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Anisotropic flow of identified hadrons in Xe-Xe collisions at = 5.44 TeV
No full textInternational audienceMeasurements of elliptic (v) and triangular (v) flow coefficients of π, K, p+, , and Λ+ obtained with the scalar product method in Xe-Xe collisions at = 5.44 TeV are presented. The results are obtained in the rapidity range |y| < 0.5 and reported as a function of transverse momentum, p, for several collision centrality classes. The flow coefficients exhibit a particle mass dependence for p< 3 GeV/c, while a grouping according to particle type (i.e., meson and baryon) is found at intermediate transverse momenta (3 < p< 8 GeV/c). The magnitude of the baryon v is larger than that of mesons up to p = 6 GeV/c. The centrality dependence of the shape evolution of the p-differential v is studied for the various hadron species. The v coefficients of π, K, and p+ are reproduced by MUSIC hydrodynamic calculations coupled to a hadronic cascade model (UrQMD) for p< 1 GeV/c. A comparison with v measurements in the corresponding centrality intervals in Pb-Pb collisions at = 5.02 TeV yields an enhanced v in central collisions and diminished value in semicentral collisions.[graphic not available: see fulltext
- and (anti-)-hadron correlations in pp collisions at TeV
No full textInternational audienceTwo-particle Azimuthal correlations are measured with the ALICE apparatus in pp collisions at TeV to explore strangeness- and multiplicity-related effects in the fragmentation of jets and the transition regime between bulk and hard production, probed with the condition that a strange meson () or baryon () with transverse momentum GeV/ is produced. Azimuthal correlations between kaons or hyperons with other hadrons are presented at midrapidity for a broad range of the trigger ( GeV/) and associated particle (1 GeV/), for minimum-bias events and as a function of the event multiplicity. The near- and away-side peak yields are compared for the case of either or () being the trigger particle with that of inclusive hadrons (a sample dominated by pions). In addition, the measurements are compared with predictions from PYTHIA 8 and EPOS LHC event generators
Vers la recherche d’un neutrino stérile avec l’expérience SoLid au réacteur BR2 de SCK- CEN : calibration du détecteur et conception d’une sélection topologique et multivariée d’événements antineutrinos
No full textThe SoLid experience is based near the BR2 research reactor at SCK-CEN, Belgium. Its aim is to search for neutrino oscillation at very short baseline, which would explain the so-called Reactor Antineutrino Anomaly via the presence of a new particle, a sterile neutrino. The measurement of antineutrino energy spectrum from the reactor highly enriched in Uranium 235, SoLid would help to understand the disagreement between predicted and measured observed by previous experiment (so-called 5 MeV bump). In order to fight against the important cosmic induced background inherent in ground-level experiment, the SoLid detector is high segmented: with 12,800 detection cells read-out by 3,200 MPPCs. Electronic antineutrinos are detected via Inverse Beta Decay (IBD), thanks to a new detection technology involving the combination of plastic scintillator, the PVT, and mineral scintillator, the ZNS. Thesis contributions could divided in three main parts. First consisted in the energy calibration of the detector. This is a challenge due to the high segmentation of the target. The second one extended the calibration by adjusting the energy response in the simulation improved its code. Finally, the last one conceived the selection and extraction of the signal. With the development of new discriminating variables which exploits the annihilation gammas from IBD and using multivariate analysis tools. Then via the improvement of the official signal extraction method and the development of a new one for comparison purpose. Among other things, my work allows to control the energy scale of SoLid cubes at around a 2% level and improve by a factor 4 the signal over back-ground ratio for the same signal efficiency.L’expérience SoLid est basée auprès du réacteur de recherche BR2 à SCK-CEN, Belgique. Son but est de rechercher une oscillation de neutrino à très courte distance, qui expliquerait l’anomalie dite du flux d’antineutrinos de réacteur, par la présence d’une nouvelle particule, le neutrino stérile. En mesurant le spectre en énergie des antineutrinos émis par ce réacteur très enrichi en Uranium 235, SoLid aiderait aussi à comprendre la différence de forme entre spectres prédit et mesuré, constatée par des expériences antérieures ("bump à 5MeV"). Afin de lutter contre les importants bruits de fond d’origine cosmique inhérents aux expériences situées en surface, SoLid a opté pour une segmentation très élevée : le détecteur se compose de 12,800 cellules de détection lues par 3,200 MPPC. Les antineutrinos électroniques sont détectés via des Décroissances Beta Inverses (IBD), avec une nouvelle technologie de détection s’appuyant sur l’association d’un scintillateur plastique (PVT) et minéral (ZnS). Les contributions de cette thèse peuvent se diviser en trois principales parties. Un premier volet a consisté dans la calibration en énergie du détecteur. Ceci est un défi au vu de la haute segmentation du détecteur. La seconde contribution a porté sur l’ajustement de la réponse en énergie dans la simulation et a amélioré son code. Enfin, la dernière contribution a porté sur la sélection et l’extraction du signal. Tout d’abord avec le développement de nouvelles variables discriminantes exploitant les gamma d’annihilations issus de l’IBD et en utilisant des techniques d’analyse multivariable. Puis via l’amélioration de la méthode officielle d’extraction du signal et le développement d’une nouvelle méthode à des fins de comparaison. Mes travaux permettent entre autres de maîtriser l’échelle en énergie des cubes de SoLid à environ 2% et d’améliorer d’un facteur 4 le rapport signal sur bruit de la sélection d’événements IBD, en maintenant constante son efficacité sur le signal
Radiocesium in Shiitake mushroom: Accumulation in living fruit bodies and leaching from dead fruit bodies
No full textInternational audienceIn this paper, cesium (Cs) accumulation by the saprophytic fungus Lentinula edodes (Shiitake) was investigated to contribute to the elucidation of radiocesium-cycling mechanisms in forest environments. Although the 137Cs in the mushroom bed before culture was bioavailable, the transfer factor (TF) of Cs (133Cs and 137Cs) from the mushroom bed to fruit bodies was low (approximately 1) and the TFs of K (5) and Na (1.5) were higher. Cs and K concentrations in fruit bodies at different maturity stages were almost constant. The concentration ratio of Cs/K is constant in the pileus regardless of the pileus tissues. These results demonstrate that Shiitake non-specifically accumulates Cs while accumulating the essential element K and provide evidence that no selective Cs accumulation (or binding) sites exist within the Shiitake fruit body. Furthermore, the present results show that most accumulated Cs quickly leaches out from the dead fruit body with exposure to water. The leached Cs was largely adsorbable on clay minerals, suggesting that the Shiitake fruit body likely contains Cs in the cation form
Impact of hadronisation process and hadronic cascades on the 2nd order susceptibilities studied with the EPOS event generator
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HEPiX Benchmarking Solution for WLCG Computing Resources
No full textInternational audienceThe HEPiX Benchmarking Working Group has developed a framework to benchmark the performance of a computational server using the software applications of the High Energy Physics (HEP) community. This framework consists of two main components, named HEP-Workloads and HEPscore. HEP-Workloads is a collection of standalone production applications provided by a number of HEP experiments. HEPscore is designed to run HEP-Workloads and provide an overall measurement that is representative of the computing power of a system. HEPscore is able to measure the performance of systems with different processor architectures and accelerators. The framework is completed by the HEP Benchmark Suite that simplifies the process of executing HEPscore and other benchmarks such as HEP-SPEC06, SPEC CPU 2017, and DB12. This paper describes the motivation, the design choices, and the results achieved by the HEPiX Benchmarking Working group. A perspective on future plans is also presented
