ATLAS Tile Hadron Calorimeter at UIUC

1
ATLAS Tile Hadron CalorimeteratUIUC

• Dave Petersen, North Park University
• Working under HEPG Prof. Steve Errede

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What, Who and Where?

• A Toroidal Large Hadron Collider Apparatus
  (ATLAS) Detector
• Over 30 countries involved, from Armenia to the
  United States (over 30 U.S. institutions are
  participating)
• To be built at CERN, near Geneva, Switzerland

3
What is the LHC?

• A proton will be colliding with another proton
• Will achieve energy of 14 TeV, most energetic
  collider in the world

4
ATLAS A Five Story Detector

• Red line is the beam pipe
• Pink is the tracking detector
• Gray is the Solenoid Magnet
• Yellow is the Electromagnetic Calorimeter
• Green is the Hadron Calorimeter
• Gray tubes are muon torodial magnet
• Blue is the muon detector

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What is UIUC doing for ATLAS?

• UIUC is one of 5 institutions working on the
  Scintillating Tile Hadron Calorimeter
• Produce 200 full-size Submodules
• Test 3,000 Photomultiplier Tubes

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What is a Module?

• 64 Full Modules required for TileCal
• Each Module is composed of 8 full-size
  submodules, one half-size and one quarter-size.

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How does the TileCal work?

• Steel absorbers separated by tiles of
  scintillating plastic
• When the Hadronic shower, hits the scintillating
  tiles, they emit light in an amount proportional
  to the incident energy
• Fiberoptics connected to the tiles carry the
  light to PMTs

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Production of Submodules

• UIUC wants to finish production by May of 2002
• Currently have 49 complete
• Looking to improve efficiency of operations-one
  of the biggest problems is the cleaning of the
  plates that has to be done by hand
• Over 10 miles of steel required for 192 submodules

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Quality Steel from the Czechs

• Notice the grease on these plates
• Every single plate must be washed by hand
• There are 192 spacers plates and 32 master plates
  per submodule that must be washed

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Stamped, Not Laser-Cut

• Spacers are .004 in. thinner than design
  qualifications
• The TileCal design calls for submodules must be
  within .002 in.
• So we place .004 in. stickers on each individual
  spacer before we glue

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Gluing

• Takes a little over 2 hours to stack and glue one
  submodule
• Use glue machine which requires over 8,000 lines
  of code
• Prof. Errede desires to break the 2 hour barrier
  (his own version of the 4 minute mile)

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Quality Control

• After welding, various measurements must be taken
  to ensure that each submodule meets the design
  requirements
• We must also check each individual slot for the
  tiles to make sure the tiles will fit

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Analysis of Quality Control

• Here is a 3D graphical view of the average
  submodule heights broken up by points

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Painting - In order to rustproof

• Toxic paint from the Czech Republic is used to
  rustproof the submodules
• Takes over 3 days to dry
• Excess paint must be ground off

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Chaotic Paint?

• Heres what the rustproof paint does to the steel
  after 3 days

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Ready to Ship

• These submodules are ready to go to Argonne,
  where they will be assembled into a full module

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Quality Control

• After welding, various measurements must be taken
  to ensure that each submodule meets the design
  requirements
• We must also check each individual slot for the
  tiles to make sure the tiles will fit

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3 Kinds of Measurements

• Height
• Perpendicularity
• Bolt Holes

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QC Man

• Claremont suggests a designated QC Man

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QC Analysis

• Graphs up the wazoo!!

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QC - Height

• Design Height 291.7 0.3 -1.5 mm

• All within design tolerances

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QC - Height

• QC Sheet

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QC - 3D Model

• Tack Weld

• Load plate causes sloping

• Final Weld

• Final weld causes shrinking at the corners

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QC - Perpendicularity

• QC Sheet

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QC - Perpendicularity

• UIUC Submodules tend to be perpendicular at all
  points

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QC - Bolt Holes

• Design Separation for Bolt Holes from one weld
  bar to the other is 325.00 /- 0.2 mm

• Design Bolt Hole Height on each weld is 110
  /-0.2 mm

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QC - Bolt Holes

• Weld bars pulled in after final weld

• UIUC tends to produce submodules that have weld
  bars which are slightly off center - about 0.2 mm
  below the center of the submodule

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Production Status

• 62 done, only 130 more to go!!

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What will ATLAS show us?

• The measurements taken using ATLAS will hopefully
  help explain these theories
• Higgs Particle and Field
• Grand Unified Theory

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Higgs Particle and Field

• Higgs field is almost indistinguishable from
  empty space
• All of space is filled with this field, and that
  by interacting with this field, particles acquire
  their masses.
• Particles that interact strongly with the Higgs
  field are heavy, while those that interact weakly
  are light.

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Grand Unified Theory

• Physicists hope to unify the weak, strong, and
  electromagnetic interactions

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PMT Testing

• UIUC will perform test on the PMTs that will
  measure
• PMT Performance
• PMT Rate Dependence
• PMT Drift/Stability/Aging Studies

• UIUC will receive testing boxes shortly

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Test Each PMT Twice

• Using LabView, UIUC will test each Hamamatsu
  R-7787 PMT twice, once in the Dark box and once
  in the Light box
• Test 1 will use DC Light
• Test 20 PMTs per 2 days
• Test 2 will use Pulsed Light
• Test 20 PMTs per day

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What Ive Learned

• Multi-national project has just as many
  disadvantages as advantages
• Lab Machinists are a rare kind of people (see
  next slide)
• Hands-on physics is for me

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Thanks To

• Dr. Steven Errede
• Dave Forshier
• Henri Cordier
• And Fred Cogswell, who when left the project gave
  this farewell