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The Pierre Auger Observatory

The Pierre Auger Observatory. Hunting the Highest Energy Cosmic Rays I – High Energy Cosmic Rays and Extensive Air Showers. Discovery of Cosmic Rays. Altitude variation of ionisation detected by Hess and Kohlhoster and Pfotzer. The Cosmic Ray Spectrum. Outstanding Issues.

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The Pierre Auger Observatory

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  1. The Pierre Auger Observatory Hunting the Highest Energy Cosmic Rays I – High Energy Cosmic Rays and Extensive Air Showers E.Menichetti - Villa Gualino, March 2007

  2. Discovery of Cosmic Rays Altitude variation of ionisation detected by Hess and Kohlhoster and Pfotzer E.Menichetti - Villa Gualino, March 2007

  3. The Cosmic Ray Spectrum E.Menichetti - Villa Gualino, March 2007

  4. Outstanding Issues Acceleration Mechanism GZK Composition Point Sources E.Menichetti - Villa Gualino, March 2007

  5. The Magnetic Mirror Energy exchange Drift ↔ Revolution Inhomogeneous B field Spiral trajectories around field lines High gradient regions acting like walls E.Menichetti - Villa Gualino, March 2007

  6. Fermi Mechanism - 2nd Order Scattering by B-field Stochastic process: DE2E Expect: Slow, inefficient E.Menichetti - Villa Gualino, March 2007

  7. Fermi Mechanism - 1st Order As before, scattering by B -field irregularities Momentum gain: Expect: fast, efficient Speed=U1 >Speed=U2 Shock compression ratio E.Menichetti - Villa Gualino, March 2007

  8. Maximum Energy Simple estimate of max. energy (Hillas): b: plasma speed B: mag field L: source size E.Menichetti - Villa Gualino, March 2007

  9. Spectral Index, Time Constant Power law spectrum Fermi 2nd order: tacc>108 yr! KO Fermi 1st order: tacc~1 month! OK E.Menichetti - Villa Gualino, March 2007

  10. Compact sources Just meaning: non electromagnetic acceleration Various mechanisms proposed: Black hole accretion disks Gamma ray bursts Topological defects (monopoles, cosmic strings, ..) UHE n’s from decays of high mass particles E.Menichetti - Villa Gualino, March 2007

  11. Cosmic Microwave Background Penzias, Wilson & the Antenna The CMB spectrum (by FIRAS) E.Menichetti - Villa Gualino, March 2007

  12. CMB Photons Peak energy  kBT= 0.6 meV Density  400 cm-3 Possible CR interactions: ,A ,A E.Menichetti - Villa Gualino, March 2007

  13. G(reisen),Z(atepsin),K(uz’min) (G, Z&K - 1965) The moral: CR’s above threshold bound to lose energy E.Menichetti - Villa Gualino, March 2007

  14. The GZK Cutoff So UHECR’s just can’t propagate beyond, say, 50 Mpc! Then we should find a suitable source just ‘round the corner’. But where? E.Menichetti - Villa Gualino, March 2007

  15. The High End of the CR spectrum ~ x 2 effect ~ 2-3 s issue.. E.Menichetti - Villa Gualino, March 2007

  16. Composition Issues Spectrum Depth of Shower Maximum in Air vs. E Galactic? Extra-Galactic? E.Menichetti - Villa Gualino, March 2007

  17. More on Composition Proton/Iron Discrimination tied to Intra/Extra-Galactic origin E.Menichetti - Villa Gualino, March 2007

  18. Opening a New Window? Effect of Extra-Galactic Magnetic Field on CR trajectories –Simulation E = 1018 eV E = 1020 eV Clearly, around 1020 eV a new astronomy is feasible… …if Cosmic Rays of that energy are actually observed E.Menichetti - Villa Gualino, March 2007

  19. The Known Matter (< 21 Mpc) E.Menichetti - Villa Gualino, March 2007

  20. Anisotropies, Point Sources? AGASA Controversial results… Issues at stake: Detection Technique Angular Resolution Statistics! > 6 Clusters observed HIRES No cluster E.Menichetti - Villa Gualino, March 2007 E.Menichetti – SIF 2006

  21. Cosmic Rays Detection Direct detection - Up to 1014 eV Main limitation: Flux Usually performed by balloons, satellites, … Extensive Air Showers – Above 1014 eV Primary particle interaction in upper atmosphere Developing shower detected by different techniques E.Menichetti - Villa Gualino, March 2007

  22. EAS Development • Primary interaction in the high atmosphere • Hadronic Shower • Charged mesons Muons • Neutral mesons Photons • Muon component • + • EM Shower ~10 km E.Menichetti - Villa Gualino, March 2007

  23. EAS – Cross Section E.Menichetti - Villa Gualino, March 2007

  24. EAS – EAS development Next ~6 slides from R.Engel’s simulations See for example: R.Engel EAS Lectures given at ISAPP 2005 Summer School http://www.isapp2005.to.infn.it/ E.Menichetti - Villa Gualino, March 2007

  25. EAS-I E.Menichetti - Villa Gualino, March 2007

  26. EAS-II E.Menichetti - Villa Gualino, March 2007

  27. EAS-III E.Menichetti - Villa Gualino, March 2007

  28. EAS-IV E.Menichetti - Villa Gualino, March 2007

  29. EAS-V E.Menichetti - Villa Gualino, March 2007

  30. EAS - Profiles Longitudinal Lateral E.Menichetti - Villa Gualino, March 2007

  31. EAS - Electron Lateral Distribution E.Menichetti - Villa Gualino, March 2007

  32. EAS - Muons vs Electrons E.Menichetti - Villa Gualino, March 2007

  33. EAS- Elongation Rate E.Menichetti - Villa Gualino, March 2007

  34. EAS Detectors Long history, dating back to the ’60s Volcano Ranch (USA) – Sampling Haverah Park (UK) – Sampling SUGAR (Australia) - Sampling Yakutsk (Russia) - Sampling Fly’s Eye (USA) – Fluorescence AGASA HiRes E.Menichetti - Villa Gualino, March 2007

  35. AGASA Akeno Giant Air Shower Array 111 scintillators + 27 muon det. Akeno, Japan 11 Super-GZK events Small Scale Clustering Constraints on Composition:  protons at UHEs. (“Classical” analysis based on Ne vs Nm) E.Menichetti - Villa Gualino, March 2007

  36. HiResHigh Resolution Fly’s Eye Pioneers of FluorescenceTechnique Air fluorescence detectors HiRes 1 - 21 mirrors HiRes 2 - 42 mirrors Dugway, Utah, USA No Super-GZK flux No Small Scale Clustering Composition Change E.Menichetti - Villa Gualino, March 2007

  37. EAS – The Movie E.Menichetti - Villa Gualino, March 2007

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