The Atlas Tile Calorimeter

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The Atlas Tile Calorimeter

• Muon Studies at 90

Presented at CERN by Michael Borysow for the
University of Michigan REU Program
14/08/03
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Outline

• Tile Calorimeter Description
• What is Calorimetry?
• Specifics to the Atlas Tile Calorimeter
• My Analysis
• Muons at 90 Degrees
• Discoveries
• Conclusions

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Atlas Overview

• Four Major Components
• Inner Tracker
• Calorimeter Electromagnetic
• Calorimeter Hadronic
• Muon Spectrometer
• Magnet System

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What is Calorimetry?

• Calorimetry refers to the detection of particles
  through total absorption in a block of matter.
• Calorimetry is a destructive method.
• The only exceptions being muons.
• Muons can penetrate substantial amounts of mass
  represented by the calorimeter, thus they become
  IDd as muons.
• True Calorimeters measure the total energy of a
  particle and are made of a single substance, such
  as Germanium or NaI crystal.
• The Atlas Tile Calorimeter is a Sampling
  Calorimeter.

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Sampling Calorimeters

• Sampling Calorimeters are made of more than one
  substance
• Active Medium
• Generates light or charge that forms the basis of
  the calorimeter signal
• Passive Medium
• Absorbs energy
• In Sampling Calorimeters, only a small fraction
  of the energy is deposited in the active medium.
• The advantage of a Sampling Calorimeter is that
  it is much cheaper and smaller.
• The goal is still to stop the particle, and the
  passive medium can help do this much more quickly.

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Benefits of a Calorimeter

• Calorimeters, with tracking data, allow for
  effective identification of particles.
• Can measure the energy of neutral particles,
  whereas a magnetic spectrometer cannot.
• Fast Response time Can be used as a trigger for
  other detector components.

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The Tile Calorimeter

• Made of 64x4 submodules
• Two Long Barrels
• Two Extended Barrels
• Each submodule is composed of alternating tiles
  of polystyrene and steel separated into 11 tile
  rows.
• Polystyrene is the active medium, while steel is
  the passive medium.

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Long Barrels
Extended Barrels
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The Tile Calorimeter

• Polystyrene acts as a scintillating material.
• Through various processes, molecules and atoms
  will become excited, and then emit light when
  they drop to the ground state.
• The scintillation light is picked up by
  wavelength shifting fibers (WSF) and carried to
  Photo Multiplier Tubes (PMTs).
• The PMTs then produce an electronic signal, which
  is digitized and sent to the Data Acquisition
  Systems.

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Cell Layout

• Each cell can be read out individually in two
  channels.
• Each cell has WSFs which on either side. These
  fibers carry the light to the PMT.
• WSFs are used, because the light emitted by the
  scintillation process is 100 nm. The PMTs are
  most sensitive around 550nm.

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Studies at 90

• Studies at 90 degrees are used to check tile row
  uniformity.
• Muons are made use of for the reason that they
  deposit the roughly the same energy in each cell
  (per Tile) as they pass through the detector.
• Thus, muons are useful for detecting bad
  equipment.

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Tile Row Uniformity
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Channel Uniformity per Row
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Channel Summary
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Distribution of Channel Response
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Geometry Problems?

• Currently investigating possibility of
  misalignment of the test setup.

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Acknowledgements

• Jean Krisch, Homer Neal, and Tom Dershem
• My Adviser, Richard Teuscher
• The Argonne Boys
• University of Michigan
• National Science Foundation
• Ford Motor Company