27 research outputs found
Composite mirror facets for ground based gamma ray astronomy
No full textComposite mirrors for gamma-ray astronomy have been developed to fulfill the specifications required for the next generation of Cherenkov telescopes represented by CTA (Cherenkov Telescope Array). In addition to the basic requirements on focus and reflection efficiency, the mirrors have to be stiff, lightweight, durable and cost efficient. In this paper, the technology developed to produce such mirrors is described, as well as some tests that have been performed to validate them. It is shown that these mirrors comply with the needs of CTA, making them good candidates for use on a significant part of the array.Fil: Brun, Pierre. Commissariat A Energie Atomique; FranciaFil: Carton, P.-H. Commissariat A Energie Atomique; FranciaFil: Durand, D. Commissariat A Energie Atomique; FranciaFil: Glicenstein, J-F.. Commissariat A Energie Atomique; FranciaFil: Jeanney, C.. Commissariat A Energie Atomique; FranciaFil: Medina, Maria Clementina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto Argentino de Radioastronomia (i); ArgentinaFil: Micolon, P.. Commissariat A Energie Atomique; FranciaFil: Peyaud, B.. Commissariat A Energie Atomique; Franci
Les Mémoires d’Antoinette Micolon, Ursuline auvergnate : une triple marginalité
No full textcolloque de Tours, 1er juin 2012, « Les Minores des Mémoires de l’Ancien Régime : territoire oublié », à paraître aux éditions Minerve, dir. M.P. Pilorge, en 2014International audienceno abstrac
Status of the technologies for the production of the Cherenkov Telescope Array (CTA) mirrors
No full textThe Cherenkov Telescope Array (CTA) is the next generation very high-energy gamma-ray observatory, with at least 10 times higher sensitivity than current instruments. CTA will comprise several tens of Imaging Atmospheric Cherenkov Telescopes (IACTs) operated in array-mode and divided into three size classes: large, medium and small telescopes. The total reflective surface could be up to 10,000 m2 requiring unprecedented technological efforts. The properties of the reflector directly influence the telescope performance and thus constitute a fundamental ingredient to improve and maintain the sensitivity. The R&D status of lightweight, reliable and cost-effective mirror facets for the CTA telescope reflectors for the different classes of telescopes is reviewed in this paper
Etude de la faisabilite d'une camera a scintillation utilisant des barreaux fluorescents
No full textCNRS-CDST / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc
Fire and light in the western triduum: their use at tenebrae and at the paschal vigil
No full textThe stage-by-stage development of Tenebrae is described showing the extension of light-loss at Lauds on Good Friday to the three night offices of the Western Triduum. The emergence, development, and use of the hearse at Tenebrae from the eleventh century onwards is explored, together with the integration of that device into the liturgical drama that the service of Tenebrae represented. The varying number of lights used and the extinction-points are shown to be derived from differing liturgical traditions. The presence of other lights at the service is discussed; and the extinguishing of lights is shown to have a rememorative, not a utilitarian origin. The new fire ceremonies of all the Western rites, which were of Galilean origin, were deliberately adopted by the Church as part of her missionary work. An in-depth survey of the ritual surrounding the kindling of the fire and the subsequent procession with the fire into church reveals a heritage of different cultural and liturgical traditions. Not only was the threefold production of fire linked to the triple performance of Tenebrae;the new fire ceremony was integrated into the Paschal vigil liturgy because of the common theme of light; and to the former was extended the Passover motif. Not only are the geographical and liturgical origins of the Easter candle considered; an historical analysis is presented of both the Candle itself and of the ceremonial surrounding the blessing of the Candle. This ceremonial, being largely of Galilean provenance, is ex-aunined in relation to the corresponding Milanese, Mozarabic, and Roman Vigil liturgies, all of which are related to the Lucernariua of Jerusalem. The study shows that the late medieval Paschal ceremony of light was a synthesis of Roman and Galilean elements; and that a two fold tradition existed relating to the provision of light at the Vigil
