1. Cosmic Rays • 1912 discovered by Victor Hess • (after Wilson & others) • Energy range: • ~ 109 eV to > 1020 eV • 1938Pierre Auger discovered • Extensive Air Showers (EAS)

2. Sky Maps COBE Galactic Photons show the Galaxy Cosmic Rays are isotropic

3. Cosmic Ray Spectrum 32 orders of magnitude 12 orders of magnitude

4. CR Spectrum x E2.7 x E3 Features? 32 orders of magnitude Is there an end? 12 orders of magnitude

5. CR Spectrum Direct Measurements E-2.7 Air Shower Measurements 32 orders of magnitude E-3.1 12 orders of magnitude

6. The ‘knee’ at 31015 eV E2.7F E (eV)

7. A ‘second knee’ at 51017 eV ? Extra Galactic Galactic Knee 1 Knee 2 Ankle E3F and an ‘ankle’ at 31018 eV

8. CR Spectrum 2 power laws losses or coincidence E-2.7 32 orders of magnitude E-3.1 12 orders of magnitude

9. Cosmic Ray Showers One (tiny) Ultra High Energy Particle starts a shower that becomes many km2 of lower energy particles

10. AGASA 100 km2 scintillators + muon detectors Ground Arrays: Volcano Ranch Yakutsk Haverah Park SUGAR Akeno

11. Auger South 450 stations deployed! 2 sites Fluorescence 12 telescopes complete 400 working tanks

13. 2 Ultra-High Energy Cosmic Ray Observatories Fluorescence detectors Fly’s Eye

15. Fluorescence Telescope 16 x 16 PMT array 3 m diameter spherical mirror

16. 6 doublets 1 triplet above 4 x 1019 eV < 2.5 deg above 1019 eV Log E>19.6 Are UHECRs clustered? AGASA - yes?

17. HiRes - Utah HiRes-I Monocular Data, E > 1019.5 eV No clustering? HiRes-I Monocular Data, E > 1018.5 eV Upper limit of 4 doublets (90% c.l.) in HiRes-I monocular dataset. HiRes Stereo

18. UHECR come from nearby AGN? Auger Several UHECRs from Cen A? Log E>19.6 Circles = UHECR with E > 5.7 x 1019 eV, red x’s are AGN, Blue = Auger coverage, white x = Cen A

19. -resonance multi-pions High Energy Proton sees Cosmic Microwave Background as High Energy Gamma Rays! WMAP p+cmb +  p + 0  n +  + Proton Horizon GZK Cutoff Greisen ‘66, Zatsepin & Kuzmin ‘66

20. Observed High Energy Spectrum - AGASA AGASA: ~ 11 events above 1020 eV!!!

21. Observed High Energy Spectrum - Auger