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Status, Performance and Perspectives of the Auger Observatory

Status, Performance and Perspectives of the Auger Observatory. Stefano Argirò 1 for the Auger Collaboration. University of Torino, Italy, and INFN. 1. Physics case The Auger Observatory Performance Preliminary Analysis Conclusions. EPS 2003. Physics Case.

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Status, Performance and Perspectives of the Auger Observatory

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  1. Status, Performance and Perspectives of the Auger Observatory Stefano Argirò1 for the Auger Collaboration University of Torino, Italy, and INFN 1 Physics case The Auger Observatory Performance Preliminary Analysis Conclusions EPS2003

  2. Physics Case Air Showers generated by primaries with E>1020 eV exist 20 events observed in the past 40 yr Standard Astrophysical models cannot easily account for such E Astrophysical sources must be near GZK cutoffat 50 Mpc for E>1020 eV Near sources should be identified by point source astronomy High magnetic rigidity of the primaries Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  3. The UHECR Problem • What is the source of CR of such energies ? • Are sources uniformly distributed ? • What is the composition of the primaries ? • Is GZK violated ? The experimental situation is rather controversial: • Difficulty of the measurements • Low statistics 1 particle/yr/km2 E>1019 0.01 particle/yr/km2 E>1020 The Pierre Auger Observatory responds with: • Precision Measurements Hybrid Detector • Large area 3000 + 3000 km2 • Full sky coverage (Harmonic Analysis) • Sensitivity to -induced showers ! Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  4. Physics (oversimplified) scenarios Experimental evidence Meaning Distribution of arrival directions Anisotropy – point sources Astroph objects Isotropy decay of superheavy relics or other new physics Uniformly distributed Astroph sources but depending on composition & magnetic fields Composition: features of the spectrum new physics gamma NS, very near sources heavy goto GZK proton GZK near Astroph sources new physics Violated Conserved far Astroph sources

  5. 1000000 1,000 *year) EUSO 100000 ) str eV Auger 20 (N+S) 100 10000 HiRes No. of Events (E > 10 Integrated Aperture (km^2* AGASA 10 1000 Fly’s Eye 1 100 1985 1990 1995 2000 2005 2010 2015 2020 Year Integrated exposure Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  6. Northern site Millard County Utah, USA Auger Sites Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  7. The Pierre Auger Observatory Southern Site 1600 Water Cerenkov Detectors, 1.5 km spacing 24 Fluorescence Telescopes + extensive atmospheric monitoring 3000 km2 of instrumented area Lat : -35, Long: -69, Elevation: 1430 m Malargue Population : 15000 Northern Site: configuration to be detailed Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  8. EngineeringArray PreProductionArray

  9. The Hybrid Detector Concept Surface Array Simple and reliable detectors 100% duty cycle Energy Determination relies on simulation Fluorescence Detector Quasi calorimetric energy measurement Tracks directly shower developement 10-15 % duty cycle Sistematics from atmospheric transparency Combination Cross Calibration Better control of systematics Superior Angular resolution Independent measurement of Energy Composition: /e , Xmax Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  10. The Surface Detector Commantenna electronic box 40 Mhz sampling 12+12 bit FADC Local Trigger Solar panel GPSantenna Three 8” PM Tubes White light diffusing liner 12 m3 of de-ionized water Plastic tank Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  11. SD Calibration Detect presence of hump from atmospheric muons with a special trigger. Scale to Vertical Equivalent Muon measured on a sample tank equipped with scintillators Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  12. Fluorescence Detector 30° x 30 ° fov Schmidt optics 440 pixels 1.5 ° Ø pixel 12 bit FADC 10 Mhz fs < 4 g/cm2 Digital trigger Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  13. Aperture

  14. Mirror

  15. Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  16. FDCalibration Calibrated light source Diffusely reflective drum N Photons at diaphragm  FADC counts Absolute: End to End Calibration The Drum device installed at the aperture uniformly illuminates the camera with light from a calibrated source (1/month) Mirror Camera Relative: UV LED + optical fibers (1/night) • Alternative techniques for cross checks • Scattered light from laser beam • Statistical All agreed within 10% for the EA Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  17. Atmospheric Monitoring Crucial for an accurate energy measurement Rayleigh (molecular) scattering and Mie (aerosol) scattering are the physical process to be accounted for. Rayleigh is easy to measure, but Mie is not. • Wheather stations • Horizontal Attenuation Monitors • Aerosol Phase Function Monitors • Cloud Monitors • Balloon launches • Lidar systems Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  18. Status Engineering Array Phase completed 35 Surface Detector Tanks 2 Fluorescence Telescopes Successful Detection of Hybrid events Production phase started 100 tanks positioned with production electronics 200 by end of September 400 by Jan 2004 1600 by Jul 2005 2 eye buildings completed 2 telescopes commissioned with production electronics 3+2 by end 2003 (stereo detection by end of 2003) 6+6 by first quarter 2004 Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  19. Performance SD :  6000 triggers since Dec 2001  600 shower candidates E>1018  120 with more than 5 tanks FD:  1000 triggers  500 real showers  50 have quality such that energy can be roughly estimated many laser shots for detector studies 77 hybrid events Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  20. Geometrical Reconstruction SD xcore, ycore from barycenter of triggered tanks weighted by signal ,  from arrival times ,  from minimization of core 100m , 1 Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  21. EM shower Shower core hard muons Shower front Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  22. t0 SDP Shower Axis Shower Front Rp 0 i impact point FD hit station tSD FD Geometrical Reconstruction Two Steps: • Shower Detector Plane • Axis SDP The Plane that minimizes the sum of the square angular differences from the direction of the hit pixels Nsdp  0.3 Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  23. FD Mono:Axis The Time Fit Tests with laser shots thrown at known direction (aiming at a star) core  800m ,  1 FD stereo: intersection of SDP

  24. Hybrid Reconstruction Problem of the time fit: 3 parameter fit from an almost linear function between time and position accuracy depends on geometry (toward/outward) Additional constraint from time of stations Hybrid resolution core  30 m , 0.3 Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  25. Analysis Example •  = 54.3 ± 0.5  • = -77.8 ± 0.8 n = 11 E = 2035 EeV #184599,Friday April 2002. Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  26. Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  27. Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  28. Lateral Distribution Energy from S1000 10 events/curve Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  29. Signal Fluctuations Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  30. Longitudinal Profile Received light at aperture, emitted between X and X+X: Atmospheric Transmission Trayleigh T aerosol Fluorescence yield function Fy from lab measurements Cerenkov contamination subtracted by an iterative procedure e-m energy estimation: From Gaisser-Hillas fit to profile Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  31. run 505 ev 544 theta 55.6 ° phi 122.7 ° X 9.8 Km Y 8.8 Km R 13.1 km Eem  1.3 1019 eV Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  32. FD Event Display Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  33. run 531 ev 68 theta 48.1° phi -135.6 ° X 4.4 Km Y 19.0 Km R 19.5 km Eem  3.3 1019 eV Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  34. Conclusions The Engineering Array proved that: The Detector design is sound The technical difficulties are sorted out We are able to calibrate and operate the detectors smoothly We are able to take consistent data and perform a thorough and consistent analysis The Challenge: Timely completion of the Southern Observatory Startup of Northern Observatory Stefano Argirò, “Status ... of the Pierre Auger Observatory”

  35. Tevatron LHC

  36. D. Bergman, ICHEP 2002 Stefano Argirò, “Status ... of the Pierre Auger Observatory”

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