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17 pages, 5583 KiB

Open AccessArticle

Interaction of Protons with Noble-Gas Atoms: Total and Differential Cross Sections

by Musab Al-Ajaleen and Károly Tőkési

Atoms 2024, 12(5), 28; https://doi.org/10.3390/atoms12050028 - 7 May 2024

Cited by 2 | Viewed by 1563

We present a classical treatment of the ionization and electron-capture processes in the interaction of protons with neutral noble-gas atoms, namely, Ne, Ar, Kr, and Xe. We used a three-body classical-trajectory Monte Carlo (CTMC) method to calculate the total (TCS) and differential (DCS) cross sections of single-electron processes. The Garvey-type model potential was employed in the CTMC model to describe the collision between the projectile and the target, accounting for the screening effect of the inactive electrons. The TCSs are evaluated for impact energies in the energy range between 0.2 keV and 50 MeV for a number of sub-shells of the targets. The ionization DCS are evaluated for an impact energy of 35 keV, focusing on the outer sub-shells only. We found that our ionization and electron-capture TCSs are in very good agreement with the previous theoretical and experimental data for all targets. Moreover, we presented single (SDCS)- and double (DDCS)-differential cross sections as a function of the energy and ejection angle of the ionized electron for all collision systems. Full article

(This article belongs to the Section Atomic, Molecular and Nuclear Spectroscopy and Collisions)

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9 pages, 1650 KiB

Open AccessCommunication

Ionization of Hydrogen Atom by Proton Impact—How Accurate Is the Ionization Cross Section?

by Károly Tőkési and Saleh Alassaf

Atoms 2023, 11(9), 122; https://doi.org/10.3390/atoms11090122 - 15 Sep 2023

Viewed by 2059

Abstract

For the control of fusion reactors, we need to accurately know all the possible reactions and collisional cross sections. Although large-scale trials have been performed over the last decades to obtain this data, many basic atomic and molecular cross section data are missing and the accuracy of the available cross sections need to be checked. Using the available measured cross sections and theoretical predictions of hydrogen atom ionization by proton impact, critical analysis of the data is presented. Moreover, we also present our recent classical results based on the standard classical trajectory Monte Carlo (CTMC) and quasi-classical trajectory Monte Carlo (C-QCTMC) models. According to our model calculations and comparison with the experimental data, recom-mended cross sections for ionization of hydrogen were presented in a wide range of pro-jectile impact energies. We found that, while in the low energy region, the experimental cross sections are very close to the C-QCTMC results, at higher energies, they are close to the results of our standard CTMC results. Full article

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7 pages, 685 KiB

Open AccessArticle

nl-Selective Classical Charge-Exchange Cross Sections in Be⁴⁺ and Ground State Hydrogen Atom Collisions

by Iman Ziaeian and Károly Tőkési

Atoms 2022, 10(3), 90; https://doi.org/10.3390/atoms10030090 - 9 Sep 2022

Cited by 2 | Viewed by 2037

Abstract

Charge-exchange cross sections in Be⁴⁺ + H(1s) collisions are calculated using the three-body classical trajectory Monte Carlo method (CTMC) and the quasi-classical trajectory Monte Carlo method of Kirschbaum and Wilets (QCTMC) for impact energies between 10 keV/amu and 300 keV/amu. We present charge-exchange cross sections in the projectile n = 2 and nl = 2s, 2p states. Our results are compared with the previous quantum-mechanical approaches. We found that the QCTMC model is a powerful classical model to describe the state-selective charge-exchange cross sections at lower impact energies and the QCTMC results are in good agreement with previous observations. Full article

(This article belongs to the Special Issue Interaction of Electrons with Atoms, Molecules and Surfaces)

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11 pages, 2397 KiB

Open AccessArticle

Interaction of Be⁴⁺ and Ground State Hydrogen Atom—Classical Treatment of the Collision

by I. Ziaeian and K. Tőkési

Atoms 2020, 8(2), 27; https://doi.org/10.3390/atoms8020027 - 3 Jun 2020

Cited by 18 | Viewed by 3684

Abstract

The interaction between Be⁴⁺ and hydrogen atom is studied using the three-body classical trajectory Monte Carlo method (CTMC) and the quasiclassical trajectory Monte Carlo method of Kirschbaum and Wilets (QTMC-KW). We present total cross sections for target ionization, target excitation, and charge exchange to the projectile bound states. Calculations are carried out in the projectile energy range between 10 and 1000 keV/au, relevant to the interest of fusion research when the target hydrogen atom is in the ground state. Our results are compared with previous theoretical results. We found that the classical treatment describes reasonably well the cross sections for various final channels. Moreover, we show that the calculations by the QTMC-KW model significantly improve the obtained cross sections. Full article

(This article belongs to the Special Issue Accelerator-Based Atomic Physics: Fast Ion–Atom and Ion–Molecule Collisions)

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9 pages, 2464 KiB

Open AccessArticle

Doubly and Triply Differential Cross Sections for Single Ionization of He by Fast Au⁵³⁺ Using a Multi-Body Quasiclassical Model

by François Frémont

Atoms 2020, 8(2), 19; https://doi.org/10.3390/atoms8020019 - 6 May 2020

Cited by 1 | Viewed by 2489

Abstract

A multi-body multi-center quasiclassical model was used to determine doubly- and triply-differential cross sections following single ionization in 3.6 MeV/amu Au⁵³⁺ + He collisions. The present model improved recent calculations, in which free electrons were added in the collision to reproduce, at least qualitatively, the experimental binary peak. In the present calculations, the electrons, that were assumed to originate from the collisions of Au⁵³⁺ with surfaces before colliding with the He target, were now considered to be in the field of the projectile, with nearly the same velocity. The agreement between the calculations and the experiment was improved, for both the doubly- and the triply-differential cross sections and was better than previous calculations based on quantum mechanics. Full article

(This article belongs to the Special Issue Accelerator-Based Atomic Physics: Fast Ion–Atom and Ion–Molecule Collisions)

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9 pages, 2458 KiB

Open AccessArticle

Transverse Momentum Transfer Distributions Following Single Ionization in 3.6 MeV/amu Au⁵³⁺ + He Collisions: A 4-Body Classical Treatment

by François Frémont

Atoms 2018, 6(4), 68; https://doi.org/10.3390/atoms6040068 - 3 Dec 2018

Cited by 4 | Viewed by 3054

Abstract

A four-body classical model based on the resolution of Hamilton equations of motion was used here to determine and analyze ionization doubly-differential cross sections following 3.6 MeV/amu Au⁵³⁺ + He collisions. Our calculation was not able to reproduce the binary peaks experimentally observed in the transverse momentum distributions for electron emission energies larger than 10 eV. Surprisingly, by introducing a large number of free or quasi-free electrons that followed the projectile at the same velocity, the agreement between the experiment and our calculation was improved, since our model reproduced, at least qualitatively, the experimental binary peaks. The origin of the presence of such electrons is discussed. Full article

(This article belongs to the Special Issue Recent Advances in Ion-Impact Atomic Collisions: Experiment, Theory and Applications)

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