Lecture 18 - Detectors

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Lecture 18 - Detectors

• Detector systems
• Momentum of charged particles (trackers)
• Energy of particles (calorimeters)
• Detector at a collider experiment.

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The purpose of a detector
e-
jet
e-
g,Z0
jet
jet
jet
jet
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Electron-proton DIS
g,Z0
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DIS event at H1 detector at HERA ep collider
(4) Muon Tracker
m-
(3) Had. Calo
jet
e- (30 GeV)
p (820 GeV)
(1) Tracker
(2) EM Calo
e-
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H1 Detector
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(1) Tracking system
m-
z
(2) EM Calo
y
(1) Tracker
x
(3) Had. Calo
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Tracker Drift Chamber
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Measuring momentum
y
x
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Measurements of ionisation energy loss
e
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Tracking Chambers
H1
Different technologies/geometric arrangements
available. Drift chambers. Time projection
chambers Semi-conductors trackers.
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Summary of trackers and some observations
m-
z
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Calorimeters

• What is the purpose of the calorimeters ?
• To measure the electromagnetic and hadronic
  energy loss separately arising from a system of
  particles.
• To measure the full energy arising from a
  collision (as much as possible). Wed like to be
  able to reconstruct what happened in the
  fundamental particle collision

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Sampling Calorimeters

• We know that particles produce some type of
  shower when they go through material (lecture
  17). Used for electromagnetic and hadronic
  calorimeters.
• Sampling calorimeter thin blocks of dense
  material interleaved with an active material
  which can measure the shower
• Many different possibilities
• Dense blocks (eg lead) interleaved with
  scintillators (for light).
• Dense blocks with liquid argon (for ionisation)
• .

Active layer
Dense material
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(2) Electromagnetic calorimeter
E0
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(3) Hadronic Calorimeter
EM Cascade
Nuclear cascade
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(4) Muon tracker
m-
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Summary so far
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Finding energetic weakly interacting neutral
particles
not measured
W-
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Missing transverse momentum from charged current
DIS data at HERA
W-
Prediction for CC cross section.
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ATLAS experiment at the LHC
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Production of supersymmetric particles at the LHC
Missing transverse momentum (simulation,
obviously)
SUSY SM Backgrounds
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Summary

• A typical collider experiment consists of
  tracking systems and calorimeters
• Many different technologies.
• Reconstruction of momentum and energy
• Particle identification.
• Weve reached the end.