MayaMuon Tomography at UTAustin

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Maya-Muon Tomography at UT-Austin

• A most awesome albeit brief presentation by
  Derrick L. Tucker

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This is applied particle physics!

• As opposed to those other presentations of
  fundamental particle physics.

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Cosmic-Ray Muon Tomography

• What is it exactly?
• It is effectively the use of a particle detector
  to track cosmic-ray muon rates for the purpose of
  computer-assisted image reconstruction.

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In our case we track muon count rates at a
variety of different angles and locations.
Differences in the rates from different
directions indicates that the total mass of
material along these directions is thus
different, which we can then use, in theory, to
create tomographic images.
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Why use muons for tomography?

• Reason 3 - Relatively speaking, they live to a
  ripe old age!

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Why else?

• Reason 2 - Taking into account time-dilation,
  muons thus reach sea-level at an approximate rate
  of 10,000 muons per square meter per minute.

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The Final Reason

• And Reason 1 - Energy loss is predominately by
  ionization and thus is quantifiable.

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A brief aside, but where do these muons come from?

• In the atmosphere, muons are produced as the
  secondary decay products of mostly protons (sent
  from countless explosions and other such
  activities beyond our solar disc) interacting
  with nuclei in the atmosphere. These
  interactions produce pions and kaons, the charged
  variety of which then decay into muons.

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Illustrative Diagram of Muon Production from Pion
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The Detector Herself

• Isnt she beautiful!

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One more picture, complete with beautiful people!
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General Detector Structure
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Scintillator

• Extruded polystyrene
• Fluoresces when a charged particle passes through
  it
• Coated with white paint to contain light within
  the strip
• Carries a groove down the center to house WLS
  fiber

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FEBs/PMTs

• The PMTs collect light from the WLS fibers and
  feed these via the circuit board to the front-end
  boards (FEBs) in order to digitize the
  information.

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3 Types of FEB signals

• Synch
• Configuration
• Data-Transfer

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And then . . .

• All these signals then get routed to the Compact
  Rio (or simply the Rio), which adds timing
  information in the form of a 40 Mhz clock before
  feeding said information to an external computer.

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The Detector, the Muon, and the Pyramid
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Basic Scheme

• Muons travel through atmosphere
• Muons interact with the rock/ground/pyramid
• Muons then strike the detector
• Hits then get counted and (eventually)
  reconstructed into an image

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Current Work

• In order to track muon events we are critically
  interested in discerning triplets.
• A triplet is simply a series of hit strips, one
  on each layer, that overlaps at a point.

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Discerning Triplets

• An event is determined by two triplets, an entry
  triplet and an exit triplet.

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Offline Software

• The offline software, post-Rio, is used at this
  point to reject spurious events and noise and,
  through algorithms outlined in my term paper,
  determine the best entry and exit triplets. The
  quantity describing the best triplets is the
  quantity, with a lower value representing a
  better triplet.
• For more information please read my stellar term
  paper . . .

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Offline Software Cont.

• Offline software is developed using C
  preliminarily in MatLab before being ported and
  updated in Geant4, a toolkit developed at CERN
  for particle interaction simulation.

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2-D Triplet Display
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Current Work Part DuexTriplets and Doublets

• Our most current work (i.e. this past weekend
  current) involves resolving triplets and doublets
  in order to increase number of events we can use
  to reconstruct events.

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Triplet/Doublet Discernment

• There must be one triplet associated with said
  doublet.
• The triplet strike must be clean, that is to
  say that not many associated strips can be struck.

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Future Goals

• Finish detector construction
• Continue testing triplet algorithms and (very
  soon) do some rudimentary test imaging
• Go to Belize and image the internals of Mayan
  pyramids

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And . . .

• Party in BELIZE!!!

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THE END!

• For now . . .