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Atoms, Volume 13, Issue 5 (May 2025) – 9 articles

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13 pages, 899 KiB  
Article
Quantification of Plutonium and Americium in Environmental Matrices Using Accelerator Mass Spectrometry
by Elena Moroianu, Iuliana Stanciu, Doru Pacesila, Andreea Dima, Oana Gaza and Daniel Vasile Mosu
Atoms 2025, 13(5), 45; https://doi.org/10.3390/atoms13050045 - 21 May 2025
Abstract
This study focused on the measurement of anthropogenic radionuclides such as americium (Am) and plutonium (Pu) in environmental samples. Plutonium isotopes, particularly Pu239, Pu240, and Pu241, originated from nuclear weapons testing, nuclear power plants, and accidents like [...] Read more.
This study focused on the measurement of anthropogenic radionuclides such as americium (Am) and plutonium (Pu) in environmental samples. Plutonium isotopes, particularly Pu239, Pu240, and Pu241, originated from nuclear weapons testing, nuclear power plants, and accidents like Chernobyl and Fukushima Daiichi. Accurate measurement of these isotopes, considering their half-lives and trace concentrations, provides critical information about their persistence and environmental transport. Using the 1 MV Tandetron accelerator, we expanded the measurement capabilities to include Pu241, Am241. Chemical separation of these isotopes was achieved through ion chromatography, employing reference isotopes Pu242 and Am243 for method validation. Certified reference materials, including IAEA-410 (Bikini Atoll sediment) and Sample 05, were analyzed to ensure accuracy. We validated the Am241/Am243 ratio in an Am standard (IFIN-STD-Am, our laboratory produced standard for Am), achieving a measured value of 0.158 at·at−1 (3%), in good agreement with the nominal value of 0.154 at·at−1. Additionally, we determined the (241Pu + Am241)/242Pu ratio in the ColPuS standard to be equal to 0.029 at ·at−1 (7%). These results demonstrate the potential of AMS for improved detection of actinides at low concentrations and contribute to understanding the behavior of Pu and Am isotopes. Full article
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11 pages, 6956 KiB  
Article
UK APAP R-Matrix Electron-Impact Excitation Cross-Sections for Modelling Laboratory and Astrophysical Plasma
by Giulio Del Zanna, Guiyun Liang, Junjie Mao and Nigel R. Badnell
Atoms 2025, 13(5), 44; https://doi.org/10.3390/atoms13050044 - 14 May 2025
Viewed by 143
Abstract
Systematic R-matrix calculations of electron-impact excitation for ions of astrophysical interest have been performed since 2007 for many iso-electronic sequences as part of the UK Atomic Process for Astrophysical Plasma (APAP) network. Rate coefficients for Maxwellian electron distributions have been provided and used [...] Read more.
Systematic R-matrix calculations of electron-impact excitation for ions of astrophysical interest have been performed since 2007 for many iso-electronic sequences as part of the UK Atomic Process for Astrophysical Plasma (APAP) network. Rate coefficients for Maxwellian electron distributions have been provided and used extensively in the literature and many databases for astrophysics. Here, we provide averaged collision strengths to be used to model plasma where electrons are non-Maxwellian, which often occurs in laboratory and astrophysical plasma. We also provide many new Maxwellian-averaged collision strengths, which include important corrections to the published values. Recently, we made available the H- and He-like collision strengths. Here, we provide data for ions of the Li-, Be-, B-, C-, N-, O-, Ne-, Na-, and Mg-like sequences. Full article
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14 pages, 1754 KiB  
Article
The Single-Active-Electron Approximation with Angular-Momentum-Dependent Potentials: Application to the Helium Atom
by Juan Carlos del Valle and Klaus Bartschat
Atoms 2025, 13(5), 43; https://doi.org/10.3390/atoms13050043 - 14 May 2025
Viewed by 138
Abstract
We discuss an extension of the Single-Active-Electron (SAE) approximation in atoms by allowing the model potential to depend on the angular-momentum quantum number . We refer to this extension as the -SAE approximation. The main ideas behind -SAE are illustrated [...] Read more.
We discuss an extension of the Single-Active-Electron (SAE) approximation in atoms by allowing the model potential to depend on the angular-momentum quantum number . We refer to this extension as the -SAE approximation. The main ideas behind -SAE are illustrated using the helium atom as a benchmark system. We show that introducing -dependent potentials improves the accuracy of key quantities in atomic structure computed from the Time-Independent Schrödinger Equation (TISE), including energies, oscillator strengths, and static and dynamic polarizabilities, compared to the standard SAE approach. Additionally, we demonstrate that the -SAE approximation is suitable for quantum simulations of light−atom interactions described by the Time-Dependent Schrödinger Equation (TDSE). As an illustration, we simulate High-order Harmonic Generation (HHG) and the three-sideband (3SB) version of the Reconstruction of Attosecond Beating by Interference of Two-photon Transitions (RABBITT) technique, achieving enhanced accuracy comparable to that obtained in all-electron calculations. One of the main advantages of the -SAE approach is that existing SAE codes can be easily adapted to handle -dependent potentials without any additional computational cost. Full article
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17 pages, 2106 KiB  
Article
Informational Entropy Analysis of Artificial Helium Atoms
by Marcilio N. Guimarães, Rafael N. Cordeiro, Wallas S. Nascimento and Frederico V. Prudente
Atoms 2025, 13(5), 42; https://doi.org/10.3390/atoms13050042 - 12 May 2025
Viewed by 108
Abstract
We use the Shannon informational entropies as a tool to study the artificial helium atom, namely, two electrons confined in a quantum dot. We adopt configurations with spherical and cylindrical symmetries for the physical system of interest. Using the informational quantities, we analyze [...] Read more.
We use the Shannon informational entropies as a tool to study the artificial helium atom, namely, two electrons confined in a quantum dot. We adopt configurations with spherical and cylindrical symmetries for the physical system of interest. Using the informational quantities, we analyze the effects of electronic confinement, we validate the entropic uncertainty relation, we identify that the Coulomb interaction potential between the electrons is no longer important for strong confinements, and we indicate/predict the avoided crossing phenomena. Finally, we carried out a density function analysis. When available, the results are compared with those in the literature. Full article
(This article belongs to the Section Atom Based Quantum Technology)
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15 pages, 1508 KiB  
Article
Neutron Cross-Section Uncertainty and Reactivity Analysis in MOX and Metal Fuels for Sodium-Cooled Fast Reactor
by Oyeon Kum
Atoms 2025, 13(5), 41; https://doi.org/10.3390/atoms13050041 - 6 May 2025
Viewed by 173
Abstract
This study presents a comprehensive uncertainty and sensitivity analysis of the effective neutron multiplication factor (keff) in a large-scale sodium-cooled fast reactor (SFR) modeled after the European Sodium Fast Reactor. Utilizing the Serpent Monte Carlo code and the ENDF/B-VII.1 cross-section [...] Read more.
This study presents a comprehensive uncertainty and sensitivity analysis of the effective neutron multiplication factor (keff) in a large-scale sodium-cooled fast reactor (SFR) modeled after the European Sodium Fast Reactor. Utilizing the Serpent Monte Carlo code and the ENDF/B-VII.1 cross-section library, this research investigates the impact of cross-section perturbations in key isotopes (235U, 238U, and 239Pu for both mixed oxide (MOX) and metal fuels. Particular focus is placed on the capture, fission, and inelastic scattering reactions, as well as the effects of fuel temperature on reactivity through Doppler broadening. The findings reveal that reactivity in MOX fuel is highly sensitive to the fission cross sections of fissile isotopes (239Pu and 238U, while capture and inelastic scattering reactions in fertile isotopes such as 238U play a significant role in reducing reactivity, enhancing neutron economy. Additionally, this study highlights that metal fuel configurations generally achieve a higher (keff) compared to MOX, attributed to their higher fissile atom density and favorable thermal properties. These results underscore the importance of accurate nuclear data libraries to minimize uncertainties in criticality evaluations, and they provide a foundation for optimizing fuel compositions and refining reactor control strategies. The insights gained from this analysis can contribute to the development of safer and more efficient next-generation SFR designs, ultimately improving operational margins and reactor performance. Full article
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6 pages, 294 KiB  
Communication
Triple-Differential Cross-Section Calculations for Positron Impact Ionization of Argon
by Radu I. Campeanu, Zsuzsánna Bálint and Ladislau Nagy
Atoms 2025, 13(5), 40; https://doi.org/10.3390/atoms13050040 - 4 May 2025
Viewed by 167
Abstract
Triple-differential cross-sections for the positron impact ionization of argon were calculated using a distorted-wave Born approximation (DWBA) convoluted to the experimental uncertainties. In almost all of the cases studied, our results agree well with the positions and heights of the experimental peaks. Full article
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20 pages, 1096 KiB  
Article
Elastic e-Atom Scattering Using Multi-Configuration Dirac–Fock Partial Wave Analysis
by R. Aiswarya and Jobin Jose
Atoms 2025, 13(5), 39; https://doi.org/10.3390/atoms13050039 - 30 Apr 2025
Viewed by 139
Abstract
A novel scattering formalism, the multi-configuration Dirac–Fock partial wave analysis (MCDF-PWA), is presented in this study. This approach extends the conventional Dirac partial wave analysis by incorporating multiple atomic configurations of the target scatterer. The newly formulated methodology is employed to compute the [...] Read more.
A novel scattering formalism, the multi-configuration Dirac–Fock partial wave analysis (MCDF-PWA), is presented in this study. This approach extends the conventional Dirac partial wave analysis by incorporating multiple atomic configurations of the target scatterer. The newly formulated methodology is employed to compute the cross-sections in elastic e-atom scattering. The analysis is performed for a few atomic targets like Mg, Ca, and Ba. Full article
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13 pages, 1058 KiB  
Article
A Novel Approach to Calculate the Range of High-Energy Charged Particles Within a Medium
by Ioannis Psychogios, Stylianos Vasileios Kontomaris, Anna Malamou and Andreas Stylianou
Atoms 2025, 13(5), 38; https://doi.org/10.3390/atoms13050038 - 27 Apr 2025
Viewed by 170
Abstract
The determination of energy loss of charged particles as they pass through a medium and consequently the calculation of their range within the medium are of tremendous importance in various areas of physics from both theoretical and practical perspectives. Previous works have derived [...] Read more.
The determination of energy loss of charged particles as they pass through a medium and consequently the calculation of their range within the medium are of tremendous importance in various areas of physics from both theoretical and practical perspectives. Previous works have derived approximate equations regarding the range of ions within a medium, focusing on providing simple solutions for practitioners in the radiotherapy field that do not require significant computational cost, unlike traditional Monte Carlo methods. These solutions focus on radiotherapy and are limited to specific ions’ initial speeds, which should be up to 0.65c (where c is the speed of light in vacuum). In this paper, solutions for significantly larger initial velocities are explored. A new analytical equation for determining the range of charged particles within a medium for initial velocities between 0.6c and 0.9c is presented. This equation provides excellent results when compared to the accurate numerical solution. Beyond its theoretical and mathematical interest, this solution is also reliable for radiotherapy applications. It provides excellent results for protons with initial energies between 200 MeV and 350 MeV and has the major advantage of being expressed in terms of elementary functions, making its use more straightforward compared to other approaches. Full article
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15 pages, 570 KiB  
Article
Electron and Positron Collision with Plasma Wall Coating Elements
by Balajee R, Yurekha S.P., Snigdha Sharma and Dhanoj Gupta
Atoms 2025, 13(5), 37; https://doi.org/10.3390/atoms13050037 - 26 Apr 2025
Viewed by 232
Abstract
The investigation of integral elastic cross-section (ICS), momentum transfer cross-section (MTCS), viscosity cross-section (VCS), absorption cross-section (ABSCS), and total cross-section (TCS) of atoms by electron (e) and positron (e+) impact is very crucial and essential for understanding [...] Read more.
The investigation of integral elastic cross-section (ICS), momentum transfer cross-section (MTCS), viscosity cross-section (VCS), absorption cross-section (ABSCS), and total cross-section (TCS) of atoms by electron (e) and positron (e+) impact is very crucial and essential for understanding fundamental atomic processes and their applications in various fields such as plasma physics, molecular physics, and astrophysics. This study investigates and analyses the ICS, MTCS, VCS, ABSCS, and TCS of the atoms, Li, Be, B, Ti, and W, over a wide energy range. By employing the computational Optical Potential Method (OPM) and quantum scattering integrated in a computational package, ELSEPA (Elastic scattering of electrons and positrons by atoms, positive ions and molecules), the cross-sections of atoms by electron and positron impact are calculated. The present results shows good agreement with all the experimental and theoretical data available in the literature. The obtained cross-sections may facilitate the development of accurate models for plasma simulations and fusion research. Full article
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