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Observation of partonic flow in proton-proton and proton-nucleus collisions
No full textInternational audienceQuantum Chromodynamics predicts a phase transition from ordinary hadronic matter to the quark-gluon plasma (QGP) at high temperatures and energy densities, where quarks and gluons (partons) are not confined within hadrons. The QGP is generated in ultrarelativistic heavy-ion collisions. Anisotropic flow coefficients, quantifying the anisotropic azimuthal expansion of the produced matter, provide a unique tool to unravel QGP properties. Flow measurements in high-energy heavy-ion collisions show a distinctive grouping of anisotropic flow for baryons and mesons at intermediate transverse momentum, a feature associated with flow being imparted at the quark level, confirming the existence of the QGP. The observation of QGP-like features in relativistic proton-proton and proton-ion collisions has sparked debate about possible QGP formation in smaller collision systems, which remains unresolved. In this article, we demonstrate for the first time the distinctive grouping of anisotropic flow for baryons and mesons in high-multiplicity proton-lead and proton-proton collisions at the Large Hadron Collider (LHC). These results are described by a model that includes hydrodynamic flow followed by hadron formation via quark coalescence, replicating features observed in heavy-ion collisions. This observation is consistent with the formation of a partonic flowing system in proton-proton and proton-lead collisions at the LHC
Non-cyclic prototype of JUNO-TAO VETO water tank with 3 inch PMTs
No full textInternational audienceThe Taishan Antineutrino Observatory (TAO, also known as JUNO-TAO) is a satellite experiment of the Jiangmen Underground Neutrino Observatory (JUNO). A ton-level liquid scintillator detector will be placed at about 30 m from a core of the Taishan Nuclear Power Plant. The reactor antineutrino spectrum will be measured with sub-percent energy resolution, to provide a reference spectrum for future reactor neutrino experiments, and to provide a benchmark measurement to test nuclear databases. A Cerenkov water tank system with a thickness of 1.2 m pure water will be located around the central detector of TAO. The water tank system designed with 300 3" PMTs (SPMT) will use the same electronics as JUNO SPMT, but with online software multiplicity trigger. The performance of a Cerenkov detector with the JUNO SPMT and electronics designed for liquid scintillator detector needs to be checked, including the software triggering. The features and the long stability of the detector without water circulation also needs to be checked as a common concern and a backup option for future JUNO-TAO running. Here we will summary the integration and testing of a prototype water tank detector system, including SPMT, electronics, data taking, simulation and measurement results
Systèmes MIMO pour les communications acoustiques sous-marines à haute efficacité spectrale
No full textLa liste des symboles est manquante. En attendant la correction de la version HAL, la version complète est disponible sur demande auprès de l'auteur ou sur ResearchGate.In the context of increasing dronization of underwater systems, the ability to communicate undersea responds to growing stakes for mastering the seabed. The underwater acoustic channels is a harsh medium for communications, where the limited available bandwidth and channel selectivity limit the data rates. In this thesis, the use of MIMO techniques is proposed, aiming data rates of order of the hundred of kilobits per second. Based on existing SISO models, a MIMO model of the underwater acoustic channel is proposed. Its channel capacity, as well as the impact of spatial coherence on the design of communication systems, is examined. Subsequently, a channel estimation method, based on compressed sensing, is proposed. Helped with the underwater acoustic channel sparsity, the robustness of the communication to channel fluctuations with time is improved, while the use of pilots symbols is limited, increasing the data rate. The combination of this method with interference cancellation in order to perform decision directed channel estimation, also enabling higher data rates, is also envisaged. Finally, experimental results, obtained in an underwater medium, are presented: they confirm the feasibility of the proposed methods.Dans un contexte de dronisation des systèmes, la capacité à communiquer en milieu sous-marin répond à des enjeux croissants de maîtrise des fonds marins. Le canal acoustique sous-marin reste difficile : les débits sont limités par les faibles bandes de fréquences utilisables et la sélectivité du canal. Dans cette thèse, on propose l’utilisation de techniques MIMO pour atteindre des débits de l’ordre de la centaine de kilobits par seconde. Partant des modèles existant en SISO,un modèle MIMO du canal acoustique sous-marin est proposé. Sa capacité, ainsi que l’impact de la cohérence spatiale du canal sur le dimensionnement des systèmes, sont étudiés. Par la suite, une méthode d’estimation de canal, basée sur l’acquisition compressée, est proposée. Grâce à la parcimonie du canal acoustique sous-marin, on peut alors d’une part améliorer la robustesse de la communication face aux fluctuations temporelles du canal, et d’autre part limiter l’utilisation de pilotes et ainsi augmenter les débits réalisés. La combinaison de cette méthode avec des techniques d’annulation d’interférences pour réaliser une estimation de canal basée sur les décisions est également proposée, permettant là encore des débits plus élevés. Enfin, des résultats expérimentaux, obtenus en milieu sous-marin, sont présentés : ils confirment la faisabilité des différentes méthodes proposées
TENSLORA: TENSOR ALTERNATIVES FOR LOW-RANK ADAPTATION
No full textInternational audienceLow-Rank Adaptation (LoRA) is widely used to efficiently adapt Transformers by adding trainable low-rank matrices to attention projections. While effective, these matrices are considered independent for each attention projection (Query, Key, and Value) and each layer. Recent extensions have considered joint, tensor-based adaptations, but only in limited forms and without a systematic framework. We introduce TensLoRA, a unified framework that aggregates LoRA updates into higher-order tensors and models a broad family of tensor-based low-rank adaptations. Our formulation generalizes existing tensor-based methods and enables modespecific compression rates, allowing parameter budgets to be tailored according to the modality and task. Experiments on vision and language benchmarks reveal that the tensor construction directly impacts performance, sometimes better than standard LoRA under similar parameter counts
Optimisation des plannings hospitaliers du personnel non médical pendant la phase opérationnelle offline
No full textNational audienceOptimisation des plannings hospitaliers du personnel non médical pendant la phase opérationnelle offlin
Planification optimisée des livraisons d'hydrogène par conteneur de stockage mobile
No full textNational audienc
GWTC-4.0: Population Properties of Merging Compact Binaries
No full textInternational audienceWe detail the population properties of merging compact objects using 158 mergers from the cumulative Gravitational-Wave Transient Catalog 4.0, which includes three types of binary mergers: binary neutron star, neutron star--black hole binary, and binary black hole mergers. We resolve multiple over- and under-densities in the black hole mass distribution: features persist at primary masses of and with a possible third feature at . These are departures from an otherwise power-law-like continuum that steepens above . Binary black holes with primary masses near are more likely to have less massive secondaries, with a mass ratio distribution peaking at , potentially a signature of stable mass transfer during binary evolution. Black hole spins are inferred to be non-extremal, with 90% of black holes having , and preferentially aligned with binary orbits, implying many merging binaries form in isolation. However, we find a significant fraction, 0.24-0.42, of binaries have negative effective inspiral spins, suggesting many could be formed dynamically in gas-free environments. We find evidence for correlation between effective inspiral spin and mass ratio, though it is unclear if this is driven by variation in the mode of the distribution or the width. (Abridged
Multi-period replenishment planning with supplier assignment under a dynamic demand and stochastic lead-times
No full textInternational audienceWe consider a multi-period replenishment planning problem with dynamic demand and multiple suppliers. Each supplier has its own selling price and random lead time. The objective is to decide how the demands for different periods are distributed among the pre-selected suppliers while minimising the expected total cost, which comprises holding and backlogging costs, as well as the selling price. This statement highlights the trade-off between supplier prices and uncertain lead times in replenishment planning. Two scenario-based stochastic programmes, one linear and one non-linear, are provided to simultaneously consider dispatching orders between suppliers, order crossover, and order release flexibility. The non-linear model, which relies on power sets to reduce the number of aggregated scenarios, is coupled with two approximate solution methods. The numerical experiments prove the computational effectiveness of the non-linear model. These results can be helpful for decision-makers when negotiating prices with suppliers. For instance, we can determine the purchasing cost at which we order almost 100% from a given supplier. If we now turn to the uncertainty of lead times, this study can also help negotiate with suppliers whose firms cannot decrease their selling prices and advise them, thereby reducing the variance of their lead times
Constraints on Solar Reflected Dark Matter from a combined analysis of XENON1T and XENONnT data
No full textInternational audienceWe report on a search for sub-GeV dark matter upscattered via the solar reflection mechanism in the heavy mediator scenario. Under the Standard Halo Model, keV to MeV dark matter produces nuclear recoils with energies below the detection threshold of liquid xenon time projection chambers. We enhance sensitivity to low-mass dark matter by considering dark matter-electron scattering, employing dedicated event selections to reduce the detection threshold, and exploiting the additional kinetic energy imparted to the dark matter particle by solar upscattering. Using XENON1T ionization-only and XENONnT low-energy electronic recoil datasets, we exclude previously unconstrained DM-electron scattering cross section for masses between and , and between and , reaching a minimum of for a mass of at 90% confidence level
Characterization of CRYO ASIC for charge readout in the nEXO experiment
No full textInternational audiencenEXO is a proposed next-generation experiment searching for the neutrinoless double beta decay of Xe using a tonne-scale liquid xenon (LXe) time projection chamber (TPC). To image the ionization signals from events in the liquid xenon, the detector will employ metallized fused-silica charge collection tiles instrumented with cryogenic application-specific integrated circuits (ASICs), referred to as CRYO ASIC, which are designed to operate directly in LXe to minimize input capacitance and pick-up noise. Here we present the performance of the CRYO ASIC mounted on an auxiliary printed circuit board and evaluated both in a cryogenic environmental chamber and in a dedicated LXe test stand. We demonstrate that the ASICs achieve the desired performance at liquid xenon temperatures, showing a gain stability better than 0.2% over 24-hour operation and reliable in-situ calibration using an on-chip pulser. In the LXe test stand, we show that boiling caused by the chip heat dissipation can be mitigated by operating the system above ~0.1 MPa. The in-LXe noise measured agrees with simulation, which indicates it the design requirement can be satisfied. These results establish CRYO ASIC as a viable low-noise in-LXe charge readout solution for nEXO