1. Detection ot the Highest Energy Cosmic Rays Lecture 1 The Violent Universe Nucl Phys B (Proc Suppl) 138 (2005) 465-491 Taup Conference Proceedings 2004 James W. Cronin Les Houches, March 19,2007

3. Assume E -2.5 spectrum

4. 4

5. 5

7. Two techniques: detect shower particles on the ground detect air fluorescence produced by shower particles

8. Beyond 1500 gm/cm 2 electromagnetic particles absorbed. (Highly inclined showers)

10. 90 % of particles within Moliere radius of ≤ 100 m

12. Thin scintillators measure principally electrons and positrons. A deep water detector measures roughly the total energy flux of the shower particles at its location.

14. Note: total energy in entire shower carried by muons ≤ 10%

15. Energy deposit in 1.2 meters of water

16. At 1000 meters from core

17. 9 Signal processing can extract em/muon ratio

18. 11 Old Shower: pure muons

22. p e /A =  (  /4  )(  /r p )N e p e /A = photoelectrons/meter 2  = photocathode efficiency x mirror reflectivity ~ 0.16  = fluorescence yield ~ 4.5 UV photons/meter/particle  = 1 degree = 0.0175 r p = perpendicular distance to shower axis ~ 20 km  = attenuation ~ exp(r p /  ) ~ exp(-20/10) ~ 0.135 N e = number of charged shower particles ~ 7x10 9 for 10 19 EeV p e /A ~ 50 photoelectrons/meter 2 /degree

23. Mono 26.15 ± 0.55 km Hybrid 25.96 ± 0.02 km Calibration with central laser facility and Celeste Chi i vs time

24. 14

25. 16th16th

27. 8 S1000 is Energy parameter