Early Commissioning of ATLAS

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Early Commissioning of ATLAS

• First North American ATLAS Physics Workshop
• Tucson

J. Pilcher University of Chicago
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Early Commissioning of ATLAS
10 Dec 04
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Commissioning Goals

• Establish operation of full systems
• Readout
• Calibration systems
• Low Voltage, High Voltage
• Control and Monitoring
• Cryogenics, Gas, Cooling
• Establish initial calibrations
• Mev/ADC count
• Alignment and timing
• Chamber or sensors within a detector system
• Relative alignment and timing of different
  detector systems
• Demonstrate performance levels
• Noise levels
• Physics signals

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Commissioning Stages

• Calibration systems only
• Cosmic ray muons
• MIP signals and inelastic interactions
• Stand-alone detector systems (2005-6)
• Full ATLAS detector (2007)
• Initial beam operation
• Single beam operation
• Beam-gas interactions
• Beam halo muons
• Beam-beam operation
• Minimum bias interactions
• Early beam-beam collisions
• Use physics signals ( , ?-j, Z-j,
  j-j, )

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• This talk
• Concentrate on first three stages
• Other talks on commissioning with beam-beam
  physics signals
• Special emphasis on calorimeter systems
• More details at
• Tatra Workshop
• http//agenda.cern.ch/fullAgenda.php?idaa041267
• Overview week at Freiburg commissioning session
• http//agenda.cern.ch/fullAgenda.php?idaa041780s
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• Overview week at Prague commissioning session
• http//agenda.cern.ch/fullAgenda.php?idaa03190s2
  
• This talk draws on the work of many people
• R. Teuscher, R. McPherson, J. Huston,

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• Preliminary commissioning already being done
• Combined test beam in 2004
• Tilecal operation on cosmic muons in Bldg. 185
• LAr operation on cosmic muons in Bldg. 180
• Muon chamber operation with cosmics
• TileCal barrel on HF truck in UX15
• Commissioning is iterative with larger scale
  integration at each step

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Now TileCal Commissioning on HF Truck in UX15
Record data from UX15 testing TTC, CANbus, HV,
laser fibres via LED, BCID _at_ 100 kHz L1A, CIS,
readout noise,
Charge Injection Pulses OK
Noise Test OK
RMS (ADC counts)
Photo from September 28, 2004
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• Barrel calorimeters move to z0 August 2005 when
  BT is assembled
• Detectors fully assembled and equipped with
  on-detector electronics
• Connect to services
• Stand-alone commissioning with calibration
  systems
• Eg. for TileCal (1/2 the system)
• Charge injection to all readout channels (4K in
  barrel)
• Cesium source activates tiles and fibers (220K in
  barrel)
• Laser system activates each PMT (4K in barrel)
• First large-scale detailed commissioning

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Charge Injection Calibration of TileCal

• Pulse individual channels over full dynamic range
• establish gain, linearity, stability

Uncorrected channel-to-channel uniformity RMS
1.3 counts/pC (1.6)
Gain variation over 4 months of CTB RMS 0.2
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Cs Calibration of TileCal

• Cs-137 source illuminates individual tiles
• Stainless tubes pass through all tiles in the
  system
• Source capsule driven through tubes hydraulically
• Single tile response measured at 2 level
• Cell response measured at 0.3 level
• Week-to-week variations in cell response 0.5

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Cosmic Ray Commissioning

• Full G3 simulation done by Rob McPherson and
  Pavel Nevski

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Cosmic Ray Commissioning

• Rates are substantial
• 2.3 KHz for a hit anywhere in detector
• 0.5 Hz for Z
• Natural to trigger with muon system RPCs
• Global ATLAS cosmic muon run planned for 40 days
  in April 2007 before LHC starts
• Attractive to run barrel calorimeters on cosmics
  from late 2005
• Before RPCs available
• Evaluated trigger using TileCal
• back-to-back trigger towers

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TileCal Response to Muons

• Test beam data for 180 GeV muons at ?0.05
• Energy depends on path length through calorimeter
• 1K muons in a tower gives response to 1

Tower Energy (pC) (1.1 pC/GeV)
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TileCal Cosmic-Muon Trigger

• Consider back-to-back TileCal towers
• ?? x ??0.1 x 0.1, full calorimeter depth
• Especially useful because tracks pass close to
  interaction point
• Analyze McPherson/Nevski simulation for rate and
  event properties
• S. Zenz (Chicago undergraduate)

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TileCal Cosmic-Muon Trigger

• Require 2 back-to-back towers with E 1.5 GeV
• Lower peak corresponds to additional towers
  struck (corners clipped)

Rate is 130 ?/hr for 16 top 16 bottom
modules in coincidence 100K / month
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TileCal Cosmic-Muon Trigger

• Effect of PX14 shaft is
• clearly seen

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Typical Events
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Typical Events (2/2)
Example of muon scattering in detector
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Muons in LAr Barrel
Due to Accordion geometry, muons are
reconstructed in middle compartment by summing
two cells in ?.

• With 100 events muon signal in LAr can be
  measured with
• 3 precision
• For first shake-down
• Could use cosmic ray muons to measure first LAr
  physics pulse shapes and compare to calibration
  pulses.
• Useful to reconstruct combined muons in LAr
  TileCal to match EM energy scale and timing.

Note S/N ratio too small in strip and back
compartments
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Muons in LAr Using TileCal Trigger

• TileCal Trigger tower size (0.1?0.1) corresponds
  to 4?4 LAr middle cells
• Resulting maximum non-projectivity ? 3º, muons
  can cross at most 2 cells in ? and in ?
• ? non-projectivity probably not a problem, due to
  natural sharing between ? cells (two cells are
  summed)

• Studies of rate in LAr using TileCal cosmic
  trigger (back-to back towers) by Philippe
  Schwemling and Emmanuel Monnier.
• Est. 6 months run

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With 100 muons/cell in middle compartment

• Check calorimeter timing to optimal filtering in ROD
• Check calorimeter position in ? / ? wrt other
  sub-detectors to

Test-beam data

• 1 precision measured with 1000 ?
• with 5000 ? 0.5 precision
• ( 100 ? /cell integrated over ?)

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Hardware Needed for TileCal Cosmic Trigger

• Electronics drawers in barrel (128)
• LV power (in TileCal fingers)
• Bulk LV power (200V for USA15)
• Cabling and fibers
• TTC hardware
• Standalone clock
• LVL1 trigger interface hardware
• Patch panels to separate tower and muon signals
• Receiver boards (64 towers each)
• Initially use custom trigger logic for cosmic ray
  running
• ROD/LVL2 hardware
• ROD modules, ROD crate and controller (ROD crate
  DAQ)
• Output hardware from ROD crate to PC via Ethernet
• Later use ROBIN/ROS

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TileCal Muon Trigger Logic

• LVL1 trigger not designed to run on back-to-back
  muons
• Adapting it would be a diversion
• Also scheduled to arrive late compared to initial
  stand-alone calorimeter operation
• Build some simple coincidence logic

• Test by injecting muon signal into trigger tower
• Vary tower threshold and check efficiency

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Time Table for Cosmic Ray Commissioning

• TileCal barrel complete Mar-06 (following
  checkout)
• Stand alone operation begins
• LAr barrel complete Aug-06 (following checkout)
• Stand alone operation begins
• Global commissioning Dec-06 through Feb-07
• ATLAS cosmic run
• Mar-07 through Apr-07
• ATLAS ready for beam 4/27/07

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First commissioning with single beam

• Beam halo muons
• Generated by machine group
• Simulated in ATLAS
• Beam gas events

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A typical beam-gas event
Beam-gas collisions are essentially boosted
minimum-bias events ? low-pT particles
Rate 2500 interactions/m/s
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Beam-gas Rates Properties
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Beam Halo Muons
Especially useful for endcaps and ID disks and
wheels
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Beam-Halo Rates

• Estimate rates for 200 times less current than
  design
• Totals in table for 2 month run at 30 efficiency

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Triggering on Beam Halo and Beam-Gas events

• Minimum-bias scintillators being added in front
  of LAr end caps
• z 3.5 m
• 14 cm
• 1.9
• 8 channels in ?, 2 channels in ?
• Readout via TileCal electronics drawer

Joey Huston is project leader on this.
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Conclusions

• Good prospects for progressive commissioning
  process
• Stand alone detector systems with calibration
  systems and cosmic muons
• Global detector with cosmic muons
• Beam halo muons and beam-gas events in early 2007
• Minimum bias beam-beam interactions by mid 2007
• Fully simulated samples of cosmic muons,
  beam-halo muons and beam gas events exist
• R. McPherson et al.
• Final commissioning phase will be with physics
  signals
• Essential for final tune-up
• Essential for showing we understand the detector
  behavior