Title: Particle Detectors
1Particle Detectors
Thomas Coan SMU
- What to detect?
- How to probe?
- What is a detector?
- Putting it all together
- Some examples
2Particle Properties
3General Idea of Colliding Particle Experiments
- Collide probe particles with target
- Detect particles from collision
- Interpret results
4Early Particle Physics Experiment
Ernest Rutherford 1909
Set-up
Interpretation
5How do we shoot probe particles?
- Acquire some probe particles
- Accelerate the probe particles
Final speed ? c
- Steer and aim the probe particles
6Accelerator Types
Circular
7Accelerator Types
Linear
8Target Types
Colliding beam
Fixed target
9Wave Nature of Particles
Waves interfere
Electron diffraction particle as wave
10Why use higher and higher energies?
? h/p
?The more energetic the probe, the finer the
accessible detail
11Collide
12Trajectory measurement
?Drift time ? DOCA
Magnetic field curves trajectory
curvature ? 1/p
13CLEO Drift Chamber
14CLEO Drift Chamber
15CLEO Calorimeter
- Measure particle energy (plus position and
flight path angle) - Good for charged and neutral particles
- Particles deposit energy in dense, transparent
medium - Medium produces light, proportional to particle
energy
16Scintillation
- Basic idea convert particle kinetic energy into
light
- Amount of light proportional to particle energy
- Light emission is prompt scintillators useful
as timers
- Scintillators used mostly w/ charged particles
17Sea-level muon detector
?
Discriminator
Discriminator
PMT
Scintillator
Photons enter here
Photomultiplier tube (PMT)
18(No Transcript)
19Determine production height of muons
2
1
Atmosphere
3
1
2
3
?h
Earth
- Sea level ? flux depends on pathlength from
production point
- Changing telescope angle changes pathlength
- Flux change ? production height ?h
20Cerenkov Radiation
- Emitted by charged particles only
- Emitted only when particles speed in medium
exceeds that of lights
- Pattern of light has cone-like shape
- Particles speed determines shape of cone
- Cerenkov detectors measure particle speed
- Particle momentum (mv) and speed (v) ? mass
21Cerenkov Radiation
Cerenkov radiator built here at SMU for CLEO
22Particle Fingerprints
23Russian Dolls
(Anna Kournakova?)
24Top event
25How to see neutrinosSudbury Neutrino
Observatory (SNO)
26Cerenkov Light in Action
27Sudbury Neutrino Observatory
28Summary
Variety of detector types
Detector combinations are the key
Detector behavior is understandable