $^{249}\mathrm{Cm}$. We suggest that the same mechanism could be of general importance for the isomer decay properties in a wide range of heavy odd-mass nuclei.

Vacuum polarization energy decline and spontaneous positron emission in QED under Coulomb supercriticality

The properties of QED-vacuum polarization, caused by the supercritical external Coulomb source with charge $Z$ and size $R$, are explored in an essentially nonperturbative approach with emphasis on the vacuum energy ${\mathcal{E}}_{\mathrm{VP}}$ (where VP stands for vacuum polarization.) It is shown that in the supercritical region ${\mathcal{E}}_{\mathrm{VP}}$ turns out to be a decreasing function of the Coulomb charge, resulting in decay into the negative range as $\ensuremath{\sim}\ensuremath{-}{Z}^{4}/R$. Moreover, it is indeed the decline of ${\mathcal{E}}_{\mathrm{VP}}$, which provides the required energy for (presumably possible) positron emission. Found this way, properties of the resonance decay are in agreement with those achieved by other methods. The additional problems of spontaneous emission, caused by lepton number, are also discussed.

Structure and decay chain of fermium isotopes using relativistic mean-field approach

In this paper, we have analyzed the ground state structural properties of fermium-isotopes in the mass range [Formula: see text] within the relativistic mean-field with NL3[Formula: see text] and Relativistic Hartree–Bogoliubov approach with DD-ME2 parameter sets. The bulk properties, such as binding energy, root mean-square charge radius, quadruple deformation parameter, chemical potentials, two-neutron separation energy and differential two- neutron separation energy, are estimated for the above Fm- isotopic chain. All the calculated observables are compared with finite range droplet model (FRDM) predictions and experimental data wherever available. The analysis predicts the existence of shell closure in the neutron-rich region of the isotopic chain at [Formula: see text]. The decay properties such as the [Formula: see text]-decay energy and corresponding half-life for three decay chains i.e. [Formula: see text]Fm, [Formula: see text]Fm and [Formula: see text]Fm are studied. Six different empirical formulae, namely; Viola-Seaborg, Royer, modified B. Alex Brown, Parkhomenko–Sobiczewski, Universal decay law and modified universal decay law are employed to ascertain the numerical dependency of the half-life for each decay energy. A comparative study of [Formula: see text]-values and half-lives for these decay chains gives a good signature of the calculated results. The half-life calculations of three decay chains suggest that [Formula: see text]Pu, [Formula: see text]Pu, [Formula: see text]Pu are shell closure nuclei having maximum half-lives, whereas [Formula: see text]Fm, [Formula: see text]Fm and [Formula: see text]Fm are shell stabilized with lower half-lives.

Non-perturbative effects in the QED-vacuum energy exposed to the supercritical Coulomb field

Non-perturbative effects of the QED-vacuum reconstruction exposed to the supercritical Coulomb field are considered with emphasis on the behavior of the vacuum energy [Formula: see text]. It is shown that in the supercritical region [Formula: see text] turns out to be a decreasing function of the Coulomb source, resulting in decay into the negative range as [Formula: see text], and that it is indeed the decline of [Formula: see text], which provides the required energy for (presumably possible) positron emission. The properties of the resonance decay, found this way, are in agreement with those achieved by other methods. The additional problems of spontaneous emission, caused by lepton number conservation, are also discussed.

Li6AlGd(BO3)4: Sm3+ phosphors for orange-red light sources

A new class of Li6AlGd(BO3)4: Sm3+ phosphors were prepared via solid-state-reaction method and analyzed for orange-red light sources. The structure, morphology, distribution of particles, presence of various bonds responsible for optical properties, energy-transfer among the excited Sm3+ ions and decay properties were broadly studied. Most of the intense and sharp excitation transitions of Sm3+ in LAGBSmx phosphors appear in n-UV region and the emission spectra reveal 4G5/2 → 6H5/2, 7/2, 9/2, 11/2 transitions upon 408 nm n-UV wavelength excitation. The concentration was optimized to be 1.0 mol% for efficient orange-red emission. The CIE colour coordinates were obtained as (0.611, 0.388) for LAGBSmx phosphors with a negligible change with variation in concentration of Sm3+ ions. The decay profiles were well fitted to double-exponential function showing the occupation of Sm3+ in two different sites. The transfer of energy among the excited Sm3+ ions was possible through exchange interaction at higher concentrations. The emission of orange-red light shows its proficiency for solid-state lighting devices as well as red light source replacement in the design of white-LEDs.

Properties of B and Bs meson states in a nonrelativistic quark model with the inclusion of coupled channel effects

The mass spectra and decay properties of [Formula: see text] and [Formula: see text] mesons are obtained using the nonrelativistic potential model by applying the variational approach. The quark–anti-quark potential used in our model consists of a Hulthen potential and a confining linear potential. The hyper-fine interaction is introduced to obtain the splittings of the spin-singlet and triplet states, while the spin–orbit and tensor interactions provide the fine structure splittings. The model parameters and the wave functions that reproduce the mass spectra are used to investigate the decay properties of [Formula: see text] and [Formula: see text] mesons. The mass spectra of [Formula: see text] and [Formula: see text] mesons have been enhanced using coupled channel effects.

The assignments of the bottom mesons within the screened potential model and 3P0 model

In this work, we calculate the mass spectrum of the bottom mesons with a modified nonrelativistic quark model by involving the screening effect, and explore their strong decay properties within the 3P0 model. Our results suggest that the [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] could be reasonably assigned as the [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], respectively. The more precise measurements of the excited bottom mesons are crucial to confirm these assignments.

Development of Edible Coating from Gelatin Composites with the Addition of Black Tea Extract (Camellia sinensis) on Minimally Processed Watermelon (Citrullus lanatus).

The purpose of this research was to determine the effect of composite fish gelatin–chitosan edible coatings enriched with black tea extract on the physical, chemical, and fungal decay properties of minimally processed watermelons stored at ±4 °C for 13 days. In this study, tuna skin gelatin was extracted and used to prepare edible coating solutions which comprised 4% gelatin, 2% chitosan, 2% calcium lactate, 2% glycerol, and black tea extract (0%; 0.25%; 0.50%; 0.75%; 1%). The samples were coated using the layer-by-layer dipping technique. This study showed that composite fish gelatin–chitosan edible coating enriched with black tea extract maintained and improved weight loss, texture (hardness), color, pH, and total soluble solid antioxidant activity and prevented fungal decay on minimally processed watermelons stored at ±4 °C for 13 days. The development in this study of edible film and a coating prepared from fish gelatin–chitosan and the incorporation of black tea extract as an antioxidant or antimicrobial agent can be a new approach to preventing postharvest loss and increasing the shelf life of minimally processed watermelon.

Study of CP violation in hyperon decays at super-charm-tau factories with a polarized electron beam

Nonleptonic two-body weak decays of baryons are an important tool to probe the combined charge conjugation--parity symmetry ($CP$) violation. We explain why the decays of strange baryons provide complementary information to the decays of kaons. A model-independent parametrization of the nonleptonic decays of the $\mathrm{\ensuremath{\Lambda}}$ and $\mathrm{\ensuremath{\Xi}}$ baryons is reviewed, and the amplitudes are updated according to the latest experimental input. We demonstrate the potential of performing precision tests in strange baryon decays at the next-generation electron-positron $J/\ensuremath{\psi}$ factories with luminosity of ${10}^{35}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$. The copious production of spin-entangled hyperon-antihyperon pairs via the $J/\ensuremath{\psi}$ resonance allows for a direct comparison of the baryon and antibaryon decay properties. Using analytic approximations and numerical calculations, we study the quantitative impact of spin correlations and polarization in such $CP$ tests. We show that by using a longitudinally polarized electron beam the statistical precision of the $CP$ tests can be significantly improved compared to the experiments without polarized beams. Furthermore, we map out further directions for possible improvements, like analysis of incompletely reconstructed events or a combination of the isospin related processes. Altogether, these methods are promising for the observation of a statistically significant $CP$-violation signal with a strength corresponding to the standard model predictions. Our conclusions should encourage more detailed feasibility studies, including optimization of the measurement methods and studies of systematic effects. Finally, our results call for an update of the theory predictions with increased precision.

Theoretical Investigation of α-decay Chains of Fm-isotopes

Background: The theoretical and experimental investigations of decay properties of heavy and superheavy nuclei are crucial to explore the nuclear structure and reaction dynamics.
 Purpose: The aim of this study is to probe the α-decay properties of 243Fm and 245Fm isotopic chains using relativistic mean-field (RMF) approach within the framework of preformed cluster-decay model (PCM).
 Methods: The RMF densities are folded with the relativistic R3Y NN potential to deduce the nuclear interaction potential between the α particle and daughter nucleus. The penetration probability is calculated within the WKB approximation.
 Results: The α-decay half-lives of even-odd 243Fm and 245Fm isotopes and their daughter nuclei are obtained from the preformed cluster-decay model. These theoretically calculated half-lives are found to be in good agreement with the recent experimental measurements.
 Conclusions: The novel result here is the applicability of the scaling factor within the PCM as a signature for shell/sub-shell closures in α-decay studies. As such, we have also demonstrated that N=137, 139 and Z=94 corresponding to 231,233Pu could be shell/sub-shell closures. The least T1/2 is found at 243,245Fm which indicate their individual stability and α-decay as their most probable decay mode.

4α linear-chain state produced by Be9+Be9 collisions

The linear-chain (LC) structure provides significant insights into quantum many-body systems with geometric configurations. In this study, $4\ensuremath{\alpha}+2n$ LC was assessed in $^{18}\mathrm{O}$. The excitation energies, moment of inertia, and $\ensuremath{\alpha}$- and $^{9}\mathrm{Be}$-decay widths of the LC states were predicted using antisymmetrized molecular dynamics. We predict that there are two $4\ensuremath{\alpha}$ LC bands, ${K}^{\ensuremath{\pi}}={0}^{+}$ and ${K}^{\ensuremath{\pi}}={3}^{\ensuremath{-}}$, which exhibit different decay properties. We demonstrate that the ${K}^{\ensuremath{\pi}}={3}^{\ensuremath{-}}$ LC states can be verified by the head-on $^{9}\mathrm{Be}+^{9}\mathrm{Be}$ collision experiments because their states exhibited large decay widths in the $^{9}\mathrm{Be}+^{9}\mathrm{Be}$ channel.

Nuclear data evaluation for decay heat analysis of spent nuclear fuel over 1–100 k year timescale

Accurate nuclear data are essential in the evaluation of decay heat from spent nuclear fuel (SNF). The accuracy of such data was assessed using an approach that compares values reported in different evaluated libraries and determines whether discrepancies reflect inaccuracies in primary data. A short list of 43 isotopes which are most significant to SNF decay heat calculations over 1–100 k years was produced by combining generic reactor inventory code with decay heat analysis for undifferentiated SNF. Decay properties (half-lives and decay energies) and neutron interactions (cross section and fission yields) were compared from 6 evaluated libraries. Fission product (FP) discrepancies identified are 90Sr half-life, where inclusion of a single measurement significantly reduces the evaluated value; 95mNb beta energy, where DDEP evaluation omits the decay to the 95Mo ground state; 99Tc beta energy, where evaluations differ by approximately 10% with a variety of shape factors used; 126Sb/126mSb beta (JEF2.2/3.1.1/3.3) and electron energies (JEFF3.1.1), where intensity differences are reported; and 137Cs beta energy, where ENDF/B-VIII.0 and JEF3.3 evaluations use incorrect shape factors. For actinides, the major discrepancies identified were 237Np alpha energy (JEF2.2/3.1.1) and 225Ac electron energies (ENDF/B-VIII.0) but overall show less discrepancies during long-term disposal (0.1–100 ky) compared to FP’s during interim storage (1–100 years). Further assessments of the 90Sr half-life and the best shape factor for the 99Tc beta decay are needed to improve future decay heat analyses, which are important for designing future stores and evaluating schemes for possible heat recovery.

Spectroscopy characteristics and decay properties of plasma-embedded atoms in external electric and magnetic fields

This paper describes a computational approach within the framework of relativity theory for explaining the spectral and decay properties of atoms and ions embedded in a plasma and also in the presence of applied external electric and magnetic fields. It uses the configuration interaction approximation and the analytical potential derived from general ion-sphere theory to represent the atomic interactions within the plasma. In the model, the Dirac–Coulomb–Hamiltonian is reconstructed and the effects of the weak electric and magnetic field are treated as small perturbations. The eigenvalues for the orbitals and (radial) wave functions are obtained through the Dirac equations. A diagonalization is performed to include these plasma, electric, and magnetic terms. As an example, an environment with a hot-dense plasma and weak electric and magnetic fields is considered, where the interaction is much weaker than the Coulomb interaction, yet much stronger than the spin–orbit interaction. The atomic structures and spectra of a selected hydrogen atom are presented for a wide range of electron densities, temperatures, and electric and magnetic fields. The behavior of the energy and radiative transitions with respect to these interactions is analyzed in detail. The results obtained from the proposed approach are critically compared with other available results. The present study not only advances our understanding of the electronic structures and radiation characteristics of atomic systems in external fields but may also be relevant for astrophysics and laboratory experiments, especially on the solar corona, laser-produced plasmas, and so on.

Statistically Optimal Estimation of Signals in Modulation Spaces Using Gabor Frames

Time-frequency analysis deals with signals for which the underlying spectral characteristics change over time. The essential tool is the short-time Fourier transform, which localizes the Fourier transform in time by means of a window function. In a white noise model, we derive rate-optimal and adaptive estimators of signals in modulation spaces, which measure smoothness in terms of decay properties of the short-time Fourier transform. The estimators are based on series expansions by means of Gabor frames and on thresholding the coefficients. The minimax rates have interesting new features, and the derivation of the lower bounds requires the use of test functions which approximately localize both in time and in frequency. Simulations and applications to audio recordings illustrate the practical relevance of our methods. We also discuss the best <inline-formula> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula>-term approximation and the approximation of variational problems in modulation spaces by Gabor frame expansions.

Asymptotic properties of generalized D-solutions to the stationary axially symmetric Navier–Stokes equations

In this paper, we derive asymptotic properties of both the velocity and the vorticity fields to the 3-dimensional axially symmetric Navier–Stokes equations at infinity under the generalized D-solution assumption [Formula: see text] for [Formula: see text]. We do not impose any zero or non-zero constant vector asymptotic assumption to the solution at infinity. Our results generalize those in [H. Choe and B. Jin, Asymptotic properties of axis-symmetric D-solutions of the Navier–Stokes equations, J. Math. Fluid Mech. 11(2) (2009) 208–232; S. Weng, Decay properties of axially symmetric D-solutions to the steady Navier–Stokes equations, J. Math. Fluid Mech. 20(1) (2018) 7–25; B. Carrillo, X. Pan and Q. S. Zhang, Decay and vanishing of some axially symmetric D-solutions of the Navier–Stokes equations, J. Funct. Anal. 279(1) (2020) 108504], where the authors focused on the case [Formula: see text] and the velocity field approaches zero at infinity. Meanwhile, when [Formula: see text] and the velocity field approaches zero at infinity, our results coincide with the results in [H. Choe and B. Jin, Asymptotic properties of axis-symmetric D-solutions of the Navier–Stokes equations, J. Math. Fluid Mech. 11(2) (2009) 208–232; S. Weng, Decay properties of axially symmetric D-solutions to the steady Navier–Stokes equations, J. Math. Fluid Mech. 20(1) (2018) 7–25; B. Carrillo, X. Pan and Q. S. Zhang, Decay and vanishing of some axially symmetric D-solutions of the Navier–Stokes equations, J. Funct. Anal. 279(1) (2020) 108504].

Positivity-preserving and energy-dissipative finite difference schemes for the Fokker–Planck and Keller–Segel equations

Abstract In this work we introduce semi-implicit or implicit finite difference schemes for the continuity equation with a gradient flow structure. Examples of such equations include the linear Fokker–Planck equation and the Keller–Segel equations. The two proposed schemes are first-order accurate in time, explicitly solvable, and second-order and fourth-order accurate in space, which are obtained via finite difference implementation of the classical continuous finite element method. The fully discrete schemes are proved to be positivity preserving and energy dissipative: the second-order scheme can achieve so unconditionally while the fourth-order scheme only requires a mild time step and mesh size constraint. In particular, the fourth-order scheme is the first high order spatial discretization that can achieve both positivity and energy decay properties, which is suitable for long time simulation and to obtain accurate steady state solutions.

Strong decays of multistrangeness baryon resonances in the quark model

Decay properties of multistrangeness $\mathrm{\ensuremath{\Xi}}$ and $\mathrm{\ensuremath{\Omega}}$ baryon resonances are investigated within the constituent quark model by including relativistic corrections. The strong decay widths of various $\mathrm{\ensuremath{\Xi}}$ and $\mathrm{\ensuremath{\Omega}}$ resonances are computed and tested for internal quark configurations to pin down their spin-parity (${J}^{P}$) quantum numbers and internal structures. We found that the Roper-like resonances in the multistrangeness sector have large decay widths bearing resemblances to their siblings in light and heavy baryon sectors. In addition, we obtained the decay ratio for the $\mathrm{\ensuremath{\Omega}}(2012)$ as $\mathrm{\ensuremath{\Gamma}}(\mathrm{\ensuremath{\Omega}}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Xi}}\overline{K}\ensuremath{\pi})/\mathrm{\ensuremath{\Gamma}}(\mathrm{\ensuremath{\Omega}}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Xi}}\overline{K})=4.5%$, which is consistent with the experimental data when ${J}^{P}=3/{2}^{\ensuremath{-}}$ is assigned. This observation holds the possibility that the $\mathrm{\ensuremath{\Omega}}(2012)$ could naturally be explained as a three-quark state in the quark model. The decays of other low-lying $\mathrm{\ensuremath{\Xi}}$ and $\mathrm{\ensuremath{\Omega}}$ resonances are systematically analyzed, which would be useful to unveil the structure of these resonances in future experiments.