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Spatial resolution studies with the BabyIAXO Micromegas prototype
No full textInternational audienceThe spatial resolution of the Micromegas prototype developed for the BabyIAXO experiment was evaluated using a low-energy X-ray beam at the SOLEIL synchrotron facility. BabyIAXO, currently under construction, aims to search for hypothetical solar axions. A key component of the experiment is a low-background X-ray detector with high efficiency in the 1-10 keV energy range and stringent background rejection capabilities. Achieving a spatial resolution on the order of, or better than, 1 mm is critical for accurately reconstructing signal shapes and positions, and for effectively discriminating between signal and background events. Therefore, a precise characterization of the detector's spatial resolution is essential to validate its suitability for the experiment. This study involved scanning the IAXO-D1 Micromegas detector under various beam energies, positions, and drift field configurations to evaluate their influence on spatial resolution. A resolution of approximately 100 m at 6 keV was achieved, confirming the strong potential of this technology for application in the final BabyIAXO setup
AI-enabled spectral classification of plastic resins from E-waste via laser-induced breakdown spectroscopy for advanced sorting applications
No full textInternational audienceIn the framework of the circular economy (CE), efficient waste segregation is essential for sustainable recycling. Plastic waste from waste electrical and electronic equipment (WEEE) poses challenges due to complex resin structures and the presence of brominated flame retardants (BFRs). This study investigates the use of laserinduced breakdown spectroscopy (LIBS) combined with supervised machine learning (ML) for the classification of various e-waste plastics, including mixed resins and those containing BFRs. Although the primary analysis was conducted using static LIBS data, dynamic tests were also performed to simulate real-world sorting conditions. Among the classifiers, Support Vector Machine (SVM) and Neural Network Multilayer Perceptron (NNMLP) delivered the best results, reaching 92-94 % accuracy on test data and up to 96 % on unseen datasets. Furthermore, dynamic trials showed over 98 % accuracy, confirming the robustness of the approach. These findings highlight the potential of LIBS-ML systems for scalable, high-precision sorting, advancing industrial recycling strategies
VENDETA: VErsatile Neutron DETector Array, a new high-resolution neutron time-of-flight measurement array
No full textInternational audienceThe VErsatile Neutron DETector Array (VENDETA) is a high-resolution time-of-flight array for neutron detection. VENDETA’s liquid scintillator detectors offer a high intrinsic efficiency for neutron detection from 100keV to 20MeV, as well as neutron-γ discrimination capabilities down to 10keVee. VENDETA was specifically designed for versatility and is relevant for a wide range of physics measurements, from prompt fission neutron spectra measurements to neutron spectroscopy studies, such as elastic and inelastic neutron scattering measurements. VENDETA was first deployed at the Los Alamos Neutron Science Center. This article will provide a detailed overview of its characteristics
Characterization of the Electronic Noise in the Readout of Resistive Micromegas in the High-Angle Time Projection Chambers of the T2K Experiment
No full textInternational audienceThe two high-angle Time Projection Chambers of the T2K experiment are equipped with a new readout system based on resistive Micromegas detector technology, and utilize custom-made electronics based on AFTER chips for signal processing. This study analyzes and characterizes the electronic noise of the detector readout chain to develop a comprehensive noise model. The model enables the generation of Monte Carlo simulations to investigate systematic effects in signal processing. The analysis is based on data collected from 32 resistive Micromegas detectors, recorded without zero suppression. All detectors exhibit a quasi-identical and time-stable noise level. The developed analytical model accurately describes the observed noise, and derived Monte Carlo simulations show excellent agreement with experimental data
Measurements of the inclusive W and Z boson production cross sections and their ratios in proton-proton collisions at = 13.6 TeV
No full textInternational audienceMeasurements are presented of the W and Z boson production cross sections in proton-proton collisions at a center-of-mass energy of 13.6 TeV. Data collected in 2022 and corresponding to an integrated luminosity of 5.01 fb with one or two identified muons in the final state are analyzed. The results for the products of total inclusive cross sections and branching fractions for muonic decays of W and Z bosons are 11.93 0.08 (syst) 0.17 (lumi) (acc) nb for W boson production, 8.86 0.06 (syst) 0.12 (lumi) (acc) nb for W boson production, and 2.021 0.009 (syst) 0.028 (lumi) (acc) nb for the Z boson production in the dimuon mass range of 60-120 GeV, all with negligible statistical uncertainties. Furthermore, the corresponding fiducial cross sections, as well as cross section ratios for both fiducial and total phase space, are provided. The ratios include charge-separated results for W boson production (W and W) and the sum of the two contributions (W), each relative to the measured Z boson production cross section. Additionally, the ratio of the measured cross sections for W and W boson production is reported. All measurements are in agreement with theoretical predictions, calculated at next-to-next-to-leading order accuracy in quantum chromodynamics
Quantum vs. semiclassical description of in-QGP quarkonia in the quantum Brownian regime
No full textInternational audienceIn this work, we explore the range of validity of the semiclassical approximation of a quantum master equation designed to describe the dynamics in a quark gluon plasma at various temperatures, in the quantum Brownian regime. We perform a comparative study of various properties, e.g. the charmonia yield, of the Wigner density obtained with the Lindblad equation and with the associated semiclassical Fokker-Planck equation. The semiclassical description is found to reproduce with a remarkable accuracy the results obtained through the full quantum description. We show that, to a large extent, this can be attributed to the non-unitary components of the dynamics that result from the contact of the subsystem with the thermal bath, leading to a rapid classicalization of the subsystem
Design, simulation and performance of the resistive-anode PICOSEC Micromegas detector
No full textInternational audienceThe PICOSEC Micromegas detector is a Micro-Pattern Gaseous Detector concept developed to achieve tens of picosecond timing resolution for charged particle detection by combining a Cherenkov radiator with a two-stage Micromegas amplification structure. To improve operational robustness, a resistive anode has been implemented using a DLC layer deposited on a Kapton substrate. While this design enhances detector stability, the resistive layer may influence rate capability, signal formation, and detector capacitance, altering timing performance. This work presents a comprehensive study of a resistive design, including an analytical model and finite-element simulations to quantify rate-dependent gain reduction due to ohmic voltage drop on the resistive layer. An analytical solution for the voltage across a finite-size resistive layer is derived, and a numerical model is developed to evaluate gain suppression under intense particle fluxes. The impact of the resistive layer on signal formation is investigated using time-dependent weighting fields and the Garfield++ simulation framework. The contribution of signal components induced by the resistive layer is quantified, and preservation of the signal leading edge is found for surface resistivities above 100 kohm per square. Single-channel resistive-anode prototypes were designed, constructed, and experimentally characterized. Laboratory measurements using single photoelectrons and power spectral density analysis show the predicted reduction in signal amplitude while preserving the leading edge. Muon beam tests with CsI and DLC photocathodes demonstrate a time resolution of 11.5 ps for CsI, comparable to 11.9 ps for the metallic-anode device, showing the suitability of the resistive design for precision timing applications
Finite-resolution measurement induces topological curvature defects in spacetime
No full textWe show that regularizing (2 + 1)-dimensional Minkowski spacetime with a finite-resolution Gaussian probe, analogous to Weyl-Heisenberg (Gabor) signal analysis and related quantization, induces a curved geometry with a topological defect. The regularized metric replaces r 2 by r 2 + σ 2 in the angular part, where σ is the resolution scale from the width of the Gaussian probe. The resulting Gaussian curvature integrates to -2π, independently of σ, and including the boundary contribution, yields Euler characteristic χ = 0, corresponding to a punctured plane. This curvature defines an effective stress-energy source with total energy E eff = -1/(4G), universal and σ-independent. Spatial slices embed isometrically as helicoids, and geodesics exhibit a characteristic swirling motion. These results show that finite spatial resolution measurement does not merely smooth singularities but imprints topological defects with fixed physical consequences, suggesting that observational limitations fundamentally shape spacetime geometry. We show how our Gabor regularisation is extendable to (3 + 1) Minkowski space-time
Low-redshift 3D Lyman-α Forest Correlations with China Space Station Telescope
No full textInternational audienceWhile the Lyman- (Ly) forest traces the large-scale matter distribution over a wide range of redshift, its three-dimensional (3D) clustering at has not yet been measured. We investigate the prospects for measuring low-redshift Ly correlations with the UV slitless spectroscopic instrument of the China Space Station Telescope (CSST). We construct mock CSST quasar spectra that reproduce the expected survey depth, spectral resolution and noise properties, and derive Ly auto-correlation functions and cross-correlations with quasars (QSO) and emission-line galaxies (ELG) in the range . We then interpret these three-dimensional correlation functions with a standard anisotropic redshift-space clustering model and obtain forecast constraints on the Ly and tracer parameters. At an effective redshift (1.58 for ELGs), the Ly bias parameters will be measured with a 10-30% precision, depending on priors on other tracer's biases. We also forecast a marginal () detection of the BAO feature, corresponding to a 10% (7%) constraint on the isotropic BAO scale, from the combination of Ly auto- and Ly-QSO (ELG) cross-correlations. These results show that CSST can provide the first three-dimensional characterization of the low-redshift Ly forest and a complementary Ly-based BAO measurement at , helping to link galaxy clustering surveys with high-redshift Ly forest studies
ESO Expanding Horizon White Paper: Revealing the properties of matter at supranuclear densities with gravitational waves
No full textInternational audienceUnderstanding dense matter under extreme conditions is one of the most fundamental puzzles in modern physics. Complex interactions give rise to emergent, collective phenomena. While nuclear experiments and Earth - based colliders provide valuable insights, much of the quantum chromodynamics phase diagram at high density and low temperature remains accessible only through astrophysical observations of neutron stars, neutron star mergers, and stellar collapse. Astronomical observations thus offer a direct window to the physics on subatomic scales with gravitational waves presenting an especially clean channel. Next-generation gravitational - wave observatories, such as the Einstein Telescope, would serve as unparalleled instruments to transform our understanding of neutron star matter. They will enable the detection of up to tens of thousands of binary neutron star and neutron star - black hole mergers per year, a dramatic increase over the few events accessible with current detectors. They will provide an unprecedented precision in probing cold, dense matter during the binary inspiral, exceeding by at least an order of magnitude what current facilities can achieve. Moreover, these observatories will allow us to explore uncharted regimes of dense matter at finite temperatures produced in a subset of neutron star mergers, areas that remain entirely inaccessible to current instruments. Together with multimessenger observations, these measurements will significantly deepen our knowledge of dense nuclear matter