The UIUC ATLAS TileCal Project

1
The UIUC ATLAS TileCal Project
Project Head - Dr. Steven Errede

• Niall Nethercote
• UIUC High Energy Physics
• Summer 1998

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Contents

• Background on Experimental Particle Physics
• The World-Wide ATLAS Project
• The UIUC ATLAS TileCal Project
• Sub-Module Fabrication
• Photomultiplier Tube (PMT) Testing
• Our Web Site

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Experimental Particle Physics
Topic 1
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Particle Accelerating Facility

• Accelerating Ring
• Detector

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How is a Particle Detected?

• Accelerate some matter (e.g. the quarks of
  protons)
• Collide the quarks (and get a mess of gluons)
• Interesting particles may form (e.g. top quark)
• Detect the residual particles (e.g. w/ a PMT)

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The World-Wide ATLAS Project
Topic 2
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CERN

• CERN is the European Laboratory for Particle
  Physics
• CERN is located in both France and Switzerland
• It is very near Geneva, Switzerland

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Enlargement of the LHC
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The LHC Project

• CERN is upgrading in three major ways

• Large Hadron Collider (LHC) Ring
• Compact Muon Solenoid (CMS) Detector
• A Toroidal LHC Apparatus (ATLAS) Detector

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The ATLAS Project

• 144 institutes world-wide are collaborating on
  the ATLAS project
• ATLAS is 5 stories tall!
• ATLAS will detect proton-proton collisions
• Its center of mass energy is 14 TeV!
• ATLAS will start taking data in 2005

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The UIUC ATLAS TileCal Project
Topic 3
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UIUC and ATLAS

• What part of ATLAS does the UIUC group work with?

• The Scintillating Tile Hadron Calorimeter
  (pictured green)

• Sub-modules are made of alternating layers of
  steel and scintillating tile (shown in next
  slide)
• Groups of sub-modules are modules
• Groups of modules form the Hadron Calorimeter

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What Does the UIUC Group Do?

• The UIUC ATLAS project is two-folded
• Sub-Module Fabrication
• Photomultiplier Tube (PMT) Testing

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Hadron Detection

• How are hadrons detected with sub-modules and
  PMTs?
• Hadron flies through scintillating tile and
  photons are released
• Fiber optics route some photons to a PMT
• Photons hit PMT and convert to photoelectrons
  (via photoelectric effect)
• Electrons are multiplied inside PMT and a
  detectable signal results

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Sub-Module Fabrication

• UIUCs sub-module assignment
• Glue machine
• Prototype sub-module production

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The Sub-Module Assignment

• UIUC is responsible for producing 200 extended
  barrel sub-modules

• In the extended barrel 9 sub-modules make up a
  module (and also recall that there are 64 modules
  circling around the beam axis)
• So when you do the math it turns out that we are
  making about 1/3 of an extended barrel

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Glue Machine

• The glue machine will be used to apply very
  precise amounts of glue to the sub-modules
• It is currently being constructed and will be
  ready for early 1999 when we begin to make some
  more sub-modules
• Dr. Errede and Fred Cogswell (our machinist) have
  put the most work into the glue machine

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Sub-Module Prototype Production

• During the Winter of 1996-1997 we constructed
  some prototype sub-modules

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Photomultiplier Tube (PMT) Testing

• General
• UIUCs PMT testing assignment
• Our PMT testing setup
• The work that we did this summer
• Dark Box modification
• PMT Aging experiments

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The PMT Testing Assignment

• When ATLAS begins data taking it will be using
  approximately 10,000 PMTs!
• Here at UIUC it is our job to test over 3,000 of
  those PMTs (i.e. about 1/3 of ATLASs PMTs)

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Our Laboratory

• Here is a shot of Dr. Erredes Laboratory

• Note the crates and the dark box

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Our Dark Box

• Here the crates are on the left, the dark box is
  on the right, and thats Jori walking into the lab

• The mess of wires that run in and out of the dark
  box
• The dry nitrogen system can also be seen

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Inside the Dark Box

• This is our PMT testing layout that is housed in
  the dark box

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Dark Box Modification

• Our group needs to prepare for the testing of the
  over 3,000 PMTs
• The biggest task is modifying the dark box so
  that it can test 30-40 PMTs at one time
• The dark box modification projects are
• Adjusting the layout of the dark box
• Stepper Motor
• Filter Wheel
• Increasing the amount of light to the Photodiode
• Faster Transistor for the Pulsing Circuit
• Charge Cable
• Optics

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The Stepper Motor

• The stepper motor will be used to move components
  around inside the dark box
• Before this summer Jori Ruppert-Felsot worked
  with the stepper motor

• Then when the summer began John Patti and Mike
  Griswold finished up the task

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The Filter Wheel

• The filter wheel will be used to vary the
  intensity of the light goes to the PMT
• The stepper motor will rotate the filter wheel

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The Photodiode Needs More Light

• Three different attempts at supplying the
  Photodiode with more light have been attempted
  this summer
• Mainly Jori Ruppert-Felsot, Dan Dombeck, and I
  have been working on this
• For the most part all attempts have been
  unsuccessful
• Using a faster transistor or a circuit that
  incorporates two transistors
• Hooking a charge cable up to the LED
• Setting up an optics system that can focus light
  onto the Photodiode

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PMT Aging Experiment

• About one month ago we received a new 4th
  generation PMT (8C28R3) from CERN
• We proceeded to test its aging characteristics
• The new PMT was pulsed at a number of different
  frequencies for one week
• The tests on this PMT ran for time intervals of
  approximately 24 hours
• During our testing, the PMT experienced an
  equivalent of 50 years of running at ATLAS
• Important Quantities Npe and the Gain

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PMT Aging Experiment Results
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PMT Aging Experiment Results
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Conclusions and Then Continuation

• We concluded that the gain of the new 4th
  generation PMT actually increased slowly while it
  was being pulsed for 50 equivalent years
• This is rather odd. The PMTs performance is
  seemingly improving as it ages?!
• Possible explanation charge may be collecting on
  the walls of the PMT, thus creating an electric
  field that focuses the e-
• We then proceeded to perform more aging
  experiments on older 3rd generation PMTs that we
  had available in our lab

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The UIUC ATLAS TileCal Web Site
Topic 4
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A New Look

• During the middle of the summer I completely
  revamped our ATLAS Web Site
• The URL for our Site ishttp//web.hep.uiuc.edu/
  atlas/
• But lets first check out what the Old Site looked
  like

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Thank Yous

• I would like to thank the following people for
  teaching me so much this summer

• Jori Ruppert-Felsot

• John Patti
• Mike Griswold

• Daniel Dombeck

• And especially

• Dr. Steven Errede

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The Musings of John Patti

• This was Johns reaction when I told him how much
  work I was going to put into my presentation