Detection ot the Highest Energy Cosmic Rays Lecture 1 The Violent Universe Nucl Phys B (Proc Suppl) 138 (2005) Taup Conference Proceedings 2004 James W. Cronin Les Houches, March 19,2007
Assume E -2.5 spectrum
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Two techniques: detect shower particles on the ground detect air fluorescence produced by shower particles
Beyond 1500 gm/cm 2 electromagnetic particles absorbed. (Highly inclined showers)
90 % of particles within Moliere radius of ≤ 100 m
Thin scintillators measure principally electrons and positrons. A deep water detector measures roughly the total energy flux of the shower particles at its location.
Note: total energy in entire shower carried by muons ≤ 10%
Energy deposit in 1.2 meters of water
At 1000 meters from core
9 Signal processing can extract em/muon ratio
11 Old Shower: pure muons
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 = r p = perpendicular distance to shower axis ~ 20 km = attenuation ~ exp(r p / ) ~ exp(-20/10) ~ N e = number of charged shower particles ~ 7x10 9 for EeV p e /A ~ 50 photoelectrons/meter 2 /degree
Mono ± 0.55 km Hybrid ± 0.02 km Calibration with central laser facility and Celeste Chi i vs time
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16th16th
8 S1000 is Energy parameter