Status/Plans for EM Calibration S. Rajagopalan July 13, 2006 ATLAS Week, Stockholm

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 2 Outline  Summarize the present calibration in Athena  Cell and Cluster level corrections  Short term updates (plan for )  As-built detector simulation  Plans for calibration data challenge.

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 3 Cell level calibration E = (ADC   A) * (  A  GeV) * ∑ a i (ADC i – ped)   a i = Optimal filter coefficients   ADC   A  ADC  DAC from electronic calibration (“Ramp”)  Mphys/Mcal correction of amplitude bias calibration-physics pulse  DAC   A injected current from calibration (~1/Rinj)    A  GeV derived from Test-Beam data  Includes the sampling fraction  Can also be decomposed from fSampl*(MeV/  A)_Lar  This decomposition relies on fSampl from Geant4  For EMEC: MeV/  A = MeV/  A_0 * b /(1+a(  -  0) )  a, b derived from TB data  Current digitization/reconstruction uses sampling fraction derived from simulation, the rest from TB02 measurements

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 4 Cell Level Calibration (2)  Calibration applied at ROD and HLT would probably be simpler.  Studying the possibility to apply “linear calibration” at the RODs and applying a refined higher order electronics calibration and correcting for pedestal shifts during offline reconstruction.  HV corrections (dead on one side or non-nominal)  Corrections for pathological cells (noisy, dead)  Correction for temperature variation  Correction for argon purity  Inter-calibration between calorimeter regions obtained from Z analysis.  Most of these have yet to be implemented in the current reconstruction.  But the software structure allows for easy plugi-in’s of correction tools

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 5 Cluster Level Corrections  Two clustering algorithms are used:  Sliding Window algorithm producing EM clusters in 5x5, 3x5, 3x7  Topological clustering with seed 6,3,0  Being studied for e-gamma reconstruction..  Sliding Window clusters are corrected for:  Eta and phi position corrections  Energy modulations vs eta, phi  Lateral out of cone energy corrections  Longitudinal corrections including upstream matter & leakage  Gap corrections, if relevant  Correct for residual HV effects and pathological cells.  Overall energy scale  Corrections in all derived from DC2 single electrons

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 6 S-shape corrections Finite granularity of middle sampling (0.025x0.025) not small compared to shower width Simple energy weighted position (  ) measurement pulled toward middle of cell Corrections derived from single electrons (Snyder) Snyder

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 7 Energy modulation Energy modulations as a function of phi Derived for different eta positions Energy modulations as a function of eta Derived for different cone sizes and eta bins 0.1 to 0.2% effect S. Snyder

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 8 Longitudinal weights Different parametrization in gap region (gap scintillator energy is used): Weights extracted via a chi 2 fit on single electrons (S. Paganis) Weights extracted via a chi 2 fit on single electrons (S. Paganis)  Will be updated for with latest geometry tag: DC3-05

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 9 Longitudinal weights A more sophisticated expression has been demonstrated to improve linearity and good resolution at TB02 (T. Carli) E loss upstream of PS E loss between PS and calo calo sampling fraction+ lateral leakage E dependent Longitudinal leakage 1.5 X 0, 3.6 GeV 0.9 X 0, 4.1 GeV > 30 X 0, 0.3 GeV Better than 0.1 % over GeV:  Done only at one  position in a setup with less material than in ATLAS and no B field  Implementation of this method in Athena is being explored by L.Carminati, L. Mandelli, et. al. using “calibration hits” using “calibration hits” T. Carli

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 10 Gap corrections  Gap corrections re-derived for using gap scinitillators (S. Paganis, J. Hoffman)  No gap scintillators in early Rome reconstruction  Comparison of  E/E true in Release and : Mean = ±0.015 σ = 0.123± Mean = ±0.007 σ = 0.066±0.009 σ = 0.066±0.009 Hoffman

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 11 Performance (using simulation from x)  Slightly worse than TDR because of increased material  All corrections need to be re-derived and optimized as well. Need to use Z  ee for intercalibration of regions 448 regions in ATLAS (denoted by i) E i reco = E i true(1+α i ) M ij reco =M Z (1+(α i +α j )/2) fit to reference distribution abd propagate α i S. Paganis

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 12 Short term plan  The present release have corrections that were derived using DC2 simulation, single electrons.  These need to be re-derived as the simulation has acquired several “as-built” realistic features.  Being re-done with 11.0.x simulation, Will be available for 12.0.x  Will also need to be re-derived with 12.0.x (as-built simulation).  Corrections are also different for electrons & photons  Software infrastructure in place to implement different e-  corrections, Will try to get it in

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 13 As-built geometry in simulation  Extensive work has gone into updating the simulation with:  Material (M. Thoiye, V. Tsulai):  Solenoid supports like rails and titanium blocks.  Electronic crates mounted on barrel endcaps.  cables from the inner detector in the crack region.  radiation shielding in the FCAL region.  moderator and MBTS on the endcap.  Geometries have been thoroughly reviewed by sub-system experts  Some material on the endcap itself is not sufficiently declashed (overlapping volumes in heaters, cables, crates)  in progress for

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 14 As-built simulation (mis-alignments)  Misalignments for the barrel are in database (V. Tsulai, G. Unal).  Misalignments of large pieces:  Cryostats, EMBarrel (pos$neg), Solenoid  Translation and rotation  Typical misalignments introduced and tested.  Simulation samples generated, reconstructed – being studied (S.Laplace, R. Zitoun)  preliminary: z deplacement of cryostat 4cm reconstructed  senstivity to translation/tilt 1mm/mrad with 10k Z  Endcap misalignments pending a resolution of the cryostat issue  Sagging of electrodes and absorbers introduced (Parrour, Unal)  Establish a standard way to specify mis-alignments in DB  Will be done for (Boudreau)  Deformation (pear shape) of calorimeter NOT planned until Rel. 13

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 15 As-built simulation  Response  Decrease of the response for charge deposited close to EMEC electrode (V. Niess, G. Unal).  HV imperfections introduced; our first use of Conditions DB in simulation (V. Tsulai, G. Unal)  Calibration Hits (M. Leltchouk, G. Pospelov et. al.)  Allows saving of energy deposited in active (LAr) and inactive (absorbers) and dead material (such as upstream material) in fine granularity.  Dead material hits produced by default in Release 12.  Broken into EM, Hadronic, invisible or escaped energy deposits.  Extensively used for EM and hadronic calibration.  EM sampling fraction & longitudinal weights being studied in detail by using calibration hits (L. Carminati et.al.)  Local hadron calibration weights using calibration hits (S. Menke et. al.)

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 16 Plans for CDC  Re-derive the cluster corrections from as-built geometry in 12.0.x  Present correction are DC2 based and being re-derived with  Likely to lead to deterioration of resolution in end-cap due to increased material. Need to handle this better in reconstruction.  Simulate events with following conditions and develop procedures on how to correct for them in reconstruction  Introduce realistic misalignments between large pieces.  Electrode/Absorber sagging  Introduce mis-calibration (but perhaps can be done post-digitization)  HV pathologies  Increased up-stream matter  Effects would be studied on samples of single e, , Z  ee

ATLAS Week, Stockholm, July 2006 S. Rajagopalan 17 Concluding Remark Calorimeter Calibration Workshop, Sant Feliu, Sept. 5-8, 2006  Organized by Martine Bosman, Ilya Korolkov  Complete review of the present calibration.  Electronics, EM, Hadronic, in-situ, Trigger  Simulation, Testbeam, commissioning  Discussion on calibration strategies during early running  An “oversight panel” has been formed to closely look at our present work, help promote discussions and help us plan the road ahead:  M. Cavalli-Sforza, T. Davidek, N. Ellis, D. Froidevaux, D. Lissauer, J. Stark