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Pierre Auger Observatory

Pierre Auger Observatory. Outline. Cosmic Rays Pierre Auger Observatory Description/Status Enhancements Future Auger Results Auger @ LIP Detector Simulation Measurements Phenomenology Conclusions. M. Pato, P. Assis, P. Brogueira, P. Abreu , P. Gonçalves, B. Tomé, J. Romão,

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Pierre Auger Observatory

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  1. Pierre Auger Observatory

  2. Outline • Cosmic Rays • Pierre Auger Observatory • Description/Status • Enhancements • Future • Auger Results • Auger @ LIP • Detector Simulation • Measurements • Phenomenology • Conclusions M. Pato, P. Assis, P. Brogueira, P. Abreu , P. Gonçalves, B. Tomé, J. Romão, R. Conceição, M. Pimenta, S. Andringa, E. Santos, M. C. Espírito Santo, J. Dias de Deus, J. G. Milhano

  3. Ultra-High Energy Cosmic Rays • Cosmic rays with E > 1020 eV arrive on Earth at the rate of 1 particle per km2 per century • Their composition and their sources are unknown • Create a shower of particles when they enter the atmosphere • Hadronic • Electromagnetic • Can be detected • Ground Arrays • Fluorescence Detector • Moonless nights

  4. Pierre Auger Observatory • The Auger Observatory is a "hybrid detector," employing two independent methods to detect and study high-energy cosmic rays: • Surface detector (SD) • 3000 km2 in the Pampa Argentina • 1600 pure water tanks • 1.5 km spacing • Flourescence Detector (FD) • 4 “eyes” • 6 telescopes in each viewing 30º x 30º • 4 weather stations (with LIDARs) • 2 Laser Facilities FD SD 20 May 2007 E ~ 1019 eV

  5. Event Reconstruction Surface Detector Fluorescence Detector • Tank hit time gives shower direction • Energy is obtained using Nch( distance to the shower core ) • Evolution in camera gives the shower geometry • Energy is calculated by integrating a universal longitudinal profile

  6. Hybrid Technique • Better reconstruction geometry • Higher Xmax resolution • Better energy reconstruction • Calibration of SD with FD • Reduce systematics • Good correlation between SD and FD SD FD

  7. Auger Enhancements AMIGA HEAT Extend studies to lower energies ~ 1017 eV • Auger Muons and Infill for the Ground Array • Study muon component of showers • Good variable to check hadronic models • – Hexagon (7 x 60 m2) • 2 – Infill array 433m • 3 – Existing tank array 1500m • 4 – Infill array 750m • High Elevation Auger Telescopes • 3 “standard” Auger telescopes tilted to cover 30 - 60° elevation

  8. Future Auger North Auger South Extension • Construction 2009-2012 ? • Total area: 20 000 km2 • About 7 x Auger South extension • 4032 surface detectors • 3 FD eyes • Expansion possibilities for Auger South If a non-compact configuration is acceptable • 60 000 km2 ?? • Many possible Upgrades • Radio Antenna Array • … 1 Linsley = 1 L = 1 km2 sr yr

  9. Auger Results Energy Spectrum Anisotropies Xmax

  10. Energy Spectrum • GZK cut-off • Interaction with CMB photons degrades energy • Ankle • Transition from galactic to extra-galactic sources?

  11. Anisotropies Search for Sources ( E > 57 EeV ) positions of (318 visible+164invisible) AGNs at z < 0.018 (D< 75 MPc) 19 out of 27 events are within 3.1º of an AGN !! ( The probability of having an isotropic distributions is 10-5 )

  12. Evidence for Proton Primary? • Angular aperture • α = 3.1 • Distance • z < 0.018 → D < 75 MPc • Energy • E > 57 EeV Low E High Z High E Low Z The angular aperture suggests that the particle is a proton!

  13. Xmax – Primary Composition • Iron showers develop faster than proton • Slope depends strongly on the interaction models • Auger data indicates heavier composition at high energy!!!!! Particle Physics?!...

  14. LIP @ Auger Particle Physics @ Cosmic Rays Good understand of the detector Geant 4 Simulation of the FD Simulation studies for AMIGA New variables from data 3D Analysis Čerenkov Phenomenological Models

  15. FD Simulation with Geant 4 Going into detail...

  16. Geant 4 Simulation Mirror curvature from database!! • Good overall agreement with official simulation • Small differences with some more realistic settings • Good tool to find systematics!!

  17. New possibilities…

  18. Simulation studies for AMIGA • Muon selection effieciencies of 80 to 90% • About 10% of multihits

  19. 3D Reconstruction Method • Currently for FD the shower is being treated as a 1D object but it’s an 3D object • It is possible to get information about the “width” of the shower taking the arrival time of photons at the detector into account • It uses time as a 3rd dimension Adding Time

  20. 3D Reconstruction Method Longitudinal Profile Lateral Profile Simulation • This method obtains a good agreement with the simulation • Longitudinal Profile • Lateral Profile • Low statistics Ratio Expected / Observed

  21. 3D Reconstruction Method Longitudinal Profile Lateral Profile Experimental Data • 6 Months of data • Longitudinal Profile shows a good agreement • Lateral Profile shows a clear disagreement • Data seems wider • Detector? • Physics?? Ratio Expected / Observed

  22. 3D Simulation • Currently: • Čerenkov and fluorescence photons are produced from longitudinal profiles (1D) • All photons are propagated to the lens and then spread transversally • A 3D Reconstruction needs a 3D Simulation! Auger Simulation and Reconstruction Software (Offline) with some modifications

  23. 3D Simulation Already a first shower… Shower at 4980 m from Los Leones – seen in Eye 1

  24. a Shower axis c0 FD Čerenkov • Shower produce intense colimated beam • Events with a large fraction of Čerenkov light are interesting because they allow us to: • See further away • Improve horizontal ν search • Study Čerenkov properties • A(α) – Lateral Distribution Function of Čerenkov

  25. Extensive Air Shower (EAS) Physics Exploring High Energy Hadronic Models… • Phenomenological Approach • Extrapolate from accelerator energies to several orders of magnitude above Models New models and possible high energy effects…

  26. String Percolation • As energy increases the number of sea strings increases • Strings overlap and fuse creating more energetic strings with higher length in rapidity • Create faster particles • Change the type of the leading particle • In EAS: • Change number of muons • Change the Xmax But how important are valence quarks??

  27. Net-Baryon ( Simple Model ) • Net-Baryon is • Two step-scenario Model • String Formation • Valence quarks • Energy obtained from PDFs • Parameter Q2 (√s) • String Fragmentation • String decays into a meson and a baryon • Kinematic Constraints

  28. Net-Baryon Results • Usual Models have problems explaining the data • Effective Q2 obtained from fit to data • Evolution with energy is a consequence of QCD evolution of the PDFs and the kinematic constraints in the string fragmentation • Simple model can reproduce Net-Baryon main features • Our model shows that the role of the Net-Baryon is not negligible

  29. Conclusions • Auger opens new windows in: • Astrophysics • Particle Physics • The LIP group has an active and enthusiastic participation!!

  30. A little bonus…

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