2,181 research outputs found

    The CMS Pixel Detector: from production to commissioning

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    The CMS experiment at the LHC includes a hybrid silicon pixel detector for the reconstruction of charged tracks and of the interaction vertices. The detector is made of three barrel layers and two disks at each end of the barrel. Detector modules consist of thin, segmented silicon sensors with highly integrated readout chips connected by the bump bonding technique. In this paper we report on the progress of the detector construction and testing. In addition, first results from the commissioning systems at CERN and PSI are presented.Comment: 7 pages, 2 figures. Presented at the 10th ICATPP conference, Villa Olmo, Como (Italy), 8-12 October, 200

    Studies of exotic hadrons at Tevatron and LHC

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    In these proceedings we summarise the recent studies of exotic hadrons performed at the LHC and Tevatron. The X(3872) production cross section and mass measurements are reported, along with the determination of its quantum numbers, the searches for decays to ppˉ\mathrm{p\bar{p}}, and for partner states in the bottomonium sector. Furthermore, we discuss the Y(4140) and Y(4274) structures, observed by several experiments in the J/ψϕJ/\psi\phi invariant mass spectrum.Comment: Presented at the XV International Conference on Hadron Spectroscopy-Hadron 2013, 4-8 November 2013, Nara, Japan. 7 pages, 2 figure

    Sensor Simulation and position calibration for the CMS pixel detector

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    In this paper a detailed simulation of irradiated pixel sensors was used to investigate the effects of radiation damage on charge sharing and position determination. The simulation implements a model of radiation damage by including two defect levels with opposite charge states and trapping of charge carriers. We show that charge sharing functions extracted from the simulation can be parameterized as a function of the inter-pixel position and used to improve the position determination. For sensors irradiated to Phi=5.9x10^14 n/cm^2 a position resolution below 15 um can be achieved after calibration.Comment: Presented at the 14th Int. Workshop on Vertex Detectors (Vertex 2005), November 7-11 2005, Chuzenji Lake, Nikko, Japan. 4 pages, 1 figur

    Heavy flavor physics with the CMS experiment

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    Thanks to the excellent tracking and muon identification performance, combined with a flexible trigger system, the CMS experiment at the Large Hadron Collider is conducting a rich and competitive program of measurements in the field of heavy flavor physics. We review the status of b-quark production cross section measurements in inclusive and exclusive final states, the measurement of B hadron angular correlations, the search for rare Bs0B^0_s and B0B^0 decays to dimuons, and the observation of the X(3872) resonance.Comment: Presented at the 2011 Hadron Collider Physics symposium (HCP-2011), Paris, France, November 14-18 2011, 4 pages, 4 figure

    The ZEUS Micro Vertex Detector

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    During the HERA luminosity shutdown period 2000/01 the tracking system of the ZEUS experiment has been upgraded with a silicon Micro Vertex Detector (MVD). The barrel part of the detector consists of three layers of single sided silicon strip detectors, while the forward section is composed of four wheels. In this report we shortly present the assembly procedure and in more details the test beam results on the spatial resolution of half modules. The first results of a cosmic ray test are presented and the radiation monitor system is described.Comment: 8 pages, 5 figures, Talk presented at the VERTEX 2001 Workshop, 23-28 Sept. 2001, Brunnen, Switzerland. Submitted to Nucl. Instr. and Meth.

    Latest measurements of beauty quark production at HERA

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    The latest results of beauty quark production measurements at HERA are presented. New measurements have been obtained both in the photoproduction and the deep inelastic scattering regimes. The results were compared with the NLO QCD calculations.Comment: 3 pages, 2 figures. Talk presented at the 31st International Conference on High Energy Physics (ICHEP02), Amsterdam, The Netherlands, July 24-31, 200

    Lorentz angle calibration for the barrel pixel detector

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    A method to measure the Lorentz angle in the barrel pixel detector of CMS is presented. This measurement from CMS data will be necessary during operation since the electric field in the sensors will change with increasing irradiation. The approach described in this note uses well measured muon tracks to determine the drift of the electrons in the pixel sensors. From an analysis of simulated data an accuracy of 2% on tau_L can be achieved from just 1000 muon tracks. This corresponds to a systematic shift in the hit reconstruction of less than 1.5 \mu m which will decrease with increasing integrated luminosity

    Recent studies of top quark properties and decays at hadron colliders

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    The top quark is the heaviest known elementary particle. Observed for the first time in 1995 at the Tevatron by the CDF and D0 experiments, it has become object of several studies aimed at fully characterize its properties and decays. Precise determinations of top quark characteristics verify the internal consistency of the standard model and are sensitive to new physics phenomena. With the advent of the large top quark production rates generated at the LHC, top quark studies have reached unprecedented statistical precision. This review summarizes the recent measurements of top quark properties and studies of its decays performed at the LHC and Tevatron.Comment: 13 pages, 4 figures, 5 tables, Presented at Flavor Physics and CP Violation (FPCP 2012), Hefei, China, May 21-25, 201

    Dijet azimuthal decorrelations in pp collisions at √s=7  TeV

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    Measurements of dijet azimuthal decorrelations in pp collisions at √s=7  TeV using the CMS detector at the CERN LHC are presented. The analysis is based on an inclusive dijet event sample corresponding to an integrated luminosity of 2.9  pb-1. The results are compared to predictions from perturbative QCD calculations and various Monte Carlo event generators. The dijet azimuthal distributions are found to be sensitive to initial-state gluon radiation. Published by American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. © 2011 CERN, for the CMS Collaboratio
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