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

3. CLEO Thomas Coan/SMUQuarknet 2001 Particle Properties lifetime mass electric charge ”spin”

4. CLEO Thomas Coan/SMUQuarknet 2001 General Idea of Colliding Particle Experiments Collide probe particles with target Detect particles from collision Interpret results

5. CLEO Thomas Coan/SMUQuarknet 2001 Early Particle Physics Experiment Interpretation: Set-up: Ernest Rutherford 1909

6. CLEO Thomas Coan/SMUQuarknet 2001 How do we “shoot” probe particles? * Acquire some probe particles * Accelerate the probe particles * Steer and aim the probe particles Final speed  c

7. CLEO Thomas Coan/SMUQuarknet 2001 Accelerator Types Circular

8. CLEO Thomas Coan/SMUQuarknet 2001 Accelerator Types Linear

9. CLEO Thomas Coan/SMUQuarknet 2001 Target Types Colliding beam Fixed target

10. CLEO Thomas Coan/SMUQuarknet 2001 Wave Nature of Particles Electron diffraction: particle as wave Waves interfere:

11. CLEO Thomas Coan/SMUQuarknet 2001 Why use higher and higher energies? = h/p  The more energetic the probe, the finer the accessible detail

12. CLEO Thomas Coan/SMUQuarknet 2001 Collide

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

14. CLEO Thomas Coan/SMUQuarknet 2001 CLEO Drift Chamber

15. CLEO Thomas Coan/SMUQuarknet 2001 CLEO Drift Chamber

16. CLEO Thomas Coan/SMUQuarknet 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

17. CLEO Thomas Coan/SMUQuarknet 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

18. CLEO Thomas Coan/SMUQuarknet 2001 Sea-level muon detector PMT Scintillator PMT Scintillator Photomultiplier tube (PMT) Photons enter here  Discriminator

19. CLEO Thomas Coan/SMUQuarknet 2001

20. CLEO Thomas Coan/SMUQuarknet 2001 Determine production height of muons 1 2 3 1 2 3 Earth Atmosphere Sea level  flux depends on pathlength from production point Changing telescope angle changes pathlength Flux change  production height  h hh

21. CLEO Thomas Coan/SMUQuarknet 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

22. CLEO Thomas Coan/SMUQuarknet 2001 Cerenkov Radiation Cerenkov radiator built here at SMU for CLEO

23. CLEO Thomas Coan/SMUQuarknet 2001 Particle “Fingerprints”

24. CLEO Thomas Coan/SMUQuarknet 2001 Russian Dolls

25. CLEO Thomas Coan/SMUQuarknet 2001 “Top” event

26. CLEO Thomas Coan/SMUQuarknet 2001 How to “see” neutrinos Sudbury Neutrino Observatory (SNO)

27. CLEO Thomas Coan/SMUQuarknet 2001 Cerenkov Light in Action

28. CLEO Thomas Coan/SMUQuarknet 2001 Sudbury Neutrino Observatory

29. CLEO Thomas Coan/SMUQuarknet 2001 Summary Variety of detector types Detector combinations are the key Detector behavior is understandable