ATLAS Hadronic Calorimeter Calibration Workshop MPI Munich May

ATLAS Hadronic Calorimeter Calibration Workshop MPI, Munich, May 3 -5, 2006 May 3, 2006 Electromagnetic Energy Scale in the FCal 1 Peter Loch University of Arizona Tucson, Arizona 85721 Electromagnetic Energy Scale in the FCal Peter Loch University of Arizona

ATLAS Hadronic Calorimeter Calibration Workshop MPI, Munich, May 3 -5, 2006 May 3, 2006 Electromagnetic Energy Scale in the FCal 2 Peter Loch University of Arizona Tucson, Arizona 85721 Reminder: the FCal is a bit special*… relaxed precision requirements (“few percent”) compared to other calorimeters; calibration pulse injected directly at pre-amp input -> very different signal path wrt physics signal, not usable for continuity check… …but signal reflections are usable to detect discontinuities and other problems along physics signal path -> optimized calibration pulse shape for this purpose, not for precision calibration (no usable calibration ramp)! Therefore, scale from testbeam, readout modeling and shower simulations alone exercised quite extensively with 1998 testbeam data for FCal 1 Module 0 and, to lesser extend, with FCal 2 Module 0 (track & hold readout only, ADC conversion factors not applicable to ATLAS-like read-out) -> two internal notes, NIM this spring (!!); presently under study: 2003 FCal testbeam data (FCal 1 scale alone) -> big problem with delay in simulations (it’s coming together very slowly!) *see J. Rutherfoord’s transparencies attached to the agenda!

Electromagnetic Energy Scale in the FCal 3 Peter Loch University of Arizona Tucson, Arizona 85721 relative difference MC-Data (%) ATLAS Hadronic Calorimeter Calibration Workshop MPI, Munich, May 3 -5, 2006 May 3, 2006 Electron signal features in FCal 1 in 1998 testbeam (1): 80 Ge. V e+ FCal 1 noise cut level (σnoise) Experimental (“real life”) electronic noise is added to Geant 3/Geant 4 simulations cell by overlaying simulated event with randomly triggered empty experimental events -> constraints experimental scale!

ATLAS Hadronic Calorimeter Calibration Workshop MPI, Munich, May 3 -5, 2006 May 3, 2006 Electromagnetic Energy Scale in the FCal 4 Peter Loch University of Arizona Tucson, Arizona 85721 Electron signal features in FCal 1 in 1998 testbeam (2): not all electromagnetic shower features well described: in Geant 4 constant term of relative energy resolution too large (left); more often signals with higher significance in experiment than in both simulations (right) – but careful: 1998 analysis with Geant 4. 2. 0! Also right plot sensitive to very precise modeling of beam profile/impact point in FCal…

ATLAS Hadronic Calorimeter Calibration Workshop MPI, Munich, May 3 -5, 2006 May 3, 2006 Electromagnetic Energy Scale in the FCal Peter Loch University of Arizona Tucson, Arizona 85721 5 Electron signal features in FCal 2 in 1998 testbeam: P. Estabrooks/G. Oakham/P. Krieger

ATLAS Hadronic Calorimeter Calibration Workshop MPI, Munich, May 3 -5, 2006 May 3, 2006 Electromagnetic Energy Scale in the FCal 6 Peter Loch University of Arizona Tucson, Arizona 85721 Activities and plans: 2003 analysis still fighting with electronic signal features, beam particle definitions, run selections, etc. ; but software and (most) people in place and working as we speak -> goal is a note at least by end of this year; also need more studies of electron signal definition (radial, topological clustering, corresponding noise suppression strategy, etc. ) -> very different signal characteristics! validation of electromagnetic (arrows indicate selection with “best” linearity) energy scale in ATLAS FCal: no tracking available, weak constraint from transverse energy balances, but maybe Z->ee can help? Need to address e/jet separation etc. in this case…