494 research outputs found

    Tracking and Alignment in the CMS detector

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    This Report summarises the alignment strategy of the CMS detector. Track reconstruction in the silicon tracker and muon chambers is briefly described. We then present the different sources of alignment information, in particular alignment algorithms using reconstructed tracks

    High-statistics study of the low-energy cosmic-muons angular distribution - Results from MICRO

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    We present results from MICRO, a muon telescope with good angular resolution, which has collected more than 31·106 cosmic muons. Upper limits are given for the flux coming from point sources and for the periodic component from Cygnus X3

    Muon tracking underground

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    We present a new design of plastic streamer tubes, optimized to match the experimental requirements of large-area under-ground detectors, where muon identification is needed with good angular resolution

    Tracking and Alignment with the Silicon Strip Tracker at the CMS Magnet Test Cosmic Challenge

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    Data were collected with a custom-built sub-structure of the silicon strip tracker, both during the preparation of the Magnet Test Cosmic Challenge and during the challenge itself. These data were used to evaluate performance of track reconstruction and detector alignment algorithms, both with and without magnetic field. The track reconstruction algorithm is described in detail and its performance presented, in terms of its efficiency, resolution and consistency with the results from other sub-detectors. A study of detector alignment is shown, including the use tracker construction information. The effect of alignment on track quality is discussed

    Calorimetry Task Force Report

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    In this note we summarize the studies and recommendations of the calorimeter simulation task force (CaloTF). The CaloTF was established in February 2008 in order to understand and reconcile the discrepancies observed between the CMS calorimetry simulation and the test beam data recorded during 2004 and 2006. As the result of studies by the CaloTF a new version of Geant4 was developed and introduced in the CMS detector simulation leading to significanly better agreement with test beam data. Fast and flexible parameterizations describing showering in the calorimeter are introduced both in the Full Simulation (with a Gflash-like approach) and in the Fast Simulation. The CaloTF has developed a strategy to rapidly tune the CMS calorimeter simulation using the first LHC collision data when it becomes available. The improvements delivered by the CaloTF have been implemented in the software release CMSSW 2.1.0

    An inclusive search for free quarks at PEP

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    Abstract We report the results of a search for fractionally charged particles in e + e ‚ąí reactions at a center of mass energy of 29 GeV. We find no evidence for such particles and present upper limitts on R q = ŌÉ q q X/ŌÉ őľőľ for change 1 3 e and 2 3 e which range from 1 to 8 √ó 10 ‚ąí2 for mass up to 12 GeV/ c 2

    Tracker Operation and Performance at the Magnet Test and Cosmic Challenge

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    During summer 2006 a fraction of the CMS silicon strip tracker was operated in a comprehensive slice test called the Magnet Test and Cosmic Challenge (MTCC). At the MTCC, cosmic rays detected in the muon chambers were used to trigger the readout of all CMS sub-detectors in the general data acquisition system and in the presence of the 4 T magnetic field produced by the CMS superconducting solenoid. This document describes the operation of the Tracker hardware and software prior, during and after data taking. The performance of the detector as resulting from the MTCC data analysis is also presented

    Differential cross section measurements for the production of a W boson in association with jets in proton‚Äďproton collisions at ‚ąös = 7 TeV

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    Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript ‚ąí1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

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