=========================================================== KEK@Detector Seminar Title: "Precise Calibration of the ATLAS liquid argon calorimeter in an electron test-beam at CERN" Speaker: Tancredi Carli (CERN) Date: 19 September 2007 (Wed) 11:00 -12:00 Place KEK 3 go-kan, room 425 Video Connection KEK MCU xxxxxx =========================================================== Abstract: One of the challenges to fully exploit the LHC physics program is the precise measurement of the electron and photon energy with the@electromagnetic calorimeter. Goals set by the ATLAS technical design report are a linearity of 0.1% and a uniformity of 0.4%. One of the ATLAS Liquid Argon calorimeter (Lar) barrel production modules has been exposed in the year 2002 to an electron test-beam at the H8 beam-line at CERN to investigate what precision can be reached in the clean test-beam environment. The available energies of the electron beam ranged from 10 to 245 GeV. A detailed study of several effects biasing the electron energy measurement allowed an energy reconstruction procedure to be developed that ensures a good linearity and a good resolution. It is demonstrated that only a calibration that is based on Monte Carlo simulation is able to reach the required precision. Special emphasis is put on dead material corrections and to the effect of sampling fraction variations along the shower axis. The systematic uncertainty of the measurement is about 0.1% per effect at low energies and negligible at high energies. The ability of the Geant4 simulation to describe@electromagnetic showers is also discussed. ===========================================================