1. Particle Detectors Thomas Coan SMU What to detect? How to probe?
What is a “detector?”
Putting it all together
Some examples

2. Particle Properties mass lifetime electric charge ”spin”
Thomas Coan/SMU
Quarknet 2001
Particle Properties
mass
lifetime
electric charge
”spin”

3. General Idea of Colliding Particle Experiments
Thomas Coan/SMU
Quarknet 2001
General Idea of Colliding Particle Experiments
Collide probe particles with target
Detect particles from collision
Interpret results

4. Early Particle Physics Experiment
Thomas Coan/SMU
Quarknet 2001
Early Particle Physics Experiment
Ernest Rutherford 1909
Set-up:
Interpretation:

5. How do we “shoot” probe particles?
Thomas Coan/SMU
Quarknet 2001
How do we “shoot” probe particles?
Acquire some probe particles
Accelerate the probe particles
Final speed  c
Steer and aim the probe particles

6. Thomas Coan/SMU
Quarknet 2001
Accelerator Types
Circular

7. Thomas Coan/SMU
Quarknet 2001
Accelerator Types
Linear

8. Thomas Coan/SMU
Quarknet 2001
Target Types
Colliding beam
Fixed target

9. Wave Nature of Particles
Thomas Coan/SMU
Quarknet 2001
Wave Nature of Particles
Waves interfere:
Electron diffraction: particle as wave

10. Why use higher and higher energies?
Thomas Coan/SMU
Quarknet 2001
Why use higher and higher energies?
 = h/p
The more energetic the probe, the finer the accessible detail

11. Thomas Coan/SMU
Quarknet 2001
Collide

12. Trajectory measurement
Thomas Coan/SMU
Quarknet 2001
Trajectory measurement
Charged particle
Noble “fill gas”
Electric field
Drifting ionized e-
“Drift time”  DOCA
Magnetic field curves trajectory
“curvature”  1/p

13. Thomas Coan/SMU
Quarknet 2001
CLEO Drift Chamber

14. Thomas Coan/SMU
Quarknet 2001
CLEO Drift Chamber

15. Thomas Coan/SMU
Quarknet 2001
CLEO 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

16. Scintillation Complicated phenomenon
Thomas Coan/SMU
Quarknet 2001
Scintillation
Complicated phenomenon
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

17. Sea-level muon detector
Thomas Coan/SMU
Quarknet 2001
Sea-level muon detector 
PMT
Scintillator
Discriminator
Discriminator
PMT
Scintillator
Photons enter here
Photomultiplier tube (PMT)

18. Thomas Coan/SMU
Quarknet 2001

19. Determine production height of muons
Thomas Coan/SMU
Quarknet 2001
Determine 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

20. Cerenkov Radiation Emitted by charged particles only
Thomas Coan/SMU
Quarknet 2001
Cerenkov Radiation
Emitted by charged particles only
Emitted only when particle’s speed in medium exceeds that of light’s
Pattern of light has cone-like shape:
Particle’s speed determines shape of cone
Cerenkov detectors measure particle speed
Particle momentum (mv) and speed (v)  mass

21. Cerenkov Radiation Cerenkov radiator built here at SMU for CLEO
Thomas Coan/SMU
Quarknet 2001
Cerenkov Radiation
Cerenkov radiator built here at SMU for CLEO

22. Particle “Fingerprints”
Thomas Coan/SMU
Quarknet 2001
Particle “Fingerprints”

23. Thomas Coan/SMU
Quarknet 2001
Russian Dolls
(Anna Kournakova?)

24. Thomas Coan/SMU
Quarknet 2001
“Top” event

25. How to “see” neutrinos Sudbury Neutrino Observatory (SNO)
Thomas Coan/SMU
Quarknet 2001
How to “see” neutrinos Sudbury Neutrino Observatory (SNO)

26. Cerenkov Light in Action
Thomas Coan/SMU
Quarknet 2001
Cerenkov Light in Action

27. Sudbury Neutrino Observatory
Thomas Coan/SMU
Quarknet 2001
Sudbury Neutrino Observatory

28. Summary Variety of detector types Detector combinations are the key
Thomas Coan/SMU
Quarknet 2001
Summary
Variety of detector types
Detector combinations are the key
Detector behavior is understandable