Contribution, Social networking, and the Request for Adminship process in Wikipedia

International audienceIn epistemic communities, people are said to be selected on their contribution in knowledge to the project (articles, codes, etc.). However, the socialization process is an important factor for inclusion, sustainability as a contributor, and promotion. Finally, what matters for being promoted? Being a good contributor? Being a good animator? Knowing the boss? We explore this question by looking at the election process for administrators in the English Wikipedia. We used the candidates' revisions and/or social attributes to construct a predictive model of promotion success, based on the candidates' past behavior and a random forest algorithm. Our model explains 78% of the results, which is better than the former models. It also helps to refine the explanation of the election process

Recherche de monopôles magnétiques avec le télescope à neutrinos ANTARES

The ANTARES neutrino telescope is located at 2500 meters depth, and is composed by an array of 900 photomultipliers installed for the detection of Cherenkov light emitted by neutrinoinduced muons, after having interacted with matter, and in order to reconstruct their directions. However, besides of being capable to detect high energy neutrinos, neutrino telescopes could mesure the through going of magnetic monopoles in the detector. In this work, were first presented the different methods used in order to calibrate the photomultipliers, which are the heart of a neutrino telescope. The possibility to detect magnetic monopoles with ANTARES was then discussed, and a first analysis optimised for the search for high velocity magnetic monopoles showed the great sensitivity offered by the telescope. Finally, a track reconstruction algorithm was modified, and a new analysis this time sensitive over a wider range of velocities was performed. After the application of the last analysis on the data taken in 2008 with the ANTARES telescope, new upper limits on the upward going magnetic monopole flux, of masses lower than 1014 GeV were obtained, and are the best experimental constraints on their flux for the velocity region β " [0.65, 0.995].Le télescope à neutrinos ANTARES est situé à 2500 mètres de profondeur, et est composé d'un réseau de 900 photomultiplicateurs installés pour la détection de la lumière Cherenkov émise par des muons, induits par l'interaction de neutrinos avec la matière, et dans le but de reconstruire leur direction. Cependant en outre d'être en mesure de détecter des neutrinos de hautes énergies, les télescope à neutrinos pourraient mesurer le passage de monopôles magnétiques dans le détecteur. Dans ce travail, ont été présentées tout d'abord les différentes méthodes d'étalonnage utilisées afin de caractériser les photomultiplicateurs, qui sont le cœur d'un télescope à neutrinos. La possibilité de détecter des monopôles magnétiques avec ANTARES a ensuite été abordée, puis une première analyse optimisée pour la recherche de monopôles de hautes vitesses a montré la grande sensibilité offerte par le télescope. Enfin, un algorithme de reconstruction de traces a été modifié, et une nouvelle analyse cette fois sensible sur une plus grande gamme de vitesse a été effectuée. Après l'application de la dernière analyse sur les données prises en 2008 par le télescope ANTARES, de nouvelles limites supérieures sur le flux de monopôles magnétiques ascendants de masse inférieure 'a 1014 GeV ont finalement été obtenues, et sont les meilleures contraintes expérimentales sur leur flux pour la région de vitesse β " [0.625, 0.995]

Performance of the BACCUS Transition Radiation Detector

International audienceThe Boron And Carbon Cosmic rays in the Upper Stratosphere (BACCUS) balloon-borne exper-iment flew for 30 days over Antarctica in December 2016. It is the successor of the CREAMballoon program in Antarctica which recorded a total cumulative exposure of 161 days. BAC-CUS is primarily aimed to measure cosmic-ray boron and carbon fluxes at the highest energiesreachable with a balloon or satellite experiment, in order to provide essential information for abetter understanding of cosmic-ray propagation in the Galaxy. The payload is made of multipleparticle physics detectors which measure the charge up to Z=26 and energy of incident particlesfrom a few hundred GeV to a few PeV. The newly designed Transition Radiation Detector (TRD)measures signals that are a function of the charge and Lorentz factor. In April 2016, BACCUSwas taken to CERN in its flight configuration to characterize its detectors’ response to beams ofelectrons and pions. The performance of the TRD using beam test data are reported in this paper

Performance of the ISS-CREAM Calorimeter

International audienceThe Cosmic Ray Energetics And Mass experiment for the International Space Station (ISS-CREAM) is scheduled for launch in 2017. It is designed to directly measure and identify theelemental composition of incident Galactic cosmic rays from a few hundred GeV to PeV energies.Such large energy range sensitivity is reached by using an electromagnetic sampling calorimeter(CAL) which measures the energy deposit of particle-induced showers. The CAL is composedof twenty layers of tungsten plates interleaved with scintillating fibers, and glued together usingepoxy-coated fiberglass to comply with space launch requirements. In August 2015, beam testmeasurements were performed at CERN to verify the performance of the CAL using layers ofepoxy-coated fiberglass placed between tungsten plates. The CAL response to electron and pionbeams and its performance are reported and compared with previous beam test configurations