Detection ot the Highest Energy Cosmic Rays Lecture 1 The Violent Universe Nucl Phys B (Proc Suppl)...
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Transcript of Detection ot the Highest Energy Cosmic Rays Lecture 1 The Violent Universe Nucl Phys B (Proc Suppl)...
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
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/cm2
electromagnetic particlesabsorbed. (Highly inclined showers)
90 % of particleswithin Moliereradius of ≤ 100 m
Thin scintillators measure principally electrons andpositrons.
A deep water detector measures roughly the total energy flux of the shower particles at its location.
Note: total energy inentire showercarried by muons ≤ 10%
Energy deposit in1.2 meters of water
At 1000 meters from core
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Signal processing can extract em/muon ratio
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Old Shower: pure muons
pe /A = (/4)(/rp)Ne
pe/A = photoelectrons/meter2
= photocathode efficiency x mirror reflectivity ~ 0.16
= fluorescence yield ~ 4.5 UV photons/meter/particle
= 1 degree = 0.0175
rp = perpendicular distance to shower axis ~ 20 km
= attenuation ~ exp(rp/) ~ exp(-20/10) ~ 0.135
Ne = number of charged shower particles ~ 7x109 for 1019 EeV
pe/A ~ 50 photoelectrons/meter2/degree
Mono 26.15 ± 0.55 km
Hybrid 25.96 ± 0.02 kmCalibration with central laser facility and Celeste
Chii vs time
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16th
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S1000 isEnergy parameter