Atoms

Research

8 pages, 366 KiB

Open AccessCommunication

g Factor of Few-Electron Highly Charged Ions

by Dmitry A. Glazov, Dmitrii V. Zinenko, Valentin A. Agababaev, Artyom D. Moshkin, Elizaveta V. Tryapitsyna, Anna M. Volchkova and Andrey V. Volotka

Atoms 2023, 11(9), 119; https://doi.org/10.3390/atoms11090119 - 8 Sep 2023

Cited by 1 | Viewed by 1733

Abstract

The current status of the theoretical investigation of the bound-electron g factor in lithium-like and boron-like highly charged ions is reported. Some tension between the several theoretical values and measurements is discussed. Then, prospects for future investigations are briefly reviewed. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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13 pages, 4448 KiB

Open AccessArticle

Theoretical Investigation of Electron–Ion Recombination Process of Mg-like Gold

by Luyou Xie, Wenliang He, Shengbo Niu, Jinglin Rui, Yulong Ma and Chenzhong Dong

Atoms 2023, 11(5), 76; https://doi.org/10.3390/atoms11050076 - 23 Apr 2023

Viewed by 1626

Abstract

The L-shell dielectronic and trielectronic recombinations of highly charged Mg-like gold ions (Au⁶⁷⁺) in the ground state 2s²2p⁶3s^2 1S₀ have been studied systematically. The recombination cross-sections and rate coefficients are carefully calculated [...] Read more.

The L-shell dielectronic and trielectronic recombinations of highly charged Mg-like gold ions (Au⁶⁷⁺) in the ground state 2s²2p⁶3s^2 1S₀ have been studied systematically. The recombination cross-sections and rate coefficients are carefully calculated for ∆n = 1 (2s/2p → 3l) transitions using a flexible atomic code based on the relativistic configuration interaction method and considering the Breit and QED corrections. Detailed resonance energies and resonance strengths are presented for the stronger resonances of the LMn (n = 3–12) series. It is found that the contributions of the trielectronic recombination to the total cross-section is about 13.75%, which cannot be neglected. For convenience of application, the plasma rate coefficients are also calculated and fitted to a semiempirical formula, and in the calculations, the contributions from the higher excited resonance groups n ≥ 13 are evaluated by an extrapolation method, which is about 2.93% of the total rate coefficient. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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8 pages, 510 KiB

Open AccessCommunication

Shape and Satellite Studies of Highly Charged Ions X-ray Spectra Using Bayesian Methods

by Martino Trassinelli

Atoms 2023, 11(4), 64; https://doi.org/10.3390/atoms11040064 - 1 Apr 2023

Cited by 1 | Viewed by 1340

Abstract

High-accuracy spectroscopy commonly requires dedicated investigation into the choice of spectral line modelling to avoid the introduction of unwanted systematic errors. For such a kind of problem, the analysis of

χ^{2}

and likelihood are normally implemented to choose among models. However, these [...] Read more.

High-accuracy spectroscopy commonly requires dedicated investigation into the choice of spectral line modelling to avoid the introduction of unwanted systematic errors. For such a kind of problem, the analysis of

χ^{2}

and likelihood are normally implemented to choose among models. However, these standard practices are affected by several problems and, in the first place, they are useless if there is no clear indication in favour of a specific model. Such issues are solved by Bayesian statistics, in the context of which a probability can be assigned to different hypotheses, i.e., models, from the analysis of the same set of data. Model probabilities are obtained from the integration of the likelihood function over the model parameter space with the evaluation of the so-called Bayesian evidence. Here, some practical applications are presented within the context of the analysis of recent high-accuracy X-ray spectroscopy data of highly charged uranium ion transitions. The method to determine the most plausible profile is discussed in detail. The study of the possible presence of satellite peaks is also presented. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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8 pages, 710 KiB

Open AccessCommunication

Identification of Visible Lines in Pm-like W¹³⁺

by Priti, Kota Inadome, Mayuko Funabashi, Nobuyuki Nakamura, Hiroyuki A. Sakaue, Izumi Murakami and Daiji Kato

Atoms 2023, 11(3), 57; https://doi.org/10.3390/atoms11030057 - 13 Mar 2023

Cited by 3 | Viewed by 1673

Abstract

To provide spectroscopic data for W

^{13 +}

, the present work is focused on the analysis of spectra observed in the visible range, using a compact electron beam ion trap (CoBIT). Line identification is done by using a collisional radiative model, along [...] Read more.

To provide spectroscopic data for W

^{13 +}

, the present work is focused on the analysis of spectra observed in the visible range, using a compact electron beam ion trap (CoBIT). Line identification is done by using a collisional radiative model, along with sophisticated structure calculations from FAC and GRASP2018. Most of the identified lines belong to magnetic dipole (M1) transitions between the levels of the

4 f^{12} 5 p^{1}

and

4 f^{13}

configurations. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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8 pages, 475 KiB

Open AccessCommunication

Electron Emission Cross Section from Methane under 250 keV Proton Impact

by Debasmita Chakraborty, László Gulyás and Lokesh C. Tribedi

Atoms 2023, 11(3), 49; https://doi.org/10.3390/atoms11030049 - 4 Mar 2023

Viewed by 1396

Abstract

We measure double differential cross sections (DDCS) of electrons emitted from CH₄ molecules in collisions with 250 keV protons. The projectile ions are obtained from a 400 kV electron cyclotron resonance-based ion accelerator (ECRIA). We study the energy and angular distributions of [...] Read more.

We measure double differential cross sections (DDCS) of electrons emitted from CH₄ molecules in collisions with 250 keV protons. The projectile ions are obtained from a 400 kV electron cyclotron resonance-based ion accelerator (ECRIA). We study the energy and angular distributions of the electron DDCS. The observed double and single differential and the total cross section are compared with the state-of-the-art continuum distorted wave eikonal initial state (CDW-EIS) model predictions. Two different approaches are used considering the different target descriptions: complete neglect of differential overlap (CNDO) and molecular orbital (MO) approximations. The MO model uses two different scaling parameters (d = 0.7 and 1.0). In the energy distribution of the DDCS, the carbon KLL Auger line is also observed at 240 eV. The single differential cross section (SDCS) and total cross section (TCS) are derived. Both the MO-based CDW-EIS models are in good agreement with the experimental results; however, the CNDO approach overestimates the data. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 400 KiB

Open AccessArticle

Background and Blended Spectral Line Reduction in Precision Spectroscopy of EUV and X-ray Transitions in Highly Charged Ions

by Adam Hosier, Dipti, Yang Yang, Paul Szypryt, Grant P. Mondeel, Aung Naing, Joseph N. Tan, Roshani Silwal, Galen O’Neil, Alain Lapierre, Steven A. Blundell, John D. Gillaspy, Gerald Gwinner, Antonio C. C. Villari, Yuri Ralchenko and Endre Takacs

Atoms 2023, 11(3), 48; https://doi.org/10.3390/atoms11030048 - 3 Mar 2023

Viewed by 1802

Abstract

Extreme ultraviolet spectra of Na-like and Mg-like Os and Ir were recorded at the National Institute of Standards and Technology using a grazing incidence spectrometer. We report a method in EBIT spectral analysis that reduces signals from contaminant lines of known or unknown [...] Read more.

Extreme ultraviolet spectra of Na-like and Mg-like Os and Ir were recorded at the National Institute of Standards and Technology using a grazing incidence spectrometer. We report a method in EBIT spectral analysis that reduces signals from contaminant lines of known or unknown origin. We utilize similar ion charge distributions of heavy highly charged ions that create similar potentials for lighter contaminating background elements. First-order approximations to ion distributions are presented to demonstrate differences between impurity elements with and without heavy ions present. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 4182 KiB

Open AccessArticle

Determination of Electron Beam Energy in Measuring the Electron-Impact Ionization Cross Section of He-like Fe²⁴⁺

by Yang Yang, Dipti, Amy Gall, Galen O’Neil, Paul Szypryt, Adam Hosier, Adam Foster, Aung Naing, Joseph N. Tan, David R. Schultz, Randall Smith, Nancy Brickhouse, Yuri Ralchenko and Endre Takacs

Atoms 2023, 11(3), 44; https://doi.org/10.3390/atoms11030044 - 1 Mar 2023

Viewed by 1923

Abstract

In an effort to measure electron-impact ionization (EII) cross-sections of He-like

F e^{24 +}

at the electron beam ion trap (EBIT) facility of the National Institute of Standards and Technology (NIST), we have experimentally determined the corrections to the nominal beam energy [...] Read more.

In an effort to measure electron-impact ionization (EII) cross-sections of He-like

F e^{24 +}

at the electron beam ion trap (EBIT) facility of the National Institute of Standards and Technology (NIST), we have experimentally determined the corrections to the nominal beam energy determined by the voltages applied to the EBIT. High-resolution X-ray spectra were recorded at nominal electron beam energies between 6660 eV and 6750 eV using X-ray microcalorimetry based upon an array of 192 transition-edge sensors (TES). A large-scale collisional-radiative simulation of the non-Maxwellian EBIT plasma using relevant atomic data calculated with Flexible Atomic Code allowed us to determine the space-charge correction due to the electron beam including the neutralization factor by the ion cloud of the EBIT. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 784 KiB

Open AccessArticle

Analysis of E3 Transitions in Ag-like High-Z Ions Observed with the NIST EBIT

by Endre Takacs, Dipti, David S. La Mantia, Yang Yang, Adam Hosier, Aung Naing, Paul Szypryt, Hunter Staiger, Joseph N. Tan and Yuri Ralchenko

Atoms 2023, 11(3), 43; https://doi.org/10.3390/atoms11030043 - 1 Mar 2023

Cited by 2 | Viewed by 1685

Abstract

We report measurements and identification of the E3 4f

_{7 / 2, 5 / 2}

-5s

_{1 / 2}

transitions and E1 allowed transitions in Ag-like W (Z = 74), Re (Z = 75), and Ir (Z = 77). The spectra were [...] Read more.

We report measurements and identification of the E3 4f

_{7 / 2, 5 / 2}

-5s

_{1 / 2}

transitions and E1 allowed transitions in Ag-like W (Z = 74), Re (Z = 75), and Ir (Z = 77). The spectra were recorded at the NIST EBIT using a grazing-incidence EUV spectrometer. The present measured wavelengths and theoretical predictions using GRASP2K calculations confirm previous observations of the same E3 transitions in Ag-like W. Our collisional–radiative model using the NOMAD code offers an insight into the population kinematics for Ag-like ions of heavy elements. We discuss the observed spectra and comparisons of the measured and simulated spectral lines. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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6 pages, 713 KiB

Open AccessCommunication

Charge Exchange Spectroscopy of Multiply Charged Erbium Ions

by Yuki Nishimura, Saki Imaizumi, Hajime Tanuma, Nobuyuki Nakamura, Yuichiro Sekiguchi, Shinya Wanajo, Hiroyuki A. Sakaue, Daiji Kato, Izumi Murakami, Masaomi Tanaka and Gediminas Gaigalas

Atoms 2023, 11(2), 40; https://doi.org/10.3390/atoms11020040 - 15 Feb 2023

Viewed by 2017

Abstract

The origin of heavier elements than iron is still under discussion, and recent studies suggest that the contribution of the r-process in neutron star mergers is dominant. Future modeling of such processes will require a huge amount of spectroscopic data on multiply charged [...] Read more.

The origin of heavier elements than iron is still under discussion, and recent studies suggest that the contribution of the r-process in neutron star mergers is dominant. Future modeling of such processes will require a huge amount of spectroscopic data on multiply charged ions of heavy elements. However, these experimental data are extremely scarce for heavy elements. In this work, we have performed the measurements of charge exchange spectroscopy for multiply charged Er ions in the visible light range. We report observed emission lines from multiply charged Er ions and their identification based on theoretical estimates. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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6 pages, 3503 KiB

Open AccessCommunication

XUV Fluorescence Detection of Laser-Cooled Stored Relativistic Ions

by Ken Ueberholz, Lars Bozyk, Michael Bussmann, Noah Eizenhöfer, Volker Hannen, Max Horst, Daniel Kiefer, Nils Kiefer, Sebastian Klammes, Thomas Kühl, Benedikt Langfeld, Markus Loeser, Xinwen Ma, Wilfried Nörtershäuser, Rodolfo Sánchez, Ulrich Schramm, Mathias Siebold, Peter Spiller, Markus Steck, Thomas Stöhlker, Thomas Walther, Hanbing Wang, Christian Weinheimer, Weiqiang Wen and Danyal Winters Show full author list Hide full author list

Atoms 2023, 11(2), 39; https://doi.org/10.3390/atoms11020039 - 13 Feb 2023

Cited by 1 | Viewed by 1654

Abstract

An improved moveable in vacuo XUV fluorescence detection system was employed for the laser cooling of bunched relativistic (

β

= 0.47) carbon ions at the Experimental Storage Ring (ESR) of GSI Helmholtzzentrum Darmstadt, Germany. Strongly Doppler boosted XUV fluorescence (∼90 nm) was [...] Read more.

An improved moveable in vacuo XUV fluorescence detection system was employed for the laser cooling of bunched relativistic (

β

= 0.47) carbon ions at the Experimental Storage Ring (ESR) of GSI Helmholtzzentrum Darmstadt, Germany. Strongly Doppler boosted XUV fluorescence (∼90 nm) was emitted from the ions in a forward light cone after laser excitation of the 2s–2p transition (∼155 nm) by a new tunable pulsed UV laser system (257 nm). It was shown that the detected fluorescence strongly depends on the position of the detector around the bunched ion beam and on the delay (∼ns) between the ion bunches and the laser pulses. In addition, the fluorescence information could be directly combined with the revolution frequencies of the ions (and their longitudinal momentum spread), which were recorded using the Schottky resonator at the ESR. These fluorescence detection features are required for future laser cooling experiments at highly relativistic energies (up to

γ \sim

13) and high intensities (up to

10^{11}

particles) of ion beams in the new heavy ion synchrotron SIS100 at FAIR. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 911 KiB

Open AccessArticle

Methane Cluster Fragmentation by Fast Electron Impact

by Shuncheng Yan, Ruitian Zhang, Shaofeng Zhang and Xinwen Ma

Atoms 2023, 11(2), 35; https://doi.org/10.3390/atoms11020035 - 10 Feb 2023

Viewed by 1734

Abstract

We investigate the fragmentation of the CH₄ cluster by fast electron impact at stagnation pressures from 0.5 bar to 16 bar. By measuring the time of flight spectrum (TOF), two types of ions, including (CH₄)_n−1CH₅⁺ and [...] Read more.

We investigate the fragmentation of the CH₄ cluster by fast electron impact at stagnation pressures from 0.5 bar to 16 bar. By measuring the time of flight spectrum (TOF), two types of ions, including (CH₄)_n−1CH₅⁺ and (CH₄)_n−2(C₂H_m)⁺, are observed. In the 1D TOF spectrum, it is shown that for the stagnation pressure larger than 4 bar, the former ion is predominant for each n, similar to the previous experimental result. However, as the pressure decreases to 0.5 or 2 bar, the contribution of the C₂H_m⁺ ion is dominant over that of the CH₄CH₅⁺ ion. In the 2D coincident TOF spectrum, the above two patterns of ions are also distinguished, and the enhancement of C₂H_m⁺ is observed at 4 bar pressure. The phenomena appearing in 2D and 1D TOF spectra imply that the C₂H_m⁺ ion prefers to survive in a smaller cluster, while the stabilization of the protonated ion needs a more massive cluster environment. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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9 pages, 2107 KiB

Open AccessArticle

Probing the Fragmentation Pathways of an Argon Dimer in Slow Ion–Dimer Collisions

by Md Abul Kalam Azad Siddiki, Lokesh C. Tribedi and Deepankar Misra

Atoms 2023, 11(2), 34; https://doi.org/10.3390/atoms11020034 - 9 Feb 2023

Cited by 5 | Viewed by 1576

Abstract

We report the development of a supersonic jet assembly to study electron transfer collisions with atoms, molecules, and van der Waals clusters. A comparative study of Ar monomer and dimer cations is presented for different capture-associated channels with a 2.5 keV/u O²⁺ [...] Read more.

We report the development of a supersonic jet assembly to study electron transfer collisions with atoms, molecules, and van der Waals clusters. A comparative study of Ar monomer and dimer cations is presented for different capture-associated channels with a 2.5 keV/u O²⁺ projectile beam. For the Ar⁺ + Ar⁺ fragmentation channel, the interatomic relaxation channels are discussed. The vacancies of the dimer single site or double site show the dependence on capture mechanisms. In the Ar²⁺ + Ar⁺ fragmentation channel, double capture, in addition to the single ionization process, dominates. The orientation effect reflects the maximum yield at around 50 and 130 degrees, and angular distributions are nearly symmetric about the axis perpendicular to the dimer axis. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 251 KiB

Open AccessCommunication

Detailed Analysis of Spectra from Ga-like Ions of Heavy Elements Observed in High-Temperature Plasmas

by Chihiro Suzuki, Fumihiro Koike, Izumi Murakami, Daiji Kato, Naoki Tamura, Tetsutarou Oishi and Nobuyuki Nakamura

Atoms 2023, 11(2), 33; https://doi.org/10.3390/atoms11020033 - 7 Feb 2023

Viewed by 1524

Abstract

This study has systematically investigated the atomic number (Z) dependence of spectra from gallium-like (Ga-like) ions of heavy elements. We have mainly analyzed the experimental spectra recorded in high-temperature plasmas produced in the Large Helical Device (LHD) for various elements with [...] Read more.

This study has systematically investigated the atomic number (Z) dependence of spectra from gallium-like (Ga-like) ions of heavy elements. We have mainly analyzed the experimental spectra recorded in high-temperature plasmas produced in the Large Helical Device (LHD) for various elements with atomic numbers from 57 onward. The measured wavelengths are compared with theoretical values calculated with a multi-configuration Dirac Fock code. As a result, we have successfully obtained Z-dependent wavelengths of several prominent transitions of Ga-like ions, including a magnetic dipole (M1) transition. Many of them have been experimentally identified for the first time in this study. The present results manifest the significant effects of configuration interaction and spin–orbit interaction for highly charged heavy ions. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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9 pages, 1265 KiB

Open AccessArticle

Towards an Intrinsic Doppler Correction for X-ray Spectroscopy of Stored Ions at CRYRING@ESR

by Felix Martin Kröger, Günter Weber, Steffen Allgeier, Zoran Andelkovic, Sonja Bernitt, Alexander Borovik, Jr., Louis Duval, Andreas Fleischmann, Oliver Forstner, Marvin Friedrich, Jan Glorius, Alexandre Gumberidze, Christoph Hahn, Frank Herfurth, Daniel Hengstler, Marc Oliver Herdrich, Pierre-Michel Hillenbrand, Anton Kalinin, Markus Kiffer, Maximilian Kubullek, Patricia Kuntz, Michael Lestinsky, Bastian Löher, Esther Babette Menz, Tobias Over, Nikolaos Petridis, Philip Pfäfflein, Stefan Ringleb, Ragandeep Singh Sidhu, Uwe Spillmann, Sergiy Trotsenko, Andrzej Warczak, Binghui Zhu, Christian Enss and Thomas Stöhlker Show full author list Hide full author list

Atoms 2023, 11(2), 22; https://doi.org/10.3390/atoms11020022 - 28 Jan 2023

Cited by 2 | Viewed by 1768

Abstract

We report on a new experimental approach for the Doppler correction of X-rays emitted by heavy ions, using novel metallic magnetic calorimeter detectors which uniquely combine a high spectral resolution with a broad bandwidth acceptance. The measurement was carried out at the electron [...] Read more.

We report on a new experimental approach for the Doppler correction of X-rays emitted by heavy ions, using novel metallic magnetic calorimeter detectors which uniquely combine a high spectral resolution with a broad bandwidth acceptance. The measurement was carried out at the electron cooler of CRYRING@ESR at GSI, Darmstadt, Germany. The X-ray emission associated with the radiative recombination of cooler electrons and stored hydrogen-like uranium ions was investigated using two novel microcalorimeter detectors positioned under 0

^{\circ}

and 180

^{\circ}

with respect to the ion beam axis. This new experimental setup allowed the investigation of the region of the N, M → L transitions in helium-like uranium with a spectral resolution unmatched by previous studies using conventional semiconductor X-ray detectors. When assuming that the rest-frame energy of at least a few of the recorded transitions is well-known from theory or experiments, a precise measurement of the Doppler shifted line positions in the laboratory system can be used to determine the ion beam velocity using only spectral information. The spectral resolution achievable with microcalorimeter detectors should, for the first time, allow intrinsic Doppler correction to be performed for the precision X-ray spectroscopy of stored heavy ions. A comparison with data from a previous experiment at the ESR electron cooler, as well as the conventional method of conducting Doppler correction using electron cooler parameters, will be discussed. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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8 pages, 1811 KiB

Open AccessArticle

Electron Capture by Proton Beam in Collisions with Water Vapor

by Sanjeev Kumar Maurya, Abhijeet Bhogale and Lokesh C. Tribedi

Atoms 2023, 11(2), 21; https://doi.org/10.3390/atoms11020021 - 27 Jan 2023

Viewed by 1630

Abstract

In low energy ion-molecule collisions, electron capture is one of the most important channels. A new experimental setup was developed to study the electron capture process using low-energy ion beams extracted from an electron cyclotron resonance (ECR) plasma-based ion accelerator. Experiments were carried [...] Read more.

In low energy ion-molecule collisions, electron capture is one of the most important channels. A new experimental setup was developed to study the electron capture process using low-energy ion beams extracted from an electron cyclotron resonance (ECR) plasma-based ion accelerator. Experiments were carried out with the proton beam colliding with water vapor in the energy range of 70–300 keV. Capture events were detected using a position-sensitive detection system comprising micro channel plates (MCPs) and a delay line detector (DLD). These e-capture events can be a result of pure capture reactions as well as transfer ionization. The capture cross section was found to decrease sharply with the beam energy and agreed well with previous measurements. The setup was also used to detect the events that gave rise to the single and multiple e-capture (integrated over all recoil-ion charge states) of C⁴⁺ ions. The capture cross-sections for one, two, three, and four electrons were measured for 100 keV C⁴⁺ ions. The ratio of multielectron capture yield to that for single e-capture decreased with the number of captured electrons. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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8 pages, 1480 KiB

Open AccessArticle

X-ray Spectroscopy Based on Micro-Calorimeters at Internal Targets of Storage Rings

by Marc Oliver Herdrich, Daniel Hengstler, Andreas Fleischmann, Christian Enss, Alexandre Gumberidze, Pierre-Michel Hillenbrand, Paul Indelicato, Stephan Fritzsche and Thomas Stöhlker

Atoms 2023, 11(1), 13; https://doi.org/10.3390/atoms11010013 - 14 Jan 2023

Cited by 3 | Viewed by 1556

Abstract

With metallic-magnetic calorimeters (MMCs), promising detectors for high-precision X-ray spectrometry in atomic and fundamental physics experiments are available. In this work, we present a pilot experiment based on a maXs-30 type MMC-spectrometer for recording X-rays emitted in collisions of lithium-like uranium ions with [...] Read more.

With metallic-magnetic calorimeters (MMCs), promising detectors for high-precision X-ray spectrometry in atomic and fundamental physics experiments are available. In this work, we present a pilot experiment based on a maXs-30 type MMC-spectrometer for recording X-rays emitted in collisions of lithium-like uranium ions with a molecular nitrogen gas jet in the internal target of the ESR storage ring of the GSI. Sample spectra have been measured, and a multitude of X-ray transitions have been unambiguously identified. As a first test and for comparison with data recorded at an EBIT, the 2s Lamb shift in lithium-like uranium was estimated. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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10 pages, 6728 KiB

Open AccessArticle

Collinear Laser Spectroscopy of Helium-like ¹¹B³⁺

by Konstantin Mohr, Axel Buß, Zoran Andelkovic, Volker Hannen, Max Horst, Phillip Imgram, Kristian König, Bernhard Maaß, Wilfried Nörtershäuser, Simon Rausch, Rodolfo Sánchez and Christian Weinheimer

Atoms 2023, 11(1), 11; https://doi.org/10.3390/atoms11010011 - 11 Jan 2023

Cited by 2 | Viewed by 1767

Abstract

Collinear laser spectroscopy in the

1 s 2 s^{3} S_{1} \to 1 s 2 p^{3} P_{0, 2}

transitions of helium-like

^{11}

B

^{3 +}

was performed using the HITRAP beamline at the GSI Helmholtz Centre. The ions were [...] Read more.

Collinear laser spectroscopy in the

1 s 2 s^{3} S_{1} \to 1 s 2 p^{3} P_{0, 2}

transitions of helium-like

^{11}

B

^{3 +}

was performed using the HITRAP beamline at the GSI Helmholtz Centre. The ions were produced in an electron beam ion source, extracted, and accelerated to a beam energy of 4 keV/q. Results agree with previous measurements within uncertainty. Thus, it was demonstrated that the metastable state in He-like ions is sufficiently populated to carry out collinear laser spectroscopy. The measurement is a pilot experiment for a series of measurements that will be performed at a dedicated collinear laser spectroscopy setup at TU Darmstadt with light helium-like ions. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 450 KiB

Open AccessArticle

Preliminary Results for Observation of Radiative Double-Electron Capture by F^9+,8+ on Graphene

by D. S. La Mantia, A. Kayani, K. Bhatt and J. A. Tanis

Atoms 2023, 11(1), 6; https://doi.org/10.3390/atoms11010006 - 31 Dec 2022

Viewed by 1575

Abstract

Radiative double-electron capture, which can be considered the inverse of double photoionization, has been investigated for 2.11 MeV/u F

^{9 +}

and F

^{8 +}

projectiles colliding with the two-dimensional target single-layer graphene. Preliminary results for the cross sections are obtained and presented [...] Read more.

Radiative double-electron capture, which can be considered the inverse of double photoionization, has been investigated for 2.11 MeV/u F

^{9 +}

and F

^{8 +}

projectiles colliding with the two-dimensional target single-layer graphene. Preliminary results for the cross sections are obtained and presented and compared with our previous measurements for the one-dimensional gas targets N

_{2}

and Ne, with the three-dimensional target thin-foil C, and with the most accurate theoretical results that currently exist. The graphene results reported here are reasonable when compared with the F

^{9 +}

+N

_{2}

, Ne results given the thicknesses of the respective targets, being larger by about a factor of four. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 433 KiB

Open AccessArticle

Exploitation of the Timing Capabilities of Metallic Magnetic Calorimeters for a Coincidence Measurement Scheme

by Philip Pfäfflein, Günter Weber, Steffen Allgeier, Sonja Bernitt, Andreas Fleischmann, Marvin Friedrich, Christoph Hahn, Daniel Hengstler, Marc Oliver Herdrich, Anton Kalinin, Felix Martin Kröger, Patricia Kuntz, Michael Lestinsky, Bastian Löher, Esther Babette Menz, Uwe Spillmann, Binghui Zhu, Christian Enss and Thomas Stöhlker

Atoms 2023, 11(1), 5; https://doi.org/10.3390/atoms11010005 - 31 Dec 2022

Cited by 1 | Viewed by 1729

Abstract

In this report, we compare two filter algorithms for extracting timing information using novel metallic magnetic calorimeter detectors, applied to the precision X-ray spectroscopy of highly charged ions in a storage ring. Accurate timing information is crucial when exploiting coincidence conditions for background [...] Read more.

In this report, we compare two filter algorithms for extracting timing information using novel metallic magnetic calorimeter detectors, applied to the precision X-ray spectroscopy of highly charged ions in a storage ring. Accurate timing information is crucial when exploiting coincidence conditions for background suppression to obtain clean spectra. For X-rays emitted by charge-changing interactions between ions and a target, this is a well-established technique when relying on conventional semiconductor detectors that offer a good temporal resolution. However, until recently, such a coincidence scheme had never been realized with metallic magnetic calorimeters, which typically feature much longer signal rise times. In this report, we present optimized timing filter algorithms for this type of detector. Their application to experimental data recently obtained at the electron cooler of CRYRING@ESR at GSI, Darmstadt is discussed. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 1373 KiB

Open AccessArticle

Radiative Recombination Studies for Bare Lead Ions Interacting with Low-Energy Electrons

by Binghui Zhu and Thomas Stöhlker

Atoms 2023, 11(1), 2; https://doi.org/10.3390/atoms11010002 - 21 Dec 2022

Cited by 1 | Viewed by 1518

Abstract

X-ray emission as a result of radiative recombination (RR) at threshold energies in the electron cooler of CRYRING@ESR was investigated for decelerated bare lead ions at a beam energy of 10 MeV/u. The recorded spectra are dominated by characteristic transitions in Pb [...] Read more.

X-ray emission as a result of radiative recombination (RR) at threshold energies in the electron cooler of CRYRING@ESR was investigated for decelerated bare lead ions at a beam energy of 10 MeV/u. The recorded spectra are dominated by characteristic transitions in Pb

^{81 +}

, namely, the Lyman, Balmer and Paschen series, as a result of decay cascades from high-n states that are preferentially populated by the RR processes. In addition, a rigorous theoretical model is applied for the interpretation of measured X-ray spectra, and shows good agreement. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 2305 KiB

Open AccessArticle

Higher-Order Recombination Processes in Argon Ions Observed via X-ray Emission in an EBIT

by Weronika Biela-Nowaczyk, Pedro Amaro, Filipe Grilo and Andrzej Warczak

Atoms 2023, 11(1), 1; https://doi.org/10.3390/atoms11010001 - 21 Dec 2022

Cited by 2 | Viewed by 1773

Abstract

In electron–ion collisions, recombination processes play a very important role. Recently, multielectron recombination processes have been highly investigated, as they carry information about electron–electron interaction. Among them, the most basic process is dielectronic recombination (DR). The research presented here was conducted using an [...] Read more.

In electron–ion collisions, recombination processes play a very important role. Recently, multielectron recombination processes have been highly investigated, as they carry information about electron–electron interaction. Among them, the most basic process is dielectronic recombination (DR). The research presented here was conducted using an EBIT at Jagiellonian University. Using X-ray spectroscopy, we conducted research into K-LL, K-LM, K-LN, K-LO and K-MM resonances. The aim of this study was to investigate the contribution of the intershell higher-order recombination processes in collected spectra. A good resolution for the K-LL DR spectrum made it possible to distinguish structures for He- up to C-like Ar ions. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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6 pages, 2476 KiB

Open AccessArticle

Optical Lines of Ru²¹⁺ to Ru²⁴⁺ Ions

by Junyu Fan, Zihuan Jiang, Yuyuan Qian, Jialin Liu, Pengcheng Xu, Liangyu Huang, Zhencen He, Yaming Zou, Jiguang Li, Chongyang Chen and Ke Yao

Atoms 2022, 10(4), 154; https://doi.org/10.3390/atoms10040154 - 15 Dec 2022

Cited by 4 | Viewed by 1591

Abstract

In this work, we report a spectroscopy measurement of Ru

^{21 +}

to Ru

^{24 +}

ions in the optical region using a low energy electron beam ion trap. Twelve lines were observed. The multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction methods were used [...] Read more.

In this work, we report a spectroscopy measurement of Ru

^{21 +}

to Ru

^{24 +}

ions in the optical region using a low energy electron beam ion trap. Twelve lines were observed. The multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction methods were used to calculate the atomic level energies and the transition rates. With the assistance of the theoretical results, eleven magnetic dipole lines were identified. The experimental results provide new reference data for further theoretical investigations of the complex ions. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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6 pages, 1406 KiB

Open AccessArticle

Toward Probing Surface Magnetism with Highly Charged Ions

by Perla Dergham, Friedrich Aumayr, Emily Lamour, Stéphane Macé, Christophe Prigent, Sébastien Steydli, Dominique Vernhet, Matthias Werl, Richard Arthur Wilhelm and Martino Trassinelli

Atoms 2022, 10(4), 151; https://doi.org/10.3390/atoms10040151 - 13 Dec 2022

Cited by 2 | Viewed by 1641

Abstract

X-rays produced during collisions between Highly Charged Ions (HCI) and sample surfaces can potentially be used to investigate the surface’s magnetic properties, taking advantage of the (partial) conservation of the spin of the electrons captured by the ion during the collision. We conducted [...] Read more.

X-rays produced during collisions between Highly Charged Ions (HCI) and sample surfaces can potentially be used to investigate the surface’s magnetic properties, taking advantage of the (partial) conservation of the spin of the electrons captured by the ion during the collision. We conducted studies to characterize the X-ray detection system and to determine, with a sub-degree accuracy, the incident angle between the incoming ions and the sample surfaces. A series of proof-of-principle experiments are presented involving an Ar¹⁷⁺ ion beam interacting with a nonmagnetic Si sample. The obtained X-ray spectra show a significant dependency in terms of X-ray yield and energy on the ion incidence angle. These findings will be used to guide future ion–magnetic surface studies. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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6 pages, 3127 KiB

Open AccessArticle

Generation of Highly Charged Au Ion in Laser-Produced Plasma for Water Window X-ray Radiation Sources

by Jiahao Wang, Maki Kishimoto, Tomoyuki Johzaki, Kairi Mizushima, Chihiro Kumeda, Takeshi Higashiguchi, Atsushi Sunahara, Hikari Ohiro, Kotaro Yamasaki and Shinichi Namba

Atoms 2022, 10(4), 150; https://doi.org/10.3390/atoms10040150 - 9 Dec 2022

Viewed by 2097

Abstract

Highly charged ions in the plasma produced by high-power laser can radiate bright and short-pulse X-rays. Owing to the unresolved transition array (UTA) from the high-Z elements, laser produced plasma has been applied for developing X-ray sources. In particular, X-rays in the water-window [...] Read more.

Highly charged ions in the plasma produced by high-power laser can radiate bright and short-pulse X-rays. Owing to the unresolved transition array (UTA) from the high-Z elements, laser produced plasma has been applied for developing X-ray sources. In particular, X-rays in the water-window (WW) region (2.3–4.4 nm) is utilized as the light source of the X-ray microscopy to observe living organisms under high contrast and resolution. In this work, WW X-rays radiated from a laser (1064 nm, 6.2 ns) produced Au-plasma has been studied. UTA spectrum in the WW range has been observed through a grazing incident spectrometer (GIS). Dependence of Au-ion charge state distribution on laser intensity has been experimentally investigated and evaluated by a transition probability data calculated by the flexible atomic code. The integrated soft X-ray emission has been observed through a pinhole camera with a 1.0-μm Ti-filter, combined with a 2-D plasma radiation scanning achieved by the GIS. An intense WW emission region 200-μm away from the target surface has been observed, which indicates a more effective area is possible to be utilized for a practical use. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 291 KiB

Open AccessArticle

High-Resolution Laboratory Measurements and Identification of Fe IX Lines near 171 Å

by Peter Beiersdorfer, Jaan K. Lepson, Gregory V. Brown, Natalie Hell, Elmar Träbert, Michael Hahn and Daniel W. Savin

Atoms 2022, 10(4), 148; https://doi.org/10.3390/atoms10040148 - 8 Dec 2022

Cited by 3 | Viewed by 1579

Abstract

A multitude of weaker Fe IX lines have been predicted in the vicinity of the strong 171 Å line that dominates the spectra of many astrophysical and laboratory sources. Some of these weaker lines have only recently been identified in the laboratory, albeit [...] Read more.

A multitude of weaker Fe IX lines have been predicted in the vicinity of the strong 171 Å line that dominates the spectra of many astrophysical and laboratory sources. Some of these weaker lines have only recently been identified in the laboratory, albeit some only tentatively. Here, we present measurements on the Livermore EBIT-I electron beam ion trap that span the region from 170.0 to 173.6 Å, which surrounds the 171 Å line. The measurements stepped through electron beam energy to determine the charge state of iron associated with each observed feature. Moreover, we have minimized the presence of oxygen in the trap, because oxygen lines obscured possible Fe IX lines in past measurements and prevented their identification. Our measurement confirms formerly tentative identifications and adds several new assignments. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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6 pages, 3260 KiB

Open AccessArticle

Performance of a keV/u Ion Spectrometer for the FISIC Platform

by Mariette Jolly, Spyridon Voikopoulos, Emily Lamour, Alain Méry, Angela Bräuning-Demian, Jean-Yves Chesnel, Alexandre Gumberidze, Michael Lestinsky, Stéphane Macé, Christophe Prigent, Jean-Marc Ramillon, Jimmy Rangama, Patrick Rousseau, Daniel Schury, Uwe Spillmann, Sébastien Steydli, Thomas Stöhlker, Martino Trassinelli and Dominique Vernhet

Atoms 2022, 10(4), 146; https://doi.org/10.3390/atoms10040146 - 3 Dec 2022

Viewed by 1460

Abstract

The design and performances of a newly built electrostatic charge state analyzer constructed to act as a spectrometer for keV/u ions are reported. It consists of two

90^{\circ}

curved electrodes enclosed by Matsuda electrodes. This setup was recently tested using Ar [...] Read more.

The design and performances of a newly built electrostatic charge state analyzer constructed to act as a spectrometer for keV/u ions are reported. It consists of two

90^{\circ}

curved electrodes enclosed by Matsuda electrodes. This setup was recently tested using Ar

^{9 +}

and Ar

^{12 +}

ion beams at an energy of 10 keV per charge unit. This spectrometer achieves a good separation of different charge states formed by electron capture processes during collisions between primary ions and the residual gas. Thanks to these first tests, we have identified up to three different background contributions on the detector that need to be reduced or suppressed. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 289 KiB

Open AccessArticle

Finite-Basis-Set Approach to the Two-Center Heteronuclear Dirac Problem

by Artem A. Kotov, Dmitry A. Glazov, Aleksei V. Malyshev, Vladimir M. Shabaev and Günter Plunien

Atoms 2022, 10(4), 145; https://doi.org/10.3390/atoms10040145 - 2 Dec 2022

Cited by 2 | Viewed by 1604

Abstract

The rigorous two-center approach based on the dual-kinetically balanced finite-basis-set expansion is applied to one-electron, heteronuclear diatomic Bi-Au, U-Pb, and Cf-U quasimolecules. The obtained

1 σ

ground-state energies are compared with previous calculations, when possible. Upon analysis of three different placements of the [...] Read more.

The rigorous two-center approach based on the dual-kinetically balanced finite-basis-set expansion is applied to one-electron, heteronuclear diatomic Bi-Au, U-Pb, and Cf-U quasimolecules. The obtained

1 σ

ground-state energies are compared with previous calculations, when possible. Upon analysis of three different placements of the coordinate system’s origin in the monopole approximation of the two-center potential: (1) in the middle, between the nuclei, (2) in the center of the heavy nucleus, and (3) in the center of the light nucleus, a substantial difference between the results is found. The leading contributions of one-electron quantum electrodynamics (self-energy and vacuum polarization) are evaluated within the monopole approximation as well. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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8 pages, 362 KiB

Open AccessArticle

Electron Capture and Ionisation in Collisions of Ne¹⁰⁺ and Li³⁺ with Atomic Hydrogen

by Aks M. Kotian, Corey T. Plowman, Ilkhom B. Abdurakhmanov, Igor Bray and Alisher S. Kadyrov

Atoms 2022, 10(4), 144; https://doi.org/10.3390/atoms10040144 - 1 Dec 2022

Cited by 3 | Viewed by 1687

Abstract

The two-center wave-packet convergent close-coupling method has been applied to model the processes of electron capture and ionisation in collisions of fully stripped neon and lithium ions with atomic hydrogen at projectile energies from 1 keV/u to 1 MeV/u. For the Ne [...] Read more.

The two-center wave-packet convergent close-coupling method has been applied to model the processes of electron capture and ionisation in collisions of fully stripped neon and lithium ions with atomic hydrogen at projectile energies from 1 keV/u to 1 MeV/u. For the Ne

^{10 +}

projectile, the resulting total electron-capture cross section lies between the two sets of experimental results available for system, which differ from each other significantly. For Li

^{3 +}

, our total electron-capture cross section agrees with the available experimental measurements by Shah et al. [J. Phys. B: At. Mol. Opt. Phys 11, L233 (1978)] and Seim et al. [J. Phys. B: At. Mol. Opt. Phys 14, 3475 (1981)], particularly at low and high energies. We also get good agreement with the existing theoretical works, particularly the atomic- and molecular-orbital close-coupling calculations. Our total ionisation cross section overestimates the experimental data by Shah et al. [J. Phys. B: At. Mol. Opt. Phys 15, 413 (1982)] at the peak, however we get good agreement with the other existing theoretical calculations at low and high energies. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 2956 KiB

Open AccessArticle

Commissioning of the HITRAP Cooling Trap with Offline Ions

by Simon Rausch, Max Horst, Zoran Andelkovic, Svetlana Fedotova, Wolfgang Geithner, Frank Herfurth, Dennis Neidherr, Wilfried Nörtershäuser, Nils Stallkamp, Sergiy Trotsenko and Gleb Vorobyev

Atoms 2022, 10(4), 142; https://doi.org/10.3390/atoms10040142 - 22 Nov 2022

Cited by 1 | Viewed by 1378

Abstract

Highly charged heavy ions at rest offer a wide spectrum of precision measurements. The GSI Helmholtzzentrum für Schwerionenforschung GmbH is able to deliver ions up to U

^{92 +}

. As the production of these heavy, highly charged ions requires high kinetic energies, [...] Read more.

Highly charged heavy ions at rest offer a wide spectrum of precision measurements. The GSI Helmholtzzentrum für Schwerionenforschung GmbH is able to deliver ions up to U

^{92 +}

. As the production of these heavy, highly charged ions requires high kinetic energies, it is necessary to decelerate these ions for ultimate precision. The broad energy distribution, which results from the deceleration in the HITRAP linear decelerator, needs to be reduced to allow for further transportation and experiments. The HITRAP cooling trap is designed to cool, i.e., reduce, this energy spread by utilizing electron cooling. The commissioning of this trap is done with Ar

^{16 +}

-ions from a local EBIT ion source. By analyzing the signal of stored ions after ejection, properties such as ion lifetime, charge exchange, and ion motions can be observed. Here, we provide an overview of the recent results of the commissioning process and discuss future experiments. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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10 pages, 1657 KiB

Open AccessArticle

First Experiments with CRYRING@ESR

by Michael Lestinsky, Esther Babette Menz, Håkan Danared, Claude Krantz, Eva Lindroth, Zoran Andelkovic, Carsten Brandau, Angela Bräuning-Demian, Svetlana Fedotova, Wolfgang Geithner, Frank Herfurth, Anton Kalinin, Ingrid Kraus, Uwe Spillmann, Gleb Vorobyev and Thomas Stöhlker

Atoms 2022, 10(4), 141; https://doi.org/10.3390/atoms10040141 - 16 Nov 2022

Cited by 2 | Viewed by 1944

Abstract

The low-energy heavy ion storage ring CRYRING was transported from Stockholm to Darmstadt, modernized and reconfigured, and recommissioned as CRYRING@ESR. The machine is now in operation with all installations in service and is available as a user facility for experiments proposed through the [...] Read more.

The low-energy heavy ion storage ring CRYRING was transported from Stockholm to Darmstadt, modernized and reconfigured, and recommissioned as CRYRING@ESR. The machine is now in operation with all installations in service and is available as a user facility for experiments proposed through the SPARC collaboration. During the 2020–2022 period, we brought a number of experimental installations into service and used them to measure first data: the ultra-cold electron cooler for merged-beam electron–ion collisions, the gas jet target for atomic collisions, a next-generation microcalorimeter-based X-ray spectroscopy setup, and others. Ions can be injected either in low charge states from a local ion source through a 300 keV/u RFQ linac, or in high charge states from the GSI accelerator chain through ESR. This allows for very broad access to ions across the entire periodic table. CRYRING@ESR is able to de- or accelerate ions and cool and store beams of isotopically pure species in a desired charge state. While the analysis is still largely ongoing, the first experimental data already show that the machine reached its expected performance level, and our high expectations regarding achievable resolution in spectroscopy experiments have been fulfilled. With access to new classes of ions available through ESR injection and a new generation of experimental instrumentation, CRYRING@ESR is a unique facility for experiments with heavy, highly charged ions. Here, we will review our present setup and machine performance, discuss the data from our first commissioning experiments and briefly preview the upcoming new installations for the coming years. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 379 KiB

Open AccessArticle

Circular Polarimetry of Hard X-rays with Rayleigh Scattering

by Sophia Strnat, Jonas Sommerfeldt, Vladimir Yerokhin, Wilko Middents, Thomas Stöhlker and Andrey Surzhykov

Atoms 2022, 10(4), 140; https://doi.org/10.3390/atoms10040140 - 16 Nov 2022

Cited by 1 | Viewed by 2159

Abstract

We present a theoretical investigation of the elastic Rayleigh scattering of X-rays by atomic targets. Special attention is paid to the question of how the polarization of the scattered photons is affected if the incident light is itself polarized. In particular, we found [...] Read more.

We present a theoretical investigation of the elastic Rayleigh scattering of X-rays by atomic targets. Special attention is paid to the question of how the polarization of the scattered photons is affected if the incident light is itself polarized. In particular, we found that the circular polarization of the incoming X-rays may lead to a remarkable modification of the linear polarization of the scattered photons. Based on this ’circular-to-linear-polarization-transfer’ and on the fact that the linear polarization of X-rays can be conveniently observed by solid-state Compton detectors, we argue that Rayleigh scattering may be used as a tool for circular polarimetry of hard X-rays. To illustrate our proposal, we performed detailed calculations of 145 and 500 keV circularly polarized photons scattered by lead atoms. Based on these calculations, we found that the photon scattering under large angles with respect to the incident beam direction is most favorable for the circular polarimetry of hard X-rays. In particular, for 500 keV photon energy and scattering angles around 70 deg we found a remarkable modification of the linear polarization of scattered light for the case when the incident radiation is circularly polarized. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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8 pages, 295 KiB

Open AccessArticle

Radiative Properties of Rb-Isoelectronic Technetium (Tc VII), Ruthenium (Ru VIII) and Rhodium (Rh IX) Ions for Astrophysical Applications

by Jyoti, Mandeep Kaur and Bindiya Arora

Atoms 2022, 10(4), 138; https://doi.org/10.3390/atoms10040138 - 11 Nov 2022

Viewed by 1513

Abstract

In this work, we present high-accuracy spectroscopic properties, such as line strengths, transition probabilities and oscillator strengths for allowed transitions among

n D_{3 / 2, 5 / 2}, n^{'} S_{1 / 2}

and [...] Read more.

In this work, we present high-accuracy spectroscopic properties, such as line strengths, transition probabilities and oscillator strengths for allowed transitions among

n D_{3 / 2, 5 / 2}, n^{'} S_{1 / 2}

and

n^{'} P_{1 / 2, 3 / 2} (n = 4, n^{'} = 5, 6)

states of Rb-isoelectronic Tc (Tc VII), Ru (Ru VIII) and Rh (Rh IX) ions for their applications in the analysis of astrophysical phenomena occurring inside celestial bodies containing Tc, Ru and Rh ions. Due to the scarcity of computational data of atomic properties of these transitions, as well as considerable discrepancies within the literature about these ions, the precise determination of these properties is necessary. For this purpose, we have implemented relativistic many-body perturbation theory (RMBPT) for evaluation of the wave functions of the considered states. For better accuracy, we have accounted for electron interactions through random phase approximation, Brückner orbitals and structural radiations of wave functions in our RMBPT method for further precise evaluation of electric dipole amplitudes. Combining these values of the observed wavelengths, the above transition properties and radiative lifetimes, a number of excited states of Tc VII, Ru VIII and Rh IX ions have been calculated. For further validation of our work, we have compared our results with the data already available in the literature. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

7 pages, 283 KiB

Open AccessArticle

Fully-Stripped Beryllium-Ion Collisions with 2ℓm States of Atomic Hydrogen: Target Excitation and Ionisation cross Sections

by Nicholas W. Antonio, Corey T. Plowman, Ilkhom B. Abdurakhmanov, Igor Bray and Alisher S. Kadyrov

Atoms 2022, 10(4), 137; https://doi.org/10.3390/atoms10040137 - 10 Nov 2022

Cited by 5 | Viewed by 1506

Abstract

The wave-packet convergent close-coupling approach is used to calculate integrated target excitation and ionisation cross sections in bare beryllium-ion collisions with the

2 ℓ m

states of atomic hydrogen (where n, ℓ and m are the principal, orbital angular momentum and magnetic [...] Read more.

The wave-packet convergent close-coupling approach is used to calculate integrated target excitation and ionisation cross sections in bare beryllium-ion collisions with the

2 ℓ m

states of atomic hydrogen (where n, ℓ and m are the principal, orbital angular momentum and magnetic quantum numbers, respectively). The calculations are performed at representative projectile energies between 10 keV/u to 1 MeV/u. The calculated cross sections for collisions with H(

2 s

) are compared with recent theoretical results. Generally, good agreement is observed for the n-partial excitation and total ionisation cross sections. However, a significant discrepancy is found for excitation into the dominant

n = 3

states at 100 keV/u, where the target excitation cross-section peaks. We also present the first calculations of the excitation and ionisation cross sections for Be

^{4 +}

collisions with H(

2 p_{0}

) and H(

2 p_{\pm 1}

). Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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6 pages, 2092 KiB

Open AccessArticle

Enhancement of Gain Coefficient of Li-Like Ion 3d-4f Soft X-ray Laser Oscillation by a Single Resonator

by Shinichi Namba, Jiahao Wang, Hikari Ohiro, Jiawei Zhang, Maki Kishimoto, Kotaro Yamasaki, Noboru Hasegawa, Thanhhung Dinh, Masahiko Ishino, Takeshi Higashiguchi and Masaharu Nishikino

Atoms 2022, 10(4), 128; https://doi.org/10.3390/atoms10040128 - 1 Nov 2022

Cited by 1 | Viewed by 1597

Abstract

A recombination plasma soft X-ray laser that is associated with Li-like Aluminum ion Al¹⁰⁺ 3d-4f transition (wavelength: 15.47 nm) was investigated to increase the gain coefficient. By optimizing the time interval of the 16-pulse train, higher-density plasma with a [...] Read more.

A recombination plasma soft X-ray laser that is associated with Li-like Aluminum ion Al¹⁰⁺ 3d-4f transition (wavelength: 15.47 nm) was investigated to increase the gain coefficient. By optimizing the time interval of the 16-pulse train, higher-density plasma with a low temperature could be generated, and thus, we obtained the gain coefficient of 9.84 cm⁻¹ at the pump laser pulse energy which was as low as 3 J. To further enhance the X-ray laser output energy, the single resonator which was installed by using a Mo/Si multilayer mirror that has a high reflectivity of 0.45 at 15.5 nm, and the X-ray spectrum after the double pass in the lasing medium was measured. As a result, the output intensity was increased to be 1.5 times higher than t=when it was compared with those that were conducted with no X-ray mirror. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 1321 KiB

Open AccessArticle

K X-ray Emission for Slow Oxygen Ions Approaching a Copper Metal Surface

by Zhangyong Song, Xuan Liu, Mingwu Zhang, Junkui Xu, Yong Feng, Bingzhang Zhang, Wei Wang, Junliang Liu, Caojie Shao, Deyang Yu, Yanling Guo and Lin Chen

Atoms 2022, 10(4), 124; https://doi.org/10.3390/atoms10040124 - 26 Oct 2022

Viewed by 1489

Abstract

We report on the K X-ray emission for 9–140 keV oxygen ions with initial charge states from 3 to 7 approaching a copper surface. The peak center of the measured X-ray spectrum slightly shifts towards higher energies with the increasing of the initial [...] Read more.

We report on the K X-ray emission for 9–140 keV oxygen ions with initial charge states from 3 to 7 approaching a copper surface. The peak center of the measured X-ray spectrum slightly shifts towards higher energies with the increasing of the initial charge state of the incident ions. For the collisions of oxygen ions with no K-vacancies (q = 3–6), the X-ray yield per incident ion increases gradually with the projectile’s kinetic energy, while for the O⁷⁺ ions (with a K-vacancy) it is nearly independent of the energy. The K-shell ionization cross-sections for the oxygen ions with no K-vacancies obtained from the experiments are well consistent with the calculations of the binary encounter approximation model when the collision energy is larger than 30 keV, whereas they are several times larger than the theoretical values at collision energies of less than 30 keV. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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6 pages, 286 KiB

Open AccessArticle

Atomic Structure of Nd⁹⁺ for Highly Charged Ion Clocks

by Yanmei Yu, Duo Pan, Shaolong Chen, Bindiya Arora, Hua Guan, Kelin Gao and Jingbiao Chen

Atoms 2022, 10(4), 123; https://doi.org/10.3390/atoms10040123 - 25 Oct 2022

Cited by 6 | Viewed by 1548

Abstract

The energy levels arising from the electronic orbital

5 p - 4 f

crossing between the ground

5 p^{2} 4 f

and excited

5 p 4 f^{2}

configurations in the Nd

^{9 +}

ion are investigated by using high-accuracy relativistic ab [...] Read more.

The energy levels arising from the electronic orbital

5 p - 4 f

crossing between the ground

5 p^{2} 4 f

and excited

5 p 4 f^{2}

configurations in the Nd

^{9 +}

ion are investigated by using high-accuracy relativistic ab initio calculations. The accurate atomic data of the lifetime,

g_{J}

factor, electric quadrupole moment, and hyperfine structure of the magnetic dipole are also presented. The long-lived states that are suitable for making narrow-linewidth (milli-Hz) clock lines are found. Dominant systematics caused by stray electromagnetic interactions in an experiment and the coefficients of the relativistic sensitivityto variation of the fine-structure constant

α

and of the Lorentz invariance violation are evaluated, thus validating that the Nd

^{9 +}

ion can be a new candidate for high-resolution spectroscopy and precision fundamental studies for probing new physics beyond the Standard Model. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

8 pages, 5061 KiB

Open AccessArticle

Recent Developments in MaMFIS Technology for the Production of Highly Charged Ions

by Vladimir P. Ovsyannikov, Andrei V. Nefiodov, Alexander Yu. Ramzdorf and Aleksandr A. Levin

Atoms 2022, 10(4), 120; https://doi.org/10.3390/atoms10040120 - 24 Oct 2022

Viewed by 1769

Abstract

We present results for the production of highly charged ions in a rippled electron beam propagating in a multi-section drift tube with different electrostatic potentials in an axial magnetic focusing field. The inner-shell ionization of target atoms by electron impact occurs in local [...] Read more.

We present results for the production of highly charged ions in a rippled electron beam propagating in a multi-section drift tube with different electrostatic potentials in an axial magnetic focusing field. The inner-shell ionization of target atoms by electron impact occurs in local ion traps formed at the electron-beam crossovers. The utmost electron current density achieved is assessed at ~10 kA/cm

^{2}

. The successive ionization of cathode materials and working substances such as xenon and bismuth was investigated as a function of the confinement time. The characteristic X-ray radiation from ions including Ir

^{62 +}

, Ce

^{48 +}

, Xe

^{46 +}

, and Bi

^{60 +}

was detected. It is shown that it is possible to extract highly charged ions from local ion traps for a certain geometry of the drift tube structure and a certain distribution of the electric potentials. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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7 pages, 404 KiB

Open AccessEditor’s ChoiceArticle

Laboratory Search for Fe IX Solar Diagnostic Lines Using an Electron Beam Ion Trap

by Elmar Träbert, Peter Beiersdorfer, Gregory V. Brown, Natalie Hell, Jaan K. Lepson, Alexander J. Fairchild, Michael Hahn and Daniel W. Savin

Atoms 2022, 10(4), 115; https://doi.org/10.3390/atoms10040115 - 16 Oct 2022

Cited by 7 | Viewed by 1704

Abstract

The Fe IX spectrum features two lines in the extreme ultraviolet whose ratio has been rated among the best density diagnostics in the solar spectrum. One line is an

E 1

-allowed intercombination transition at 244.909 Å, the other an

E 1

-forbidden [...] Read more.

The Fe IX spectrum features two lines in the extreme ultraviolet whose ratio has been rated among the best density diagnostics in the solar spectrum. One line is an

E 1

-allowed intercombination transition at 244.909 Å, the other an

E 1

-forbidden

M 2

transition at 241.739 Å. Employing a medium and a high resolution spectrometer at the Livermore EBIT-I electron beam ion trap, we have observed the line pair in the laboratory for the first time. Using a CHIANTI model computation, the observed line ratio yields a value of the electron density that is compatible with typical densities in our device. Full article

(This article belongs to the Special Issue 20th International Conference on the Physics of Highly Charged Ions)

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