Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 31Citation - Scopus: 32Alignment of the Cms Tracker With Lhc and Cosmic Ray Data(IOP Publishing Ltd., 2014) Karapınar, Güler; Demir, Durmuş AliThe central component of the CMS detector is the largest silicon tracker ever built. The precise alignment of this complex device is a formidable challenge, and only achievable with a significant extension of the technologies routinely used for tracking detectors in the past. This article describes the full-scale alignment procedure as it is used during LHC operations. Among the specific features of the method are the simultaneous determination of up to 200 000 alignment parameters with tracks, the measurement of individual sensor curvature parameters, the control of systematic misalignment effects, and the implementation of the whole procedure in a multiprocessor environment for high execution speed. Overall, the achieved statistical accuracy on the module alignment is found to be significantly better than 10 mu m.Article Citation - WoS: 456Citation - Scopus: 423Description and Performance of Track and Primary-Vertex Reconstruction With the Cms Tracker(IOP Publishing Ltd., 2014) Demir, Durmuş Ali; CMS CollaborationA description is provided of the software algorithms developed for the CMS tracker both for reconstructing charged-particle trajectories in proton-proton interactions and for using the resulting tracks to estimate the positions of the LHC luminous region and individual primary-interaction vertices. Despite the very hostile environment at the LHC, the performance obtained with these algorithms is found to be excellent. For t (t) over bar events under typical 2011 pileup conditions, the average track-reconstruction efficiency for promptly-produced charged particles with transverse momenta of p(T) > 0.9GeV is 94% for pseudorapidities of vertical bar eta vertical bar < 0.9 and 85% for 0.9 < vertical bar eta vertical bar < 2.5. The inefficiency is caused mainly by hadrons that undergo nuclear interactions in the tracker material. For isolated muons, the corresponding efficiencies are essentially 100%. For isolated muons of p(T) = 100GeV emitted at vertical bar eta vertical bar < 1.4, the resolutions are approximately 2.8% in p(T), and respectively, 10 m m and 30 mu m in the transverse and longitudinal impact parameters. The position resolution achieved for reconstructed primary vertices that correspond to interesting pp collisions is 10-12 mu m in each of the three spatial dimensions. The tracking and vertexing software is fast and flexible, and easily adaptable to other functions, such as fast tracking for the trigger, or dedicated tracking for electrons that takes into account bremsstrahlung.Article Citation - WoS: 105Citation - Scopus: 79Performance of the Cms Missing Transverse Momentum Reconstruction in Pp Data at Root S=8 Tev(IOP Publishing Ltd., 2015) Demir, Durmuş Ali; CMS CollaborationThe performance of missing transverse energy reconstruction algorithms is presented using root s = 8 TeV proton-proton (pp) data collected with the CMS detector. Events with anomalous missing transverse energy are studied, and the performance of algorithms used to identify and remove these events is presented. The scale and resolution for missing transverse energy, including the effects of multiple pp interactions (pileup), are measured using events with an identified Z boson or isolated photon, and are found to be well described by the simulation. Novel missing transverse energy reconstruction algorithms developed specifically to mitigate the effects of large numbers of pileup interactions on the missing transverse energy resolution are presented. These algorithms significantly reduce the dependence of the missing transverse energy resolution on pileup interactions. Finally, an algorithm that provides an estimate of the significance of the missing transverse energy is presented, which is used to estimate the compatibility of the reconstructed missing transverse energy with a zero nominal value.Article Citation - WoS: 111Citation - Scopus: 97Missing Transverse Energy Performance of the Cms Detector(IOP Publishing Ltd., 2011) Karapınar, Güler; Demir, Durmuş AliDuring 2010 the LHC delivered pp collisions with a centre-of-mass energy of 7 TeV. In this paper, the results of comprehensive studies of missing transverse energy as measured by the CMS detector are presented. The results cover the measurements of the scale and resolution for missing transverse energy, and the effects of multiple pp interactions within the same bunch crossings on the scale and resolution. Anomalous measurements of missing transverse energy are studied, and algorithms for their identification are described. The performance of several reconstruction algorithms for calculating missing transverse energy are compared. An algorithm, called missing-transverse-energy significance, which estimates the compatibility of the reconstructed missing transverse energy with zero, is described, and its performance is demonstrated. © 2011 CERN for the benefit of the CMS collaboration, published under license by IOP Publishing Ltd. SISSA.Article Citation - WoS: 519Citation - Scopus: 401Determination of Jet Energy Calibration and Transverse Momentum Resolution in Cms(IOP Publishing Ltd., 2011) Karapınar, Güler; Demir, Durmuş AliMeasurements of the jet energy calibration and transverse momentum resolution in CMS are presented, performed with a data sample collected in proton-proton collisions at a centre-of-mass energy of 7TeV, corresponding to an integrated luminosity of 36pb-1. The transverse momentum balance in dijet and γ/Z+jets events is used to measure the jet energy response in the CMS detector, as well as the transverse momentum resolution. The results are presented for three different methods to reconstruct jets: a calorimeter-based approach, the "Jet-Plus-Track" approach, which improves the measurement of calorimeter jets by exploiting the associated tracks, and the "Particle Flow" approach, which attempts to reconstruct individually each particle in the event, prior to the jet clustering, based on information from all relevant subdetectors.Article Citation - WoS: 113Citation - Scopus: 92Performance of ?-Lepton Reconstruction and Identification in Cms(IOP Publishing Ltd., 2012) Demir, Durmuş Ali; Karapınar, GülerThe performance of τ-lepton reconstruction and identification algorithms is studied using a data sample of proton-proton collisions at s = 7 TeV, corresponding to an integrated luminosity of 36 pb-1 collected with the CMS detector at the LHC. The τ leptons that decay into one or three charged hadrons, zero or more short-lived neutral hadrons, and a neutrino are identified using final-state particles reconstructed in the CMS tracker and electromagnetic calorimeter. The reconstruction efficiency of the algorithms is measured using τ leptons produced in Z-boson decays. The τ-lepton misidentification rates for jets and electrons are determined. © 2012 CERN for the benefit of the CMS collaboration, published under license by IOP Publishing Ltd and SISSA.Article Citation - WoS: 44Citation - Scopus: 88Performance and Operation of the Cms Electromagnetic Calorimeter(IOP Publishing Ltd., 2010) Demir, Durmuş Ali; Karapınar, GülerThe operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75 848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented. © 2010 IOP Publishing Ltd and SISSA.Article Citation - WoS: 34Citation - Scopus: 42Performance of Cms Hadron Calorimeter Timing and Synchronization Using Test Beam, Cosmic Ray, and Lhc Beam Data(IOP Publishing Ltd., 2010) Demir, Durmuş Ali; Karapınar, GülerThis paper discusses the design and performance of the time measurement technique and of the synchronization systems of the CMS hadron calorimeter. Time measurement performance results are presented from test beam data taken in the years 2004 and 2006. For hadronic showers of energy greater than 100 GeV, the timing resolution is measured to be about 1.2 ns. Time synchronization and out-of-time background rejection results are presented from the Cosmic Run At Four Tesla and LHC beam runs taken in the Autumn of 2008. The inter-channel synchronization is measured to be within 2 ns. © 2010 IOP Publishing Ltd and SISSA.Article Citation - WoS: 33Citation - Scopus: 44CMS Data Processing Workflows During an Extended Cosmic Ray Run(IOP Publishing Ltd., 2010) Demir, Durmuş Ali; Karapınar, GülerThe CMS Collaboration conducted a month-long data taking exercise, the Cosmic Run At Four Tesla, during October-November 2008, with the goal of commissioning the experiment for extended operation. With all installed detector systems participating, CMS recorded 270 million cosmic ray events with the solenoid at a magnetic field strength of 3.8 T. This paper describes the data flow from the detector through the various online and offline computing systems, as well as the workflows used for recording the data, for aligning and calibrating the detector, and for analysis of the data. © 2010 IOP Publishing Ltd and SISSA.Article Citation - WoS: 33Citation - Scopus: 44Aligning the Cms Muon Chambers With the Muon Alignment System During an Extended Cosmic Ray Run(IOP Publishing Ltd., 2010) Demir, Durmuş Ali; Karapınar, GülerThe alignment system for the muon spectrometer of the CMS detector comprises three independent subsystems of optical and analog position sensors. It aligns muon chambers with respect to each other and to the central silicon tracker. System commissioning at full magnetic field began in 2008 during an extended cosmic ray run. The system succeeded in tracking muon detector movements of up to 18 mm and rotations of several milliradians under magnetic forces. Depending on coordinate and subsystem, the system achieved chamber alignment precisions of 140-350 μm and 30-200 μrad, close to the precision requirements of the experiment. Systematic errors on absolute positions are estimated to be 340-590 μm based on comparisons with independent photogrammetry measurements. © 2010 IOP Publishing Ltd and SISSA.
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