Energy calibration and resolution of the CMS electromagnetic calorimeter in pp collisions at √s = 7 TeV

Journal article

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.

Authors: Chatrchyan, S; Khachatryan, V; Sirunyan, A; Tumasyan, A; Adam, W

• Journal: Journal of Instrumentation
• Volume: 8
• Issue: 9
• Pages: P09009-P09009
• Publication date: 2013-09-01
• DOI: 10.1088/1748-0221/8/09/P09009
• EISSN: 1748-0221
• Language: English
• Keywords: Gamma detectors (scintillators, CZT, HPG, HgI etc); Large detector systems for particle and astroparticle physics; Calorimeters