M. Karam Ouharou

A u terme d'une dizaine d'années de R&D, l'Irfu a livré au Cern, en juillet 2021, 74 nouvelles cartes électroniques destinées au calorimètre électromagnétique d'Atlas, produites par la société FEDD. Ces cartes supporteront le flux de données croissant qui sera produit par le LHC dès son redémarrage, en février 2022. Les calorimètres électromagnétique et hadronique de l'expérience Atlas jouent un rôle essentiel dans l'identification des produits de collisions proton-proton du LHC parmi d'innombrables combinaisons. Segmentées en couches concentriques, les cellules des calorimètres mesurent sélectivement les dépôts d' énergie électromagnétique (électrons ou photons) et hadronique plus pénétrants (protons, pions, jets reliés à des quarks, gluons de basse énergie , etc). Dans ce contexte , le système de déclenchement du calorimètre électromagnétique doit opérer un tri extrêmement rapide pour ne prendre en compte que les données des région...

Einstein’s equation To start we give an exposition of elementary topics in the geometry of space, and the spatial tensorial character of physical laws in prerelativity physics. We formulate general relativity and provide a motivation for Einstein’s equation, which relates the geometry of spacetime to the distribution of matter in the universe. 1.2.1 General and Special Covariance Assume that space has the manifold structure of R 3 and the association of points of space with elements (x 1 , x2 , x3 ) of R 3 can be accomplished by construction of a rigid rectilinear grid of metersticks. We call the coordinates of space derived in this manner as Cartesian coordinates [24]. The distance, S, between two points, x and ¯x, defined in terms of Cartesian coordinates by S 2 = (x 1 − x¯ 1 ) 2 + (x 2 − x¯ 2 ) 2 + (x 3 − x¯ 3 ) 2 (1.1) This formula is the distance between two points. Referred to equation (1.1), the distance between two nearby points is (δS) 2 = (δx1 ) 2 + (δx2 ) 2 + (δx3 ) 2 (1.2) ...

  Extraction of Energy from a Black Hole KARAM OUHAROU December 8, 2016 Submitted as coursework for PH220, Fall 2016 Introduction If the current understanding of astrophysics and relativity is correct, rotating black holes as systems exist within the universe. These systems are formed when a star can no longer support itself against its own gravitational collapse, thereby compressing to a point where normal space-time breaks down and, since stars are rotating in space, in order to preserve conservation of momentum, the black hole itself must have a non-zero rotational angular momentum. In theory, once anything, including energy, passes the event horizon, it cannot return, but, according to Roger Blandford, Roman Znajek, and Roger Penrose, energy can be extracted from the black hole itself. If humanity ever does explore the galaxy, provided that a black hole can be found, it may become a viable power source, but for now, it is an interesting theoretical system that ...