the atlas tile calorimeter muon studies at 90° presented at cern by michael borysow for the...
TRANSCRIPT
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
Tile Calorimeter Description What is Calorimetry? Specifics to the Atlas Tile Calorimeter
My Analysis Muons at 90 Degrees Discoveries
Conclusions
Atlas Overview Four Major Components
Inner Tracker Calorimeter – Electromagnetic Calorimeter – Hadronic Muon Spectrometer Magnet System
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 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 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.
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.
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.
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.
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.
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.