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Informing spectral models for dense plasmas with K-edge absorption measurements of warm dense copper
Authors:
T. Cordova,
E. V. Marley,
D. A. Chin,
R. A. London,
S. B. Hansen,
S. M. Vinko,
J. E. Pask,
H. A. Scott,
H. P. Le,
D. Aberg,
M. K. G. Kruse,
T. Döppner,
F. N. Beg,
J. Emig,
P. M. Nilson,
P. Sterne,
M. J. MacDonald
Abstract:
Warm dense matter remains a challenging regime to characterize experimentally and to model with predictive accuracy. Recent experimental platforms have been developed to generate, characterize, and diagnose uniform warm dense matter, enabling detailed comparisons with models. Here, we present experiments conducted at the OMEGA laser facility that compress and heat a buried layer target to warm den…
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Warm dense matter remains a challenging regime to characterize experimentally and to model with predictive accuracy. Recent experimental platforms have been developed to generate, characterize, and diagnose uniform warm dense matter, enabling detailed comparisons with models. Here, we present experiments conducted at the OMEGA laser facility that compress and heat a buried layer target to warm dense matter conditions, where the targets are heated to temperatures of approximately 20 eV and compressed to densities of 25 g/cm^3. We probe the warm dense plasma using x-ray absorption spectroscopy, using the K-edge and bound-bound absorption features to constrain the temperature and charge state distribution of the plasma. We compare these measurements with two types of models: collisional-radiative models with detailed electronic structure and ad-hoc density effects, and a multi-ion model based on density functional theory in combination with excited-state projector augmented-wave potentials. Neither approach fully reproduces the observed data, We show that the broad structure and position of the K-edge region can be modeled using density functional theory in combination with excited-state projector augmented-wave potentials. The density functional theory results are contrasted with a collisional-radiative model approach that incorporates ad-hoc density effects, which show incomplete agreement with the experimental observations, highlighting a need for improved density-dependent atomic modeling in warm dense plasmas.
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Submitted 19 August, 2026;
originally announced August 2026.
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Physics-Informed Latent Space Dynamics Identification for Time-Dependent NLTE Atomic Kinetics
Authors:
Jeongwoo Nam,
William Anderson,
Youngsoo Choi,
Hai P. Le,
Mark E. Foord,
Byoung Ick Cho,
Haewon Jeong,
Min Sang Cho
Abstract:
Non-local thermodynamic equilibrium (NLTE) calculations remain a major computational bottleneck in radiation--hydrodynamics, while most existing machine-learning surrogates treat NLTE as a static input--output mapping rather than a kinetic evolution problem. Here, we present a physics-informed Latent Space Dynamics Identification (pLaSDI) framework specifically designed for NLTE atomic kinetics, w…
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Non-local thermodynamic equilibrium (NLTE) calculations remain a major computational bottleneck in radiation--hydrodynamics, while most existing machine-learning surrogates treat NLTE as a static input--output mapping rather than a kinetic evolution problem. Here, we present a physics-informed Latent Space Dynamics Identification (pLaSDI) framework specifically designed for NLTE atomic kinetics, which captures the time-dependent atomic kinetics of non-equilibrium plasmas through an explicit reduced governing equation. To ensure the physical reliability of the reduced model, we impose physics-informed loss terms that enforce macroscopic consistency, dynamical stability, and convergence to the correct steady state during long-time integration. Applied to tin NLTE population data generated along hydrodynamically modeled temperature--density trajectories relevant to extreme ultraviolet (EUV) lithography plasmas, the model accurately reproduces charge-state evolution and mean charge state with errors below 2\%, achieves speedups of approximately $5\times10^{4}$--$10^{5}$, and remains stable outside the training trajectories by converging toward physically admissible states and the correct steady-state solution under fixed plasma conditions. These results show that careful physics-informed design of the latent dynamics, rather than data fitting alone, is essential for constructing fast, stable, and physically reliable extrapolative surrogates for time-dependent NLTE kinetics.
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Submitted 17 April, 2026;
originally announced April 2026.
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Mastering Preclinical Fast MRSI: From Setup to Execution
Authors:
Gianna Nossa,
Eloïse Mougel,
Brayan Alves,
Tan Toi Phan,
Alessio Siviglia,
Thi Ngoc Anh Dinh,
Thanh Phong Lê,
Bernard Lanz,
Cristina Cudalbu
Abstract:
MR experiments are essential for studying brain metabolism, yet preclinical 1H-MRSI remains underdeveloped, with significant limitations in SNR, acquisition speed, and automated data processing. Although recent advances-such as accelerated sequences, denoising strategies, and ultra-high-field systems-have begun to reduce these barriers, preclinical MRSI still lags far behind the human research fie…
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MR experiments are essential for studying brain metabolism, yet preclinical 1H-MRSI remains underdeveloped, with significant limitations in SNR, acquisition speed, and automated data processing. Although recent advances-such as accelerated sequences, denoising strategies, and ultra-high-field systems-have begun to reduce these barriers, preclinical MRSI still lags far behind the human research field in accessibility and routine use. Based on our expertise, we have created this guide that outlines a complete workflow for acquiring and analyzing high-quality fast MRSI data in rodent brains at ultra-high fields (9.4T and 14.1T), enabling novice users to perform reliable experiments using optimized MRSI sequences (FID-MRSI, SE-MRSI, and PRESS-MRSI) and standardized processing pipelines, while also highlighting strategies to further improve acquisition speed, coverage, and reproducibility. Overall, this paper provides a strong foundation for future methodological advances that will expand metabolic imaging capabilities and deepen insights into brain function and disease.
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Submitted 12 December, 2025;
originally announced December 2025.
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Optimization and application of ultra-high field preclinical high-resolution and 3D 1H-MRSI using compressed sensing
Authors:
Brayan Alves,
Thanh Phong Lê,
Gianna Nossa,
Tan Toi Phan,
Alessio Siviglia,
Bernard Lanz,
Wolfgang Bogner,
Antoine Klauser,
Bernhard Strasser,
Cristina Cudalbu
Abstract:
Proton magnetic resonance spectroscopic imaging (1H-MRSI) at ultra-high field has seen an increase in usage in the preclinical field. Challenges related to long acquisition time and low concentration of brain metabolites in the rodent brain have led to the development and application of acceleration schemes for 3D-1H-MRSI, such the undersampling technique Compressed Sensing (CS). This present stud…
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Proton magnetic resonance spectroscopic imaging (1H-MRSI) at ultra-high field has seen an increase in usage in the preclinical field. Challenges related to long acquisition time and low concentration of brain metabolites in the rodent brain have led to the development and application of acceleration schemes for 3D-1H-MRSI, such the undersampling technique Compressed Sensing (CS). This present study aims to explore the CS tool in the context of preclinical in vivo application in order to achieve high-resolution MRSI acquisition in both 2D with an in-plane increase and 3D/multi-slice acquisition with through-plane. The parameters are explored to achieve the highest acceleration possible as a way to make 3D as time efficient as possible. Results of the parameter study showed that an acceleration factor (AF) of 4 was possible with the right sampling size of the core at the center of the k-space. With this specific set, higher matrix size resulting in sub 1 μL nominal voxel size was explored with 2D-FID-MRSI and 9 supplementary phase-encoding/slices were added to achieve 3D-FID-MRSI. The spectral quality and the metabolic maps were accurate enough in the comparison with the non-accelerated 2D-FID-MRSI, within the slice of interest. Issues related with the point spread function (PSF) were noted throughout the different usage of CS. Our work presents a robust and effective protocol to achieve 3D-1H-MRSI using CS in order to reach an acquisition time below the 30 minutes bar, with minimal technical limitations and high-quality acquisition.
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Submitted 28 November, 2025;
originally announced November 2025.
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Impact of super-Gaussian electron distributions on plasma K-shell emission
Authors:
H. P. Le,
E. V. Marley,
H. A. Scott
Abstract:
Electron distributions in laser-produced plasmas will be driven toward a super-Gaussian distribution due to inverse bremsstrahlung absorption [Langdon, Phys. Rev. Lett. 44, 575 (1980)]. Both theoretical and experimental evidence suggest that fundamental plasma properties are altered by the super-Gaussian distribution. This paper examines how the super-Gaussian distribution affects the ionization b…
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Electron distributions in laser-produced plasmas will be driven toward a super-Gaussian distribution due to inverse bremsstrahlung absorption [Langdon, Phys. Rev. Lett. 44, 575 (1980)]. Both theoretical and experimental evidence suggest that fundamental plasma properties are altered by the super-Gaussian distribution. This paper examines how the super-Gaussian distribution affects the ionization balance and K-shell emission of atomic plasmas, utilizing approximate formulas and detailed collisional-radiative simulations. While the impact on plasma ionization is small, K-shell spectra can be significantly modified. Based on these findings, we demonstrate that K-shell spectroscopy can be used to infer super-Gaussian or other similar non-equilibrium electron distributions.
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Submitted 3 July, 2025;
originally announced July 2025.
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Field-effect detected magnetic resonance of NV centers in diamond based on all-carbon Schottky contacts
Authors:
Xuan Phuc Le,
Ludovic Mayer,
Simone Magaletti,
Martin Schmidt,
Jean-François Roch,
Thierry Debuisschert
Abstract:
The nitrogen vacancy (NV) center is a defect in diamond whose spin state can be read optically by exploiting its photoluminescence or electrically by exploiting its charge generation rate under illumination, both of which being spin-dependent. The latter method offers numerous opportunities in terms of integration and performance compared to conventional optical reading. Here, we investigate the p…
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The nitrogen vacancy (NV) center is a defect in diamond whose spin state can be read optically by exploiting its photoluminescence or electrically by exploiting its charge generation rate under illumination, both of which being spin-dependent. The latter method offers numerous opportunities in terms of integration and performance compared to conventional optical reading. Here, we investigate the physical properties of a graphitic-diamond-graphitic structure under illumination. We show how, for a type IIa diamond material, electron-hole pairs generated by an ensemble of NV centers lead to a p-type material upon illumination, making this all-carbon structure equivalent to two back-to-back Schottky diodes. We analyze how the reverse current flowing upon illumination changes as a function of bias voltage and radiofrequency-induced excitation of the NV ensemble spin resonances. Furthermore, we demonstrate how an additional field effect arising from the illumination scheme affects the reverse current, resulting in a photoelectrical signal that can exceed the optical signal under the same illumination conditions.
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Submitted 15 April, 2025;
originally announced April 2025.
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Physics-Informed Transformation Toward Improving the Machine-Learned NLTE Models of ICF Simulations
Authors:
Min Sang Cho,
Paul E. Grabowski,
Kowshik Thopalli,
Thathachar S. Jayram,
Michael J. Barrow,
Jayaraman J. Thiagarajan,
Rushil Anirudh,
Hai P. Le,
Howard A. Scott,
Joshua B. Kallman,
Branson C. Stephens,
Mark E. Foord,
Jim A. Gaffney,
Peer-Timo Bremer
Abstract:
The integration of machine learning techniques into Inertial Confinement Fusion (ICF) simulations has emerged as a powerful approach for enhancing computational efficiency. By replacing the costly Non-Local Thermodynamic Equilibrium (NLTE) model with machine learning models, significant reductions in calculation time have been achieved. However, determining how to optimize machine learning-based N…
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The integration of machine learning techniques into Inertial Confinement Fusion (ICF) simulations has emerged as a powerful approach for enhancing computational efficiency. By replacing the costly Non-Local Thermodynamic Equilibrium (NLTE) model with machine learning models, significant reductions in calculation time have been achieved. However, determining how to optimize machine learning-based NLTE models in order to match ICF simulation dynamics remains challenging, underscoring the need for physically relevant error metrics and strategies to enhance model accuracy with respect to these metrics. Thus, we propose novel physics-informed transformations designed to emphasize energy transport, use these transformations to establish new error metrics, and demonstrate that they yield smaller errors within reduced principal component spaces compared to conventional transformations.
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Submitted 13 November, 2024;
originally announced November 2024.
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Extended electrochemical monitoring of biomolecular binding using commercially available, reusable electrodes in microliter volumes
Authors:
Jeremy Mendez,
Yae Eun Kim,
Nafisah Chowdhury,
Alexios Tziranis,
Phuong Le,
Angela Tran,
Rocio Moron,
Julia Rogers,
Aohona Chowdhury,
Elijah Wall,
Netzahualcóyotl Arroyo-Currás,
Philip Lukeman
Abstract:
Electrochemical biosensors ("E-AB" or "E-DNA" type sensors) that utilize square-wave voltammetry originated in academic labs with a few standard experimental configurations for the electrochemical cell and data analysis. We report here on adaptations of these approaches that are friendly to novice scientists such as those in undergraduate laboratories. These approaches utilize commercially availab…
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Electrochemical biosensors ("E-AB" or "E-DNA" type sensors) that utilize square-wave voltammetry originated in academic labs with a few standard experimental configurations for the electrochemical cell and data analysis. We report here on adaptations of these approaches that are friendly to novice scientists such as those in undergraduate laboratories. These approaches utilize commercially available components, low volumes, work over extended periods and enable facile analysis using a custom excel sheet.
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Submitted 31 October, 2024;
originally announced October 2024.
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Ionization Dynamics in Intense Laser-Produced Plasmas
Authors:
M. S. Cho,
A. L. Milder,
W. Rozmus,
H. P. Le,
H. A. Scott,
D. T. Bishel,
D. Turnbull,
S. B. Libby,
M. E. Foord
Abstract:
The ionization dynamic of argon plasma irradiated by an intense laser is investigated to understand transient physics in dynamic systems. This study demonstrates that significant delayed ionization responses and stepwise ionization processes are crucial factors in determining the ionization state of such systems. When an intense laser begins to ionize an initially cold argon plasma, the conditions…
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The ionization dynamic of argon plasma irradiated by an intense laser is investigated to understand transient physics in dynamic systems. This study demonstrates that significant delayed ionization responses and stepwise ionization processes are crucial factors in determining the ionization state of such systems. When an intense laser begins to ionize an initially cold argon plasma, the conditions change rapidly, leading to a delayed response in ionization. Consequently, the dynamics do not reach a steady state, even if the electron temperature and density appear unchanged, particularly when the atomic transition process is not sufficiently rapid compared to the relevant time scales. Furthermore, in this case, numerous highly excited states are created primarily through collisional excitation. Thus, even low-energy photons can predominantly ionize plasmas, challenging the conventional belief that such photon energies insufficient to overcome the binding energy of bound electrons typically contribute less to the ionization. These findings underscore the necessity of incorporating these processes in ionization modeling within radiation hydrodynamic simulations for various laser-plasma experiments.
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Submitted 20 January, 2026; v1 submitted 18 July, 2024;
originally announced July 2024.
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Plasma screening in mid-charged ions observed by K-shell line emission
Authors:
M. Šmıd,
O. Humphries,
C. Baehtz,
V. Bouffetier,
E. Brambrink,
T. Burian,
V. Cerantola,
M. S. Cho,
T. E. Cowan,
L. Gaus,
M. F. Gu,
V. Hájková,
L. Juha,
J. Kaa,
Z. Konopkova,
H. P. Le,
M. Makita,
X. Pan,
T. Preston,
A. Schropp,
J. P. Schwinkendorf,
H. A. Scott,
R. Štefanıková,
J. Vorberger,
W. Wang
, et al. (2 additional authors not shown)
Abstract:
Dense plasma environment affects the electronic structure of ions via variations of the microscopic electrical fields, also known as plasma screening. This effect can be either estimated by simplified analytical models, or by computationally expensive and to date unverified numerical calculations. We have experimentally quantified plasma screening from the energy shifts of the bound-bound transiti…
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Dense plasma environment affects the electronic structure of ions via variations of the microscopic electrical fields, also known as plasma screening. This effect can be either estimated by simplified analytical models, or by computationally expensive and to date unverified numerical calculations. We have experimentally quantified plasma screening from the energy shifts of the bound-bound transitions in matter driven by the x-ray free electron laser (XFEL). This was enabled by identification of detailed electronic configurations of the observed Kα, K\b{eta} and Kγ lines. This work paves the way for improving plasma screening models including connected effects like ionization potential depression and continuum lowering, which will advance the understanding of atomic physics in Warm Dense Matter regime.
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Submitted 14 October, 2025; v1 submitted 10 June, 2024;
originally announced June 2024.
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Noise-reduction techniques for 1H-FID-MRSI at 14.1T: Monte-Carlo validation & in vivo application
Authors:
Brayan Alves,
Dunja Simicic,
Jessie Mosso,
Thanh Phong Lê,
Guillaume Briand,
Wolfgang Bogner,
Bernard Lanz,
Bernhard Strasser,
Antoine Klauser,
Cristina Cudalbu
Abstract:
Proton magnetic resonance spectroscopic imaging (1H-MRSI) is a powerful tool that enables the multidimensional non-invasive mapping of the neurochemical profile at high-resolution over the entire brain. The constant demand for higher spatial resolution in 1H-MRSI led to increased interest in post-processing-based denoising methods aimed at reducing noise variance. The aim of the present study was…
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Proton magnetic resonance spectroscopic imaging (1H-MRSI) is a powerful tool that enables the multidimensional non-invasive mapping of the neurochemical profile at high-resolution over the entire brain. The constant demand for higher spatial resolution in 1H-MRSI led to increased interest in post-processing-based denoising methods aimed at reducing noise variance. The aim of the present study was to implement two noise-reduction techniques, the Marchenko-Pastur principal component analysis (MP-PCA) based denoising and the low-rank total generalized variation (LR-TGV) reconstruction, and to test their potential and impact on preclinical 14.1T fast in vivo 1H-FID-MRSI datasets. Since there is no known ground truth for in vivo metabolite maps, additional evaluations of the performance of both noise-reduction strategies were conducted using Monte-Carlo simulations. Results showed that both denoising techniques increased the apparent signal-to-noise ratio SNR while preserving noise properties in each spectrum for both in vivo and Monte-Carlo datasets. Relative metabolite concentrations were not significantly altered by either methods and brain regional differences were preserved in both synthetic and in vivo datasets. Increased precision of metabolite estimates was observed for the two methods, with inconsistencies noted on lower concentrated metabolites. Our study provided a framework on how to evaluate the performance of MP-PCA and LR-TGV methods for preclinical 1H-FID MRSI data at 14.1T. While gains in apparent SNR and precision were observed, concentration estimations ought to be treated with care especially for low-concentrated metabolites.
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Submitted 28 March, 2024; v1 submitted 20 September, 2023;
originally announced September 2023.
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Fast high-resolution metabolite mapping in the rat brain using 1H-FID-MRSI at 14.1T
Authors:
Dunja Simicic,
Brayan Alves,
Jessie Mosso,
Guillaume Briand,
Thanh Phong Lê,
Ruud B. van Heeswijk,
Jana Starčuková,
Bernard Lanz,
Antoine Klauser,
Bernhard Strasser,
Wolfgang Bogner,
Cristina Cudalbu
Abstract:
Magnetic resonance spectroscopic imaging (MRSI) enables the simultaneous non-invasive acquisition of MR spectra from multiple spatial locations inside the brain. While 1H-MRSI is increasingly used in the human brain, it is not yet widely applied in the preclinical settings, mostly because of difficulties specifically related to very small nominal voxel size in the rodent brain and low concentratio…
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Magnetic resonance spectroscopic imaging (MRSI) enables the simultaneous non-invasive acquisition of MR spectra from multiple spatial locations inside the brain. While 1H-MRSI is increasingly used in the human brain, it is not yet widely applied in the preclinical settings, mostly because of difficulties specifically related to very small nominal voxel size in the rodent brain and low concentration of brain metabolites, resulting in low signal-to-noise ratio SNR.
In this context, we implemented a free induction decay 1H-MRSI sequence (1H-FID-MRSI) in the rat brain at 14.1T. We combined the advantages of 1H-FID-MRSI with the ultra-high magnetic field to achieve higher SNR, coverage and spatial resolution in the rodent brain, and developed a custom dedicated processing pipeline with a graphical user interface: MRS4Brain toolbox.
LCModel fit, using the simulated metabolite basis-set and in-vivo measured MM, provided reliable fits for the data at acquisition delays of 1.3 and 0.94 ms. The resulting Cramér-Rao lower bounds were sufficiently low (<30%) for eight metabolites of interest, leading to highly reproducible metabolic maps. Similar spectral quality and metabolic maps were obtained between 1 and 2 averages, with slightly better contrast and brain coverage due to increased SNR in the latter case. Furthermore, the obtained metabolic maps were accurate enough to confirm the previously known brain regional distribution of some metabolites. The acquisitions proved high reproducibility over time.
We demonstrated that the increased SNR and spectral resolution at 14.1T can be translated into high spatial resolution in 1H-FID-MRSI of the rat brain in 13 minutes, using the sequence and processing pipeline described herein. High-resolution 1H-FID-MRSI at 14.1T provided reproducible and high-quality metabolic mapping of brain metabolites with significantly reduced technical limitations.
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Submitted 11 December, 2024; v1 submitted 6 July, 2023;
originally announced July 2023.
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Magnetic sensitivity enhancement via polarimetric excitation and detection of an ensemble of NV centers
Authors:
Simone Magaletti,
Ludovic Mayer,
Xuan Phuc Le,
Thierry Debuisschert
Abstract:
The negatively charged nitrogen-vacancy center (NV) presents remarkable spin-dependent optical properties that make it an interesting tool for magnetic field sensing. In this paper we exploit the polarization properties of the NV center absorption and emission processes to improve the magnetic sensitivity of an ensemble of NV centers. By simply equipping the experimental set-up of a half-wave plat…
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The negatively charged nitrogen-vacancy center (NV) presents remarkable spin-dependent optical properties that make it an interesting tool for magnetic field sensing. In this paper we exploit the polarization properties of the NV center absorption and emission processes to improve the magnetic sensitivity of an ensemble of NV centers. By simply equipping the experimental set-up of a half-wave plate in the excitation path and a polarizer in the detection path we demonstrate an improvement larger than a factor of two on the NV center magnetic sensitivity.
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Submitted 30 January, 2023;
originally announced January 2023.
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Mg-doping and free-hole properties of hot-wall MOCVD GaN
Authors:
Alexis Papamichail,
Anelia Kakanakova,
Einar O. Sveinbjörnsson,
Axel R. Persson,
Björn Hult,
Niklas Rorsman,
Vallery Stanishev,
Son Phuong Le,
Per O. Å. Persson,
Muhammad Nawaz,
Jr-Tai Chen,
Plamen P. Paskov,
Vanya Darakchieva
Abstract:
The hot-wall metal-organic chemical vapor deposition (MOCVD), previously shown to enable superior III-nitride material quality and high performance devices, has been explored for Mg doping of GaN. We have investigated the Mg incorporation in a wide doping range ($2.45\times{10}^{18}~cm^{-3}$ up to $1.10\times{10}^{20}~cm^{-3}$) and demonstrate GaN:Mg with low background impurity concentrations und…
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The hot-wall metal-organic chemical vapor deposition (MOCVD), previously shown to enable superior III-nitride material quality and high performance devices, has been explored for Mg doping of GaN. We have investigated the Mg incorporation in a wide doping range ($2.45\times{10}^{18}~cm^{-3}$ up to $1.10\times{10}^{20}~cm^{-3}$) and demonstrate GaN:Mg with low background impurity concentrations under optimized growth conditions. Dopant and impurity levels are discussed in view of Ga supersaturation which provides a unified concept to explain the complexity of growth conditions impact on Mg acceptor incorporation and compensation. The results are analysed in relation to the extended defects, revealed by scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), and surface morphology, and in correlation with the electrical properties obtained by Hall effect and capacitance-voltage (C-V) measurements. This allows to establish a comprehensive picture of GaN:Mg growth by hot-wall MOCVD providing guidance for growth parameters optimization depending on the targeted application. We show that substantially lower H concentration as compared to Mg acceptors can be achieved in GaN:Mg without any in-situ or post-growth annealing resulting in p-type conductivity in as-grown material. State-of-the-art $p$-GaN layers with a low-resistivity and a high free-hole density (0.77 $Ω$.cm and $8.4\times{10}^{17}~cm^{-3}$, respectively) are obtained after post-growth annealing demonstrating the viability of hot-wall MOCVD for growth of power electronic device structures.
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Submitted 28 February, 2022;
originally announced February 2022.
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Testing real quantum theory in an optical quantum network
Authors:
Zheng-Da Li,
Ya-Li Mao,
Mirjam Weilenmann,
Armin Tavakoli,
Hu Chen,
Lixin Feng,
Sheng-Jun Yang,
Marc-Olivier Renou,
David Trillo,
Thinh P. Le,
Nicolas Gisin,
Antonio Acín,
Miguel Navascués,
Zizhu Wang,
Jingyun Fan
Abstract:
Quantum theory is commonly formulated in complex Hilbert spaces. However, the question of whether complex numbers need to be given a fundamental role in the theory has been debated since its pioneering days. Recently it has been shown that tests in the spirit of a Bell inequality can reveal quantum predictions in entanglement swapping scenarios that cannot be modelled by the natural real-number an…
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Quantum theory is commonly formulated in complex Hilbert spaces. However, the question of whether complex numbers need to be given a fundamental role in the theory has been debated since its pioneering days. Recently it has been shown that tests in the spirit of a Bell inequality can reveal quantum predictions in entanglement swapping scenarios that cannot be modelled by the natural real-number analog of standard quantum theory. Here, we tailor such tests for implementation in state-of-the-art photonic systems. We experimentally demonstrate quantum correlations in a network of three parties and two independent EPR sources that violate the constraints of real quantum theory by over $4.5$ standard deviations, hence disproving real quantum theory as a universal physical theory.
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Submitted 30 November, 2021;
originally announced November 2021.
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Quantum Fokker-Planck Modeling of Degenerate Electrons
Authors:
H. P. Le
Abstract:
An implicit and conservative numerical scheme is proposed for the isotropic quantum Fokker-Planck equation describing the evolution of degenerate electrons subject to elastic collisions with other electrons and ions. The electron-ion and electron-electron collision operators are discretized using a discontinuous Galerkin method, and the electron energy distribution is updated by an implicit time i…
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An implicit and conservative numerical scheme is proposed for the isotropic quantum Fokker-Planck equation describing the evolution of degenerate electrons subject to elastic collisions with other electrons and ions. The electron-ion and electron-electron collision operators are discretized using a discontinuous Galerkin method, and the electron energy distribution is updated by an implicit time integration method. The numerical scheme is designed to satisfy all conservation laws exactly. Numerical tests and comparisons with other modeling approaches are shown to demonstrate the accuracy and conservation properties of the proposed method.
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Submitted 20 February, 2021;
originally announced February 2021.
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Comparison of ablators for the polar direct drive exploding pusher platform
Authors:
Heather D. Whitley,
G. Elijah Kemp,
Charles Yeamans,
Zachary Walters,
Brent E. Blue,
Warren Garbett,
Marilyn Schneider,
R. Stephen Craxton,
Emma M. Garcia,
Patrick W. McKenty,
Maria Gatu-Johnson,
Kyle Caspersen,
John I. Castor,
Markus Däne,
C. Leland Ellison,
James Gaffney,
Frank R. Graziani,
John Klepeis,
Natalie Kostinski,
Andrea Kritcher,
Brandon Lahmann,
Amy E. Lazicki,
Hai P. Le,
Richard A. London,
Brian Maddox
, et al. (14 additional authors not shown)
Abstract:
We examine the performance of pure boron, boron carbide, high density carbon, and boron nitride ablators in the polar direct drive exploding pusher (PDXP) platform. The platform uses the polar direct drive configuration at the National Ignition Facility to drive high ion temperatures in a room temperature capsule and has potential applications for plasma physics studies and as a neutron source. Th…
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We examine the performance of pure boron, boron carbide, high density carbon, and boron nitride ablators in the polar direct drive exploding pusher (PDXP) platform. The platform uses the polar direct drive configuration at the National Ignition Facility to drive high ion temperatures in a room temperature capsule and has potential applications for plasma physics studies and as a neutron source. The higher tensile strength of these materials compared to plastic enables a thinner ablator to support higher gas pressures, which could help optimize its performance for plasma physics experiments, while ablators containing boron enable the possiblity of collecting addtional data to constrain models of the platform. Applying recently developed and experimentally validated equation of state models for the boron materials, we examine the performance of these materials as ablators in 2D simulations, with particular focus on changes to the ablator and gas areal density, as well as the predicted symmetry of the inherently 2D implosion.
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Submitted 30 December, 2020; v1 submitted 28 June, 2020;
originally announced June 2020.
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Balanced Detection in Femtosecond X-ray Absorption Spectroscopy to Reach the Ultimate Sensitivity Limit
Authors:
W. F. Schlotter,
M. Beye,
S. Zohar,
G. Coslovich,
G. L. Dakovski,
M. -F. Lin,
Y. Liu,
A. Reid,
S. Stubbs,
P. Walter,
K. Nakahara,
P. Hart,
P. S. Miedema,
L. LeGuyader,
K. Hofhuis,
Phu Tran Phong Le,
Johan E. ten Elshof,
H. Hilgenkamp,
G. Koster,
X. H. Verbeek,
S. Smit,
M. S. Golden,
H. A. Durr,
A. Sakdinawat
Abstract:
X-ray absorption spectroscopy (XAS) is a powerful and well established technique with sensitivity to elemental and chemical composition. Despite these advantages, its implementation has not kept pace with the development of ultrafast pulsed x-ray sources where XAS can capture femtosecond chemical processes. X-ray Free Electron Lasers (XFELs) deliver femtosecond, narrow bandwidth (…
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X-ray absorption spectroscopy (XAS) is a powerful and well established technique with sensitivity to elemental and chemical composition. Despite these advantages, its implementation has not kept pace with the development of ultrafast pulsed x-ray sources where XAS can capture femtosecond chemical processes. X-ray Free Electron Lasers (XFELs) deliver femtosecond, narrow bandwidth ($\frac{ΔE}{E} < 0.5\%$) pulses containing $\sim 10^{10}$ photons. However, the energy contained in each pulse fluctuates thus complicating pulse by pulse efforts to quantify the number of photons. Improvements in counting the photons in each pulse have defined the state of the art for XAS sensitivity. Here we demonstrate a final step in these improvements through a balanced detection method that approaches the photon counting shot noise limit. In doing so, we obtain high quality absorption spectra from the insulator-metal transition in VO$_2$ and unlock a method to explore dilute systems, subtle processes and nonlinear phenomena with ultrafast x-rays. The method is especially beneficial for x-ray light sources where integration and averaging are not viable options to improve sensitivity.
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Submitted 24 June, 2020;
originally announced June 2020.
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Influence of atomic kinetics on inverse Bremsstrahlung heating and non-local thermal transport
Authors:
H. P. Le,
M. Sherlock,
H. A. Scott
Abstract:
This paper describes a computational model that self-consistently combines physics of kinetic electrons and atomic processes in a single framework. The formulation consists of a kinetic Vlasov- Boltzmann-Fokker-Planck equation for free electrons and a non-Maxwellian collisional-radiative model for atomic state populations. We utilize this model to examine the influence of atomic kinetics on invers…
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This paper describes a computational model that self-consistently combines physics of kinetic electrons and atomic processes in a single framework. The formulation consists of a kinetic Vlasov- Boltzmann-Fokker-Planck equation for free electrons and a non-Maxwellian collisional-radiative model for atomic state populations. We utilize this model to examine the influence of atomic kinetics on inverse Bremsstrahlung (IB) heating and non-local thermal transport. We show that atomic kinetics affects non-linear IB absorption rates by further modifying the electron distribution in addition to laser heating. We also show that accurate modeling of non-local heat flow requires a self-consistent treatment of atomic kinetics, because the effective thermal conductivity strongly depends on the ionization balance of the plasma.
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Submitted 8 July, 2019; v1 submitted 20 June, 2019;
originally announced June 2019.
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Conservative Algorithms for Non-Maxwellian Plasma Kinetics
Authors:
H. P. Le,
J. -L. Cambier
Abstract:
We present a numerical model and a set of conservative algorithms for Non-Maxwellian plasma kinetics with inelastic collisions. These algorithms self-consistently solve for the time evolution of an isotropic electron energy distribution function interacting with an atomic state distribution function of an arbitrary number of levels through collisional excitation, deexcitation, as well as ionizatio…
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We present a numerical model and a set of conservative algorithms for Non-Maxwellian plasma kinetics with inelastic collisions. These algorithms self-consistently solve for the time evolution of an isotropic electron energy distribution function interacting with an atomic state distribution function of an arbitrary number of levels through collisional excitation, deexcitation, as well as ionization and recombination. Electron-electron collisions, responsible for thermalization of the electron distribution, are also included in the model. The proposed algorithms guarantee mass/charge and energy conservation in a single step, and is applied to the case of non-uniform gridding of the energy axis in the phase space of the electron distribution function. Numerical test cases are shown to demonstrate the accuracy of the method and its conservation properties.
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Submitted 16 November, 2017;
originally announced November 2017.
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On the lateral instability analysis of MEMS comb-drive electrostatic transducers
Authors:
Binh Duc Truong,
Cuong Phu Le,
Einar Halvorsen
Abstract:
This paper investigates the lateral pull-in effect of an in-plane overlap-varying transducer. The instability is induced by the translational and rotational displacements. Based on the principle of virtual work, the equilibrium conditions of force and moment in lateral directions are derived. The analytical solutions of the critical voltage, at which the pull-in phenomenon occurs, are developed wh…
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This paper investigates the lateral pull-in effect of an in-plane overlap-varying transducer. The instability is induced by the translational and rotational displacements. Based on the principle of virtual work, the equilibrium conditions of force and moment in lateral directions are derived. The analytical solutions of the critical voltage, at which the pull-in phenomenon occurs, are developed when considering only the translational stiffness or only the rotational stiffness of the mechanical spring. The critical voltage in general case is numerically determined by using nonlinear optimization techniques, taking into account the combined effect of translation and rotation. The effects of possible translational offsets and angular deviations to the critical voltage are modeled and numerically analyzed. The investigation is then the first time expanded to anti-phase operation mode and Bennet's doubler configuration of the two transducers.
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Submitted 25 September, 2017;
originally announced September 2017.
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Analysis of MEMS electrostatic energy harvesters electrically configured as voltage multipliers
Authors:
Binh Duc Truong,
Cuong Phu Le,
Einar Halvorsen
Abstract:
This paper presents the analysis of an efficient alternative interface circuit for MEMS electrostatic energy harvesters. It is entirely composed by diodes and capacitors. Based on modeling and simulation, the anti-phase gap-closing structure is investigated. We find that when configured as a voltage multiplier, it can operate at very low acceleration amplitudes. In addition, the allowed maximum vo…
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This paper presents the analysis of an efficient alternative interface circuit for MEMS electrostatic energy harvesters. It is entirely composed by diodes and capacitors. Based on modeling and simulation, the anti-phase gap-closing structure is investigated. We find that when configured as a voltage multiplier, it can operate at very low acceleration amplitudes. In addition, the allowed maximum voltage between electrodes is barely limited by the pull-in effect. The parasitic capacitance of the harvester and non-ideal characteristics of electronic components are taken into account. A lumped-model of the harvesting system has been implemented in a circuit simulator. Simulation results show that an output voltage of 22 V is obtained with 0.15 g input acceleration. The minimum necessary ratio between the maximum and minimum capacitances of the generators which allows operation of the circuit, can be lower than 2. This overcomes a crucial obstacle in low-power energy harvesting devices. A comparison between the voltage multiplier against other current topologies is highlighted. An advantage of the former over the latter is to generate much higher saturation voltage, while the minimum required initial bias and the minimum capacitance ratio in both cases are in the similar levels.
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Submitted 25 September, 2017;
originally announced September 2017.
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Theoretical analysis of electrostatic energy harvester configured as Bennet's doubler based on Q-V cycles
Authors:
Binh Duc Truong,
Cuong Phu Le,
Einar Halvorsen
Abstract:
This paper presents theoretical analysis of a MEMS electrostatic energy harvester configured as the Bennet's doubler. Steady-state operation of the doubler circuit can be approximated by a right-angled trapezoid Q-V cycle. A similarity between voltage doubler and resistive-based charge-pump circuit is highlighted. By taking electromechanical coupling into account, the analytical solution of the sa…
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This paper presents theoretical analysis of a MEMS electrostatic energy harvester configured as the Bennet's doubler. Steady-state operation of the doubler circuit can be approximated by a right-angled trapezoid Q-V cycle. A similarity between voltage doubler and resistive-based charge-pump circuit is highlighted. By taking electromechanical coupling into account, the analytical solution of the saturation voltage is the first time derived, providing a greater comprehension of the system performance and multi-parameter effects. The theoretical approach is verified by results of circuit simulation for two cases of mathematically idealized diode and of Schottky diode. Development of the doubler/multiplier circuits that can further increase the saturation voltage is investigated.
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Submitted 25 September, 2017;
originally announced September 2017.
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Modeling of Inelastic Collisions in a Multifluid Plasma: Ionization and Recombination
Authors:
H. P. Le,
J. -L. Cambier
Abstract:
A model for ionization and recombination collisions in a multifluid plasma is formulated using the framework introduced in previous work [{Phys. Plasmas} \textbf{22}, 093512 (2015)]. The exchange source terms for density, momentum and energy are detailed for the case of electron induced ionization and three body recombination collisions with isotropic scattering. The principle of detailed balance…
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A model for ionization and recombination collisions in a multifluid plasma is formulated using the framework introduced in previous work [{Phys. Plasmas} \textbf{22}, 093512 (2015)]. The exchange source terms for density, momentum and energy are detailed for the case of electron induced ionization and three body recombination collisions with isotropic scattering. The principle of detailed balance is enforced at the microscopic level. We describe how to incorporate the standard collisional-radiative model into the multifluid equations using the current formulation. Numerical solutions of the collisional-radiative rate equations for atomic hydrogen are presented to highlight the impact of the multifluid effect on the kinetics.
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Submitted 20 May, 2016;
originally announced May 2016.
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Modeling of Inelastic Collisions in a Multifluid Plasma: Excitation and Deexcitation
Authors:
H. P. Le,
J. -L. Cambier
Abstract:
We describe here a model for inelastic collisions for electronic excitation and deexcitation processes in a general, multifluid plasma. The model is derived from kinetic theory, and applicable to any mixture and mass ratio. The principle of detailed balance is strictly enforced, and the model is consistent with all asymptotic limits. The results are verified with direct Monte Carlo calculations, a…
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We describe here a model for inelastic collisions for electronic excitation and deexcitation processes in a general, multifluid plasma. The model is derived from kinetic theory, and applicable to any mixture and mass ratio. The principle of detailed balance is strictly enforced, and the model is consistent with all asymptotic limits. The results are verified with direct Monte Carlo calculations, and various numerical tests are conducted for the case of an electron-hydrogen two-fluid system, using a generic, semi-classical model of collision cross sections. We find that in some cases, the contribution of inelastic collisions to the momentum and thermal resistance coefficients is not negligible, in contrast to the assumptions of current multifluid models. This fundamental model is also applied to ionization and recombination processes, the studies on which are currently underway.
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Submitted 2 September, 2015;
originally announced September 2015.
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The T2K ND280 Off-Axis Pi-Zero Detector
Authors:
S. Assylbekov,
B. E. Berger,
H. Berns,
D. Beznosko,
A. Bodek,
R. Bradford,
N. Buchanan,
H. Budd,
Y. Caffari,
K. Connolly,
I. Danko,
R. Das,
S. Davis,
M. Day,
S. Dytman,
M. Dziomba,
R. Flight,
D. Forbush,
K. Gilje,
D. Hansen,
J. Hignight,
J. Imber,
R. A. Johnson,
C. K. Jung,
V. Kravtsov
, et al. (31 additional authors not shown)
Abstract:
The Pi-Zero detector (PØD) is one of the subdetectors that makes up the off-axis near detector for the Tokai-to-Kamioka (T2K) long baseline neutrino experiment. The primary goal for the PØD is to measure the relevant cross sections for neutrino interactions that generate pi-zero's, especially the cross section for neutral current pi-zero interactions, which are one of the dominant sources of backg…
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The Pi-Zero detector (PØD) is one of the subdetectors that makes up the off-axis near detector for the Tokai-to-Kamioka (T2K) long baseline neutrino experiment. The primary goal for the PØD is to measure the relevant cross sections for neutrino interactions that generate pi-zero's, especially the cross section for neutral current pi-zero interactions, which are one of the dominant sources of background to the electron neutrino appearance signal in T2K. The PØD is composed of layers of plastic scintillator alternating with water bags and brass sheets or lead sheets and is one of the first detectors to use Multi-Pixel Photon Counters (MPPCs) on a large scale.
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Submitted 28 June, 2012; v1 submitted 21 November, 2011;
originally announced November 2011.
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Measurements of the T2K neutrino beam properties using the INGRID on-axis near detector
Authors:
K. Abe,
N. Abgrall,
Y. Ajima,
H. Aihara,
J. B. Albert,
C. Andreopoulos,
B. Andrieu,
M. D. Anerella,
S. Aoki,
O. Araoka,
J. Argyriades,
A. Ariga,
T. Ariga,
S. Assylbekov,
D. Autiero,
A. Badertscher,
M. Barbi,
G. J. Barker,
G. Barr,
M. Bass,
M. Batkiewicz,
F. Bay,
S. Bentham,
V. Berardi,
B. E. Berger
, et al. (407 additional authors not shown)
Abstract:
Precise measurement of neutrino beam direction and intensity was achieved based on a new concept with modularized neutrino detectors. INGRID (Interactive Neutrino GRID) is an on-axis near detector for the T2K long baseline neutrino oscillation experiment. INGRID consists of 16 identical modules arranged in horizontal and vertical arrays around the beam center. The module has a sandwich structure o…
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Precise measurement of neutrino beam direction and intensity was achieved based on a new concept with modularized neutrino detectors. INGRID (Interactive Neutrino GRID) is an on-axis near detector for the T2K long baseline neutrino oscillation experiment. INGRID consists of 16 identical modules arranged in horizontal and vertical arrays around the beam center. The module has a sandwich structure of iron target plates and scintillator trackers. INGRID directly monitors the muon neutrino beam profile center and intensity using the number of observed neutrino events in each module. The neutrino beam direction is measured with accuracy better than 0.4 mrad from the measured profile center. The normalized event rate is measured with 4% precision.
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Submitted 14 November, 2011;
originally announced November 2011.
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Development of a Flow Solver with Complex Kinetics on the Graphic Processing Units
Authors:
H. P. Le,
J. -L. Cambier
Abstract:
The current paper reports on the implementation of a numerical solver on the Graphic Processing Units (GPU) to model reactive gas mixture with detailed chemical kinetics. The solver incorporates high-order finite volume methods for solving the fluid dynamical equations coupled with stiff source terms. The chemical kinetics are solved implicitly via an operator-splitting method. We explored differe…
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The current paper reports on the implementation of a numerical solver on the Graphic Processing Units (GPU) to model reactive gas mixture with detailed chemical kinetics. The solver incorporates high-order finite volume methods for solving the fluid dynamical equations coupled with stiff source terms. The chemical kinetics are solved implicitly via an operator-splitting method. We explored different approaches in implementing a fast kinetics solver on the GPU. The detail of the implementation is discussed in the paper. The solver is tested with two high-order shock capturing schemes: MP5 (Suresh, et al. (1997)) and ADERWENO (Titarev, et al. (2005)). Considering only the fluid dynamics calculation, the speed-up factors obtained are 30 for the MP5 scheme and 55 for ADERWENO scheme. For the fully-coupled solver, the performance gain depended on the size of the reaction mechanism. Two different examples of chemistry were explored. The first mechanism consisted of 9 species and 38 reactions, resulting in a speed-up factor up to 35. The second, larger mechanism consisted of 36 species and 308 reactions, resulting in a speed-up factor of up to 40.
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Submitted 21 October, 2011;
originally announced October 2011.
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The T2K Experiment
Authors:
T2K Collaboration,
K. Abe,
N. Abgrall,
H. Aihara,
Y. Ajima,
J. B. Albert,
D. Allan,
P. -A. Amaudruz,
C. Andreopoulos,
B. Andrieu,
M. D. Anerella,
C. Angelsen,
S. Aoki,
O. Araoka,
J. Argyriades,
A. Ariga,
T. Ariga,
S. Assylbekov,
J. P. A. M. de André,
D. Autiero,
A. Badertscher,
O. Ballester,
M. Barbi,
G. J. Barker,
P. Baron
, et al. (499 additional authors not shown)
Abstract:
The T2K experiment is a long-baseline neutrino oscillation experiment. Its main goal is to measure the last unknown lepton sector mixing angle θ_{13} by observing ν_e appearance in a ν_μ beam. It also aims to make a precision measurement of the known oscillation parameters, Δm^{2}_{23} and sin^{2} 2θ_{23}, via ν_μ disappearance studies. Other goals of the experiment include various neutrino cross…
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The T2K experiment is a long-baseline neutrino oscillation experiment. Its main goal is to measure the last unknown lepton sector mixing angle θ_{13} by observing ν_e appearance in a ν_μ beam. It also aims to make a precision measurement of the known oscillation parameters, Δm^{2}_{23} and sin^{2} 2θ_{23}, via ν_μ disappearance studies. Other goals of the experiment include various neutrino cross section measurements and sterile neutrino searches. The experiment uses an intense proton beam generated by the J-PARC accelerator in Tokai, Japan, and is composed of a neutrino beamline, a near detector complex (ND280), and a far detector (Super-Kamiokande) located 295 km away from J-PARC. This paper provides a comprehensive review of the instrumentation aspect of the T2K experiment and a summary of the vital information for each subsystem.
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Submitted 8 June, 2011; v1 submitted 6 June, 2011;
originally announced June 2011.