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    Production of light (anti)nuclei in pp collisions at s=5.02\sqrt{s} = 5.02 TeV

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    Springer Verlag (Germany)
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    International audienceThe study of the production of nuclei and antinuclei in pp collisions has proven to be a powerful tool to investigate the formation mechanism of loosely bound states in high-energy hadronic collisions. In this paper, the production of protons, deuterons and 3He^{3}\mathrm {He} and their charge conjugates at midrapidity is studied as a function of the charged-particle multiplicity in inelastic pp collisions at s=5.02\sqrt{s}=5.02 TeV using the ALICE detector. Within the uncertainties, the yields of nuclei in pp collisions at s=5.02\sqrt{s}=5.02 TeV are compatible with those in pp collisions at different energies and to those in p–Pb collisions when compared at similar multiplicities. The measurements are compared with the expectations of coalescence and Statistical Hadronisation Models. The results suggest a common formation mechanism behind the production of light nuclei in hadronic interactions and confirm that they do not depend on the collision energy but on the number of produced particles

    Advanced Virgo Plus: Future Perspectives

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    HAL CCSD
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    International audienceWhile completing the commissioning phase to prepare the Virgo interferometer for the next joint Observation Run (O4), the Virgo collaboration is also finalizing the design of the next upgrades to the detector to be employed in the following Observation Run (O5). The major upgrade will concern decreasing the thermal noise limit, which will imply using very large test masses and increased laser beam size. But this will not be the only upgrade to be implemented in the break between the O4 and O5 observation runs to increase the Virgo detector strain sensitivity. The paper will cover the challenges linked to this upgrade and implications on the detector’s reach and observational potential, reflecting the talk given at 12th Cosmic Ray International Seminar - CRIS 2022 held in September 2022 in Napoli

    Search for New Physics in Electronic Recoil Data from XENONnT

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    American Physical Society
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    International audienceWe report on a blind analysis of low-energy electronic-recoil data from the first science run of the XENONnT dark matter experiment. Novel subsystems and the increased 5.9 tonne liquid xenon target reduced the background in the (1, 30) keV search region to (16.1±1.3)(16.1 \pm 1.3) events/(tonne×\timesyear×\timeskeV), the lowest ever achieved in a dark matter detector and ∼\sim5 times lower than in XENON1T. With an exposure of 1.16 tonne-years, we observe no excess above background and set stringent new limits on solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter

    JRJC 2021- Journées de Rencontres Jeunes Chercheurs. Book of Proceedings

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    HAL CCSD
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    Journées de Rencontres Jeunes Chercheurs (JRJC2021). 17-23 octobre 2021, La Rochelle (France)International audienc

    Radiation exposure of microorganisms living in radioactive mineral springs

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    HAL CCSD
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    International audienc

    Nuclear modification factor of light neutral-meson spectra up to high transverse momentum in p–Pb collisions at sNN=8.16 TeV

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    HAL CCSD
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    International audienceNeutral pion (π0) and η meson production cross sections were measured up to unprecedentedly high transverse momenta (pT) in p–Pb collisions at sNN=8.16TeV. The mesons were reconstructed via their two-photon decay channel in the rapidity interval −1.3<y<0.3 in the ranges of 0.4<pT<200 GeV/c and 1.0<pT<50 GeV/c, respectively. The respective nuclear modification factor (RpPb) is presented for pT up to of 200 and 30 GeV/c, where the former was achieved by extending the π0 measurement in pp collisions at s=8TeV using the merged cluster technique. The values of RpPb are below unity for pT<10 GeV/c, while they are consistent with unity for pT>10 GeV/c, leaving essentially no room for final state energy loss. The new data provide strong constraints for nuclear parton distribution and fragmentation functions over a broad kinematic range and are compared to model predictions as well as previous results at sNN=5.02TeV

    An approximate likelihood for nuclear recoil searches with XENON1T data

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    HAL CCSD
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    International audienceThe XENON collaboration has published stringent limits on specific dark matter -nucleon recoil spectra from dark matter recoiling on the liquid xenon detector target. In this paper, we present an approximate likelihood for the XENON1T 1 tonne-year nuclear recoil search applicable to any nuclear recoil spectrum. Alongside this paper, we publish data and code to compute upper limits using the method we present. The approximate likelihood is constructed in bins of reconstructed energy, profiled along the signal expectation in each bin. This approach can be used to compute an approximate likelihood and therefore most statistical results for any nuclear recoil spectrum. Computing approximate results with this method is approximately three orders of magnitude faster than the likelihood used in the original publications of XENON1T, where limits were set for specific families of recoil spectra. Using this same method, we include toy Monte Carlo simulation-derived binwise likelihoods for the upcoming XENONnT experiment that can similarly be used to assess the sensitivity to arbitrary nuclear recoil signatures in its eventual 20 tonne-year exposure

    Contrôle en ligne du faisceau FLASH au cyclotron ARRONAX

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    HAL CCSD
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    Mesure de la production de J/ψ lors de collisions Pb-Pb à √s=5.02 TeV avec le spectromètre à muons de l'expérience ALICE-CERN

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    HAL CCSD
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    Ultra-relativistic heavy ion collisions aim at creating and studying, in the laboratory, the hadronic matter at high temperature and energy density.According to the QCD, a deconfined state of partonic matter, the Quark-Gluon Plasma (QGP), should be created at temperatures exceeding 200 MeV (about a trillion degrees).The production of charmonium states (J/ψ et ψ(2S)) is one of the various probes studied to access to the QGP properties. In the presence of a strongly interacting medium, its production rate is affected by different mechanisms varying with the energy of the collision. A suppression associated to the color screening of the quark-antiquark pair was already observed by many experiments at the SPS and RHIC. However, this suppression was found to be less significant at low transverse momentum for LHC energies that can be explained by the recombination mechanism of charms anti-charms pairs during the QGP expansion.Also, the ALICE Collaboration reported in 2015 the first measurement of an excess in the yield of J/ψ at very low transverse momentum in Pb-Pb collisions at √sNN=2.76 TeV. The coherent photoproduction was proposed as the potential, although unexpected, underlying mechanism in collisions dominated by hadronic interactions. In this thesis, the inclusive J/ψ production was measured in Pb-Pb collisions at √sNN=5.02 TeV with the muon spectrometer of the ALICE experiment. The measurement of its nuclear modification factor (RAA) has been extended to the full data set corresponding to an integrated luminosity of 750 μb-1 and allowing for a better accuracy in centrality. Finally, the coherent photoproduction cross section has been exctrated from a yield with a significance greater than 5σ in the 30-50%, 50-70% and 70-90% centrality ranges.Les collisions d’ions lourds ultra-relativistes sont un outil unique pour créer et étudier en laboratoire la matière hadronique à hautes températures et hautes densités d’énergie. D’après la QCD, un état déconfiné de la matière hadronique, le Plasma de Quarks et de Gluons (QGP), devrait être créé à des températures excédant les 200 MeV (de l'ordre du billion des degrés). La production des états de charmonia (J/ψ et ψ(2S)) est l’une des multiples sondes étudiées pour accéder aux propriétés du QGP. En présence d’un milieu dense interagissant fortement, son taux de production est affecté par différents mécanismes variant avec l’énergie de la collision. Une suppression associée à l’écrantage de couleur de la paire de quarks-antiquarks fut déjà observée par de nombreuses expériences au SPS et au RHIC. Cette suppression s’est néanmoins avérée moins significative à basse impulsion transverse pour les énergies du LHC cela s’expliquant par l’action d’un mécanisme de recombinaison des charmes anti-charmes durant l’expansion du QGP. De plus, la collaboration ALICE a reporté en 2015 une première mesure d’un excès de J/ψ résidant à très basse impulsion transverse lors de collisions Pb-Pb à √sNN=2.76 TeV. La photoproduction cohérente fut proposée comme mécanisme sous-jacent, bien qu’inattendu lors de collisions dominées par les interactions hadroniques. Dans cette thèse, la production inclusive de J/ψ fut mesurée avec les collisions Pb-Pb à √sNN=5.02 TeV à l’aide du spectromètre à muons de l’expérience ALICE. La mesure de son facteur de modification nucléaire (RAA) a été étendue à l’ensemble des données correspondante à une luminosité intégrée de 750 μb-1 et permettant une meilleure précision en centralité. Enfin, la section efficace de photoproduction cohérente a été extraite à partir d'un taux significativement supérieur à 5σ dans les collisions d'une centralité de 30-50%, 50-70% et 70-90%

    Measurement of inclusive charged-particle b-jet production in pp and p-Pb collisions at sNN \sqrt{s_{\mathrm{NN}}} = 5.02 TeV

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    Springer
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    International audienceA measurement of the inclusive b-jet production cross section is presented in pp and p-Pb collisions at sNN \sqrt{s_{\mathrm{NN}}} = 5.02 TeV, using data collected with the ALICE detector at the LHC. The jets were reconstructed in the central rapidity region |η| < 0.5 from charged particles using the anti-kT_{T} algorithm with resolution parameter R = 0.4. Identification of b jets exploits the long lifetime of b hadrons, using the properties of secondary vertices and impact parameter distributions. The pT_{T}-differential inclusive production cross section of b jets, as well as the corresponding inclusive b-jet fraction, are reported for pp and p-Pb collisions in the jet transverse momentum range 10 ≤ pT,chjet_{T,ch jet}≤ 100 GeV/c, together with the nuclear modification factor, RpPbb−jet {R}_{\mathrm{pPb}}^{\mathrm{b}-\mathrm{jet}} . The analysis thus extends the lower pT_{T} limit of b-jet measurements at the LHC. The nuclear modification factor is found to be consistent with unity, indicating that the production of b jets in p-Pb at sNN \sqrt{s_{\mathrm{NN}}} = 5.02 TeV is not affected by cold nuclear matter effects within the current precision. The measurements are well reproduced by POWHEG NLO pQCD calculations with PYTHIA fragmentation.[graphic not available: see fulltext

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