Transcript The Atlas Tile Calorimeter - Web Lecture Archive Project

The Atlas Tile Calorimeter
Muon Studies at 90°
Presented at CERN by Michael Borysow for the
University of Michigan REU Program
14/08/03
Outline
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Tile Calorimeter Description
What is Calorimetry?
 Specifics to the Atlas Tile Calorimeter
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My Analysis
Muons at 90 Degrees
 Discoveries
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Conclusions
Atlas Overview
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Four Major Components
Inner Tracker
 Calorimeter – Electromagnetic
 Calorimeter – Hadronic
 Muon Spectrometer
 Magnet System
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What is Calorimetry?
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Calorimetry refers to the detection of particles through
total absorption in a block of matter.
Calorimetry is a destructive method.
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The only exceptions being muons.
• Muons can penetrate substantial amounts of mass
represented by the calorimeter, thus they become ID’d 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.
Sampling Calorimeters
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Sampling Calorimeters are made of more than one
substance
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Active Medium
• Generates light or charge that forms the basis of the
calorimeter signal
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Passive Medium
• Absorbs energy
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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.
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The goal is still to stop the particle, and the passive medium
can help do this much more quickly.
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
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Made of 64x4 submodules
Two Long Barrels
 Two Extended Barrels
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Each submodule is composed of
alternating tiles of polystyrene and
steel separated into 11 tile rows.
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Polystyrene is the active medium, while
steel is the passive medium.
Long Barrels
Extended Barrels
The Tile Calorimeter
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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.
Cell Layout
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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.
Studies at 90°
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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.
Tile Row Uniformity
Channel Uniformity per Row
Channel Summary
Distribution of Channel Response
Geometry Problems?
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Currently investigating possibility of
misalignment of the test setup.
Acknowledgements
Jean Krisch, Homer Neal, and Tom
Dershem
 My Adviser, Richard Teuscher
 The Argonne Boys
 University of Michigan
 National Science Foundation
 Ford Motor Company
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