Energy calibration and resolution of the CMS electromagnetic calorimeter in pp collisions at √s = 7 TeV
Journal of Instrumentation, vol.8, no.9, 2013 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 8 Issue: 9
- Publication Date: 2013
- Doi Number: 10.1088/1748-0221/8/09/p09009
- Journal Name: Journal of Instrumentation
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Keywords: Calorimeters, Gamma detectors (scintillators, CZT, HPG, HgI etc), Large detector systems for particle and astroparticle physics
- Yıldız Technical University Affiliated: Yes
Abstract
The energy calibration and resolution of the electromagnetic calorimeter (ECAL) of the CMS detector have been determined using proton-proton collision data from LHC operation in 2010 and 2011 at a centre-of-mass energy of √s = 7 TeV with integrated luminosities of about 5fb-1. Crucial aspects of detector operation, such as the environmental stability, alignment, and synchronization, are presented. The in-situ calibration procedures are discussed in detail and include the maintenance of the calibration in the challenging radiation environment inside the CMS detector. The energy resolution for electrons from Z-boson decays is better than 2% in the central region of the ECAL barrel (for pseudorapidity |η| < 0.8) and is 2-5% elsewhere. The derived energy resolution for photons from 125 GeV Higgs boson decays varies across the barrel from 1.1% to 2.6% and from 2.2% to 5% in the endcaps. The calibration of the absolute energy is determined from Ze→+e - decays to a precision of 0.4% in the barrel and 0.8% in the endcaps. © 2013 CERN for the benefit of the CMS collaboration.