Results 1 - 10 of 1135
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[en] The aim of this work is to estimate the shower leakage from the CMS Endcap Hadron calorimeter (HE) due to electromagnetic secondaries and punch-through in the region of the ME1/1 Forward Muon Station. Two configurations are considered: with and without the CMS Endcap Electromagnetic calorimeter (EE). The experimental data have been taken during the combined beam test of CMS subdetectors (HE, ME, RPC, DT) at the CERN H2 beam facility in 2004. Serial CSC chambers (ready for installation in CMS) fully equipped with readout electronics have been exposed. Simulation of a beam test setup has been performed using the GEANT4-based simulation software package OSCAR.
[en] The configuration and composition of the CMS muon system are presented. The paper is focused on cathode strip chambers (CSC) used as the endcap muon system detectors. The goals and objectives of the endcap muon system upgrade are formulated. The main results of works accomplished for the ME1/1 CSCs upgrade and the new ME4/2 muon station construction during the LHC Long Shutdown-1 (2013–2014) are presented. The improved performances of the endcap muon system are shown using experimental data obtained after the upgrade (Run2 data).
[en] The rare decays B"0_s → μ"+μ"− and B"0 → μ"+μ"− are among the most promising investigation channels for the search of new physics. Their tiny branching fractions and their small theoretical relative uncertainties make these decays very sensitive to many new physics scenarios. I present the first successful reconstruction of the rare decay B"0_s → μ"+μ"−, the measurement of its branching fraction, and the most recent upper limit for the branching fraction of the B"0 → μ"+μ"− decay at CMS, performed with all data acquired at the LHC Run I.
[en] The CMS experiment features a pixel detector with three barrel layers and two discs per side, corresponding to an active silicon area of 1 m2. The detector delivered high-quality data during LHC Run 1. However, the CMS pixel detector was designed for the nominal instantaneous LHC luminosity of . It is expected that the instantaneous luminosity will increase and reach twice the design value before Long Shutdown 3, scheduled for 2023. Under such conditions, the present readout chip would suffer from data loss due to buffer overflow, leading to significant inefficiencies of up to 16%. The CMS collaboration is presently constructing a new pixel detector to replace the present device during the winter shutdown 2016/2017. The design of this new detector will be outlined, the construction status summarized and the performance described.
[en] The ME1/1 cathode strip chambers are the part of the CMS endcap muon system. They were designed and produced in Dubna. The chambers have been installed in the detector and commissioning has been completed. This paper describes chamber readout electronics and presents the results of the tests with cosmicray muons.
[en] We present the survey of the main tasks in upgrading the hadron endcap (HE) calorimeters of the CMS experiment at LHC. The results of the HE upgrade during the LHC Long Shutdown (2013–2014) and plans for upgrade during LHC Extended Year End Technical Stop (December 2016–May 2017) are discussed.
[en] Recent top quark properties measurements made with the CMS detector at the LHC are presented. The measurements summarized include spin correlation of top quark pairs, asymmetries, top quark mass, and the underlying event in top quark pair events. The results are compared to the standard model predictions and new physics models.
[en] CMS Cathode Strip Chambers (CSC) are used for muon identification, measurements, and trigger in the forward direction. The system comprises 540 six-layer detectors with the overall sensitive area of about 6000 m2 and has more than 500K electronics readout channels. Automated CSC Data Quality Monitoring system (CSC DQM) is an integral part of CSC commissioning and operation, as well as of the central CMS monitoring system. The system monitors CSC data format integrity, hardware-set diagnostic bits, and a large number of occupancy distributions (>100K histograms). It is designed to detect problems ranging from dead/intermittent or noisy channels/boards, readout timing discrepancies to inconsistencies in higher level reconstructed physics objects, and to propagate automatically corresponding alarms, with a properly assigned level of severity and a possible troubleshooting diagnostic, to the top level. Given a significant number of monitor-able objects, the system implementation specifically focuses on reducing complexity of monitoring and problems detection procedures for an end-user. The DQM system functions in various modes: local CSC system running, global CMS running, and offline (i.e. using already recorded data). In this contribution an overview of implementation, general performance, and operational experience are provided.
[en] This note presents the search for new physics in events with an electron or muon and missing transverse energy, using 2.2 fb"−"1 of pp collision data at a center-of-mass energy of 13TeV, collected with the CMS detector during 2015. The focus is set on the potential production of aW"′boson, as described by the Sequential Standard Model. No evidence of an excess relative to the standard model expectation is observed and upper limits at 95% confidence level are set on the production cross section times branching fractions of the W"′boson, which are translated into lower limits for the new boson mass. Masses below 4.4TeV are excluded when both the electron and muon final decay channels are combined together. These results significantly extend previously published limits.