513 research outputs found

    Analysing the Control Software of the Compact Muon Solenoid Experiment at the Large Hadron Collider

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    The control software of the CERN Compact Muon Solenoid experiment contains over 30,000 finite state machines. These state machines are organised hierarchically: commands are sent down the hierarchy and state changes are sent upwards. The sheer size of the system makes it virtually impossible to fully understand the details of its behaviour at the macro level. This is fuelled by unclarities that already exist at the micro level. We have solved the latter problem by formally describing the finite state machines in the mCRL2 process algebra. The translation has been implemented using the ASF+SDF meta-environment, and its correctness was assessed by means of simulations and visualisations of individual finite state machines and through formal verification of subsystems of the control software. Based on the formalised semantics of the finite state machines, we have developed dedicated tooling for checking properties that can be verified on finite state machines in isolation.Comment: To appear in FSEN'11. Extended version with details of the ASF+SDF translation of SML into mCRL

    Commissioning and early physics analysis with the ATLAS and CMS experiments

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    These lecture notes for graduate students and young postdocs introduce the commissioning and early physics programme of the high-transverse-momentum experiments ATLAS and CMS, operating at the Large Hadron Collider (LHC) at CERN.Comment: Lecture notes from the 5th Latin American School of High-Energy Physics, Recinto Quirama, Colombia, March 15-28, 2009; 84 pages, 92 Figure

    Generating and Solving Symbolic Parity Games

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    We present a new tool for verification of modal mu-calculus formulae for process specifications, based on symbolic parity games. It enhances an existing method, that first encodes the problem to a Parameterised Boolean Equation System (PBES) and then instantiates the PBES to a parity game. We improved the translation from specification to PBES to preserve the structure of the specification in the PBES, we extended LTSmin to instantiate PBESs to symbolic parity games, and implemented the recursive parity game solving algorithm by Zielonka for symbolic parity games. We use Multi-valued Decision Diagrams (MDDs) to represent sets and relations, thus enabling the tools to deal with very large systems. The transition relation is partitioned based on the structure of the specification, which allows for efficient manipulation of the MDDs. We performed two case studies on modular specifications, that demonstrate that the new method has better time and memory performance than existing PBES based tools and can be faster (but slightly less memory efficient) than the symbolic model checker NuSMV.Comment: In Proceedings GRAPHITE 2014, arXiv:1407.767

    Mechanical Design of the HGCal Wedges with Thermal Gradient

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    After the discovery of the Higgs Boson, the purpose of the world's largest and most powerful particle accelerator, the Large Hadron Collider (LHC), seemed to have been achieved. Despite the fact that the Standard Model apparently complies with most experimental data up to this day, the majority of particle physicists feel that it is not a complete framework [1]. Therefore, there are still many unresolved problems in the physics of elementary particles. That is the reason why, in 2013, the European Strategy for Particle Physics announced its update. The High-Luminosity Large Hadron Collider (HL-LHC) project aims to increase luminosity by a factor of 10 beyond the LHC’s design. The higher the luminosity, the more data the experiments can gather to allow scientists to observe rare processes. Its development depends on several technological innovations, like the High-Granularity Calorimeter (HGCal), a major upgrade of the Compact Muon Solenoid (CMS) detector. [2] This project analyses the design and optimisation processes of the supports (wedges) which join the calorimeter (HGCal) to the related parts of the CMS detector. Specifically, the study focuses on the intermediate wedges. The main challenge is to create an optimal configuration for both the operational (vertical) and the assembly (horizontal) position. For this reason, a series of mechanical, magnetic and thermal considerations must be taken into account. This includes withstanding a mass of 200 tons and 50 °� of thermal difference. In order to achieve this goal, it is first necessary to analyse the functionality of the detector. This in-depth research allows a precise problem definition. Later, the preliminary design of the intermediate wedges is studied. By analysing the finite element results, the optimisation steps are established. At the end, the final version, the results of its analyses and some suggestions for the building process are presented. In the final result analyses, a hybrid configuration of fixed and hinged intermediate wedges was presented. In the operational position, stresses and vertical load values were lowered. In addition, a thermal analysis concluded that the heat transfer was sufficient for meeting the given requirements. In the assembly analysis, it was verified that the supports are not buckling or permanently deforming

    The International Linear Collider Technical Design Report - Volume 4: Detectors

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    The International Linear Collider Technical Design Report (TDR) describes in four volumes the physics case and the design of a 500 GeV centre-of-mass energy linear electron-positron collider based on superconducting radio-frequency technology using Niobium cavities as the accelerating structures. The accelerator can be extended to 1 TeV and also run as a Higgs factory at around 250 GeV and on the Z0 pole. A comprehensive value estimate of the accelerator is give, together with associated uncertainties. It is shown that no significant technical issues remain to be solved. Once a site is selected and the necessary site-dependent engineering is carried out, construction can begin immediately. The TDR also gives baseline documentation for two high-performance detectors that can share the ILC luminosity by being moved into and out of the beam line in a "push-pull" configuration. These detectors, ILD and SiD, are described in detail. They form the basis for a world-class experimental programme that promises to increase significantly our understanding of the fundamental processes that govern the evolution of the Universe.Comment: See also http://www.linearcollider.org/ILC/TDR . The full list of signatories is inside the Repor

    A CMS kísérlet Barrel Müon Helyzetmeghatározó Rendszerének kalibrációja, validációja és működtetése

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    A doktori disszertáció célja a CERN (Európai Nukleáris Kutatási Szervezet, Conseil Européen pour la Recherche Nucléaire) intézet Nagy Hadron Ütköztető (LHC, Large Hadron Collider) gyorsítójánál működő Kompakt Müon Szolenoid (CMS, Compact Muon Solenoid) kísérlet Barrel Muon Spektrométer pozíció meghatározó rendszerének építésevel, validációjával és üzemeltetésével kapcsolatban végezett munkám ismertetése.The aim of the PhD thesis is to describe my work on the construction, installation, validation and operation of the position monitoring (called also alignment) system of the Barrel Muon Spectrometer of the CMS (Compact Muon Solenoid) experiment located in the P5 experimental hall of the Large Hadron Collider (LHC) accelerator at CERN (Conseil Européen pour la Recherche Nucléaire
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