1. From Hadronic Energy Scale to Jet Energy Scale
ATLAS Hadronic Calorimeter Calibration Workshop
MPI, Munich, May 3-5, 2006
May 3, 2006
Peter Loch
University of Arizona
Tucson, Arizona 85721
From Hadronic Energy Scale to Jet Energy Scale
Peter Loch
University of Arizona

2. Maybe we should try to factorize as much as possible?
ATLAS Hadronic Calorimeter Calibration Workshop
MPI, Munich, May 3-5, 2006
May 3, 2006
Peter Loch
University of Arizona
Tucson, Arizona 85721
Local calibration provides a hadronic energy scale, but in NO WAY a jet energy scale (I really insist on this difference!)!
jets are somewhat badly defined in the detector -> the calorimeter distorts the jet shape (includes calorimeter signal definition, clustering, possible noise cuts, etc.), for example…
jets are often viewed at in the context of a given physics analysis –> in some cases a so-called electron may actually be viewed at as a jet without necessarily changing the calibration of this particular object!
jet algorithms may cut into the signal, or include noise, underlying events, pile-up, remnant activity -> whoever says we always have to use the inclusive kt, for example??
jet signals are clearly depending on additional activity in a physics event -> very different for QCD di-jets (color coupling between jets, underlying event, pile-up) and SUSY events (high multiplicity in jets, electrons, photons, muons,…);
Maybe we should try to factorize as much as possible?
we have to keep track of systematic errors anyway!

3. Ingredients to Jet Reconstruction in the Calorimeters
ATLAS Hadronic Calorimeter Calibration Workshop
MPI, Munich, May 3-5, 2006
May 3, 2006
Peter Loch
University of Arizona
Tucson, Arizona 85721
Ingredients to Jet Reconstruction in the Calorimeters
longitudinal energy leakage
detector signal inefficiencies (dead channels, HV…)
pile-up noise from (off-time) bunch crossings
electronic noise
signal definition (clustering, noise suppression algos,…)
dead material losses (front, cracks, transitions…)
detector response characteristics (e/h ≠ 1)
added tracks from in-time (same trigger) pile-up event
added tracks from underlying event
lost soft tracks due to magnetic field
physics reaction of interest (parton level)

4. ATLAS Hadronic Calorimeter Calibration Workshop
MPI, Munich, May 3-5, 2006
May 3, 2006
Peter Loch
University of Arizona
Tucson, Arizona 85721

5. Towards jet energy scale - today’s session:
ATLAS Hadronic Calorimeter Calibration Workshop
MPI, Munich, May 3-5, 2006
May 3, 2006
Peter Loch
University of Arizona
Tucson, Arizona 85721
Towards jet energy scale - today’s session:
Mark on particle level jet composition and magnet effects
Ambreesh on calibrated
topoclusters in jets
Rolf on “em tagging” of jets

6. Energy scale of (general) hadronic final state
ATLAS Hadronic Calorimeter Calibration Workshop
MPI, Munich, May 3-5, 2006
May 3, 2006
Peter Loch
University of Arizona
Tucson, Arizona 85721
Energy scale of (general) hadronic final state
use of local hadronic calibration in missing Et calculations (Silvia)
in the context of general use of refined calibration of any physics or reconstruction objects;
alternative: numeric weighting approach (Elin & Cigdem)
similar to yesterday’s talk;
alternative: radial distance weighting (Malachi Schram, Ottawa)
first application of weights calculated from testbeam data to simulated jets -> slides;
FCal only?

7. Plots by Malachi Schram, Carleton University
ATLAS Hadronic Calorimeter Calibration Workshop
MPI, Munich, May 3-5, 2006
May 3, 2006
Peter Loch
University of Arizona
Tucson, Arizona 85721
Plots by Malachi Schram, Carleton University
(as of Nov. 2005)
Very preliminary!
Very preliminary!
Radial weighting is very intuitive wrt hadronic
shower development;
Weights can be extracted from testbeam data
without any use of Monte Carlo (at least relative,
absolute scale still needs leakage estimates etc.);
Originally studied by A. Savine with 1998 data,
now studied for 2003 data by M.Schram;
Very preliminary!

8. Plots by Malachi Schram, Carleton University
ATLAS Hadronic Calorimeter Calibration Workshop
MPI, Munich, May 3-5, 2006
May 3, 2006
Peter Loch
University of Arizona
Tucson, Arizona 85721
Straight forward application of radial weights determined from experimental testbeam pions to simulated (+ electronic noise) jets in ATLAS – no further optimization, “wrong” normalization of the weights to beam energy etc…
Very preliminary!
Very preliminary!
Plots by Malachi Schram, Carleton University
(as of Nov. 2005)

9. Not really addressed today…
ATLAS Hadronic Calorimeter Calibration Workshop
MPI, Munich, May 3-5, 2006
May 3, 2006
Peter Loch
University of Arizona
Tucson, Arizona 85721
Not really addressed today…
consistent and detailed look at factorization of jet energy scale corrections
JES – Jet Energy Scale
LHS – Local Hadronic energy Scale, includes cluster level dead material corrections
DMC – additional Dead Material Corrections (not clear that cluster based corrections
are sufficient!);
JAC – Jet Algorithm Corrections (out-of-cone, Kt “garbage collection”,…)
UEC – Underlying Event Corrections - we are getting gamma+jet(s) with different
phase space for UE! (finally!)
DAC – Detector Acceptance Corrections (longitudinal leakage “tagging” and correction…)