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, K, and p production in high-multiplicity pp collisions at TeV
No full textInternational audienceThis paper presents the measurement of , K, and p() production in high-multiplicity proton-proton collisions at TeV at midrapidity () using the ALICE detector at the LHC. The transverse-momentum () spectra of these particles are reported for three high-multiplicity classes. The results show a mass- and multiplicity-dependent hardening of the spectra and an enhancement of the p/ ratio at intermediate . These features are similar to those observed in heavy-ion collisions, where quark-gluon plasma formation is expected. The new measurements have extended the highest average charged-particle multiplicity density per unit of pseudorapidity achieved in pp collisions, roughly a factor five higher than that in average inelastic pp collisions, thereby reducing the multiplicity gap between small and large collision systems. In addition, the results are further compared with previously published measurements and with model calculations obtained using distinct tunes of the PYTHIA 8 Monte Carlo generator, as well as with predictions from the EPOS4. The comparison of the -integrated K/ and p/ ratios across different collision systems and energies suggests that particle production scales with charged-particle multiplicity, rather than with collision energy or system size. While the PYTHIA 8 tunes and the EPOS4 model are able to reproduce some of these measurements, either quantitatively or qualitatively, none of them consistently describes all observed features of the data
Elliptic flow of charm quarks produced in the early stage of <math display="inline"><mi>p</mi><mi>A</mi></math> collisions
No full textInternational audienceWe investigate the buildup of elliptic flow of charm quarks produced in the early pre-equilibrium stage of high-energy proton-nucleus collisions. The initial stage is modeled within the color glass condensate framework as an evolving glasma, initialized through the McLerran-Venugopalan model. Subnucleonic fluctuations have been implemented as constituent-quark hotspots for both the proton and the nuclear participants. Charm quarks are propagated in the evolving non-Abelian background by solving the relativistic Wong equations for their coordinates, momenta, and color charges. First, we compute the nuclear modification factor of charm quarks, finding a slight migration towards higher pT states in agreement with previous results in the literature. Then, we focus on the azimuthal anisotropies acquired through the interaction with glasma fields. We find that glasma-induced momentum anisotropies are efficiently transmitted to heavy quarks within τ∼0.4 fm/c, leading to a sizeable charm-quark v2, with a magnitude that increases with the strength of the initial fields and with the number of nuclear participants. Remarkably, we show that the early stage contribution alone can account for a significant fraction of the experimentally observed J/ψ elliptic flow in p-Pb collisions, indicating that prehydrodynamic dynamics can play a non-negligible role in the final-state heavy-flavor collectivity, especially in small systems
Synchronized DNA sources for unconditionally secure cryptography
No full textSecure communication is the cornerstone of modern infrastructures, yet achieving unconditional security -resistant to any computational attack- remains a fundamental challenge. The One-Time Pad (OTP), proven by Shannon to offer perfect secrecy, requires a shared random key as long as the message, used only once. However, distributing large keys over long distances has been impractical due to the lack of secure and scalable sharing options. Here, we introduce a DNA-based cryptographic primitive that leverages random pools of synthetic DNA to install a synchronized entropy source between distant parties. Our approach uses duplicated DNA molecules -comprising random index-payload pairs- as a shared secret. These molecules are locally sequenced and digitized to generate a common binary mask for OTP encryption, achieving unconditional security without relying on computational assumptions. We experimentally demonstrate this protocol between Tokyo and Paris, using in-house sequencing, generating a shared secret mask of 400 Mb with a residual error rate to achieve the usual overall decryption failure rate of 2-128 . The min-entropy of the binary mask meets the most recent National Institute of Standards and Technology requirements (SP 800-90B), and is comparable to that of approved cryptographic random number generators. Critically, our system can resist two types of adversarial interference through molecular copy-number statistics, providing an additional layer of security reminiscent of Quantum Key Distribution, but without distance limitations. This work establishes DNA as a scalable entropy source for long-distance OTP, enabling high-throughput and secure communications in sensitive contexts. By bridging molecular biology and cryptography, DNA-based key distribution opens a promising new route toward unconditional security in global communication networks
Penser l’ambivalence constructive : un levier pour l’appropriation de l’IA en santé
No full textInternational audienceArtificial Intelligence is increasingly integrated into healthcare innovative projects, while simultaneously eliciting both positive and negative judgements. The literature generally analyses this ambivalence as an obstacle to adoption or as a problem to be solved, using concepts such as dilemmas, paradoxes and organisational tensions. This article proposes a shift in analysis, approaching ambivalence not only as an individual experience or a barrier to innovation, but as a dynamic that can be regulated by organisational mechanisms. Based on a literature review and a study of recent empirical work, the article identifies and analyses three recurring tensions between: surveillance and care, standardisation and personalisation, and organisational constraints and professional autonomy. It shows that these tensions can become beneficial when they are recognised, organised and supported by appropriate governance mechanisms. The article thus introduces the concept of constructive ambivalence as a lever for the situated appropriation of AI in healthcare.L’Intelligence Artificielle occupe une place croissante dans les projets d’innovation en santé, tout en suscitant des jugements simultanément positifs et négatifs. La littérature analyse généralement cette ambivalence comme un obstacle à l’appropriation ou un problème à résoudre, via les notions de dilemmes, de paradoxes ou de tensions organisationnelles. Cet article propose un déplacement analytique en abordant l’ambivalence non plus seulement comme une expérience individuelle ou un frein à l’innovation, mais comme une dynamique susceptible d’être régulée par des dispositifs organisationnels. A partir d’une revue de littérature et l’étude de travaux empiriques récents l’article identifie et analyse trois tensions récurrentes entre : surveillance et care, standardisation et personnalisation, et contraintes organisationnelles et autonomie professionnelle. Il montre que ces tensions peuvent devenir bénéfiques lorsqu’elles sont reconnues, organisées et soutenues par des dispositifs de gouvernance adaptés. L’article introduit ainsi le concept d’ambivalence constructive comme levier d’appropriation située de l’IA en santé
Search for β-delayed fission of Aug,m178 and an updated systematics in the region of neutron-deficient nuclei
No full textInternational audienceA search for a β-delayed fission (βDF) decay branch of isomerically pure samples of 178 Augand 178 Aum has been performed at the ISOLDE-CERN facility. Two complementary detectionsystems capable of registering α decays and fission fragments, the ISOLDE Decay Station and theASET (Alpha SETup), were used. Despite very high statistics of produced 178 Au nuclei, no fissionfragments were detected. Upper limits of βDF probabilities of PβDF (178 Aug ) < 1.11(2) × 10−8 andPβDF (178 Aum ) < 9.7(2) × 10−9 were determined. Corresponding lower limits of βDF partial half-lives were deduced as well, and the results are discussed in the context of experimental systematicsof βDF in the neutron-deficient region of the nuclear chart
Proton beam monitoring through water scintillation in radiobiology experiments
No full textInternational audienceNon-invasive methods based on the detection of secondary particles generated in the irradiated medium are being investigated to monitor ion beams without disturbing the beam. This study investigates the use of water scintillation as a beam monitoring tool, taking into account the challenges posed by the radiobiology experiment constraints. An experimental setup has been designed to measure the depth deposited energy profile produced by protons of (67.5 ± 0.4) MeV entering a water tank, through the water scintillation detected with a photomultiplier. The beam current during the experiment was around 100 pA, and beam intensity fluctuations were monitored using a parallel plate ionization chamber and a Faraday cup. The experiment was repeated with a second ionization chamber as a reference detector placed inside the water tank, and simulated with the GATE Monte Carlo code. The position of the Bragg peak, measured with the water scintillation, shows significant agreement (deviation of 0.5 mm) with the positions obtained from the ionization chamber and the Monte Carlo simulation within a submillimeter uncertainty. The ionization quenching effect was also observed and corrected using the Birks and Chou models. A new value of the key parameter for these models (k · B = (8.0 ± 4.0) × 10−3 g/MeV.cm2) has been determined for water, which is in good agreement with the data available in the literature for organic scintillators. This study demonstrated the feasibility of using water scintillation measured with a collimated photomultiplier as a tool for monitoring the depth deposited energy profile in water. •Water scintillation is used to monitor proton beams in radiobiological experiment.•The Bragg peak is localized with submillimeter uncertainty.•The Chou model allows for correction of ionization quenching for water.•The Birks and Chou parameters were determined for water
Study on the equation-of-state with light clusters and hypernuclei
No full textInternational audienceHeavy-ion collision experiments offer a unique opportunity to explore the early stages of the Universe by creating matter under extreme conditions of high temperature and baryon density. The properties of such matter are governed by the equation-of-state (EoS), which remains a central focus of investigation from both experimental and theoretical perspectives. Flow harmonics are among the most sensitive observables for probing the EoS, as they strongly reflect the underlying interactions and degrees of freedom of the system. In this article, we review the current status of our understanding of the EoS based on microscopic transport models, emphasizing comparisons with experimental data in the few GeV energy range
production in pp collisions at TeV
No full textInternational audienceThe measurement of production in pp collisions at TeV is presented. The measurement is performed at midrapidity in both minimum-bias and high-multiplicity pp collisions at TeV. The is reconstructed via its weak-decay topology in the decay channel with . In a novel approach, the neutral pion is reconstructed by combining photons that convert in the detector material with photons measured in the calorimeters. The transverse-momentum () distributions of the and its rapidity densities ddy in both event classes are reported. The spectrum in minimum-bias collisions is compared to QCD-inspired event generators. The ratio of to previously measured baryons is in good agreement with calculations from the Statistical Hadronization Model. The high efficiency and purity of the novel reconstruction method for presented here will enable future studies of the interaction of with protons in the context of femtoscopic measurements, which could be crucial for understanding the equation of state of neutron stars
Flow in small systems in the EPOS4 approach for high-energy scatterings
No full textInternational audienceEPOS4 is based on a sophisticated (recently significantly improved) parallel-primary-scattering scenario followed by a hydrodynamic expansion, for all collision systems, from small ones such as proton-proton () to big ones such as lead-lead (PbPb). Having already reported on identified particle spectra in recent publications (providing information about radial flow), I discuss here the multiplicity dependence of multi-particle cumulants and flow harmonics, to better understand collectivity in small systems. The model is not particularly tuned for flow results, but it is a "general purpose" approach, trying to accommodate various types of observables with the same model