Congresso del Dipartimento di Fisica Highlights in Physics 2005

1. Galaxy distribution 7-21 Mpc • Surface Array • 1600 detector station (905 deployed) • 1.5 km spacing • 3000 km2 • Duty cycle 100% • Lateral distribution of the shower front • Fluorescence Detectors • 4 FD stations (3 completed) • 6 telescopes per station • 24 Telescopes total • Duty cycle 10% • Longitudinal profile of the shower • Absolute calibration • Drum illuminator • Atmospheric monitorng • LIDAR • Central Laser Facility (CLF) Communications and GPS antennas Solar panels Electronics box DRUM White-light diffusing liner Battery box Plastic tank 12 tons of de-ionized water 3 – nine inch photomultiplier tubes 3.5 m x 3.5 m segmented mirror Rc=3.4 m, focal lenght=1.743 25 cm Corrector ring Diaphragm 2.2 m 20x22 PMT’s camera LIDAR 20x22 PMT’s camera (Ø=1.5°) Hybrid EventΘ~ 30º, ~ 8 EeV UV Filter (300-400 nm) Mendoza, Argentina (construction underway) CLF Colorado, USA (in planning) Fitted Electromagnetic Shower Tanks Pixels Time μ sec from Fly's Eye 1985 Angle Χ in the shower-detector plane Congresso del Dipartimento di Fisica Highlights in Physics 2005 11–14 October 2005, Dipartimento di Fisica, Università di Milano The Pierre Auger observatory: a hybrid detector looking for the ultra high energy cosmic rays C. De Donato*, F. Sánchez*,†, D.V. Camin*,† and V.Grassi*,† * Dipartimento di Fisica, Università di Milano † INFN – Sezione di Milano The Pierre Auger Observatory has been conceived to study the cosmic ray spectrum in the Ultra High Energy region (above 1018 eV). Although the existence of such energetic particles is now beyond doubt, their nature has not been explained yet. To solve this enigma the esperiment will measure the properties of the highest energy cosmic rays with unprecedent statistical precision combinig two traditional and independent techniques in an unique and innovative hybrid detector. Science Objectives • Cosmic ray spectrum above 1019 eV • Shape of the spectrum in the region of the GZK feature • Arrival direction distribution • Search for departure from isotropy – point sources • Composition • Light or heavy nuclei, photons, neutrinos, exotics(?) Design Features • High statistics :aperture >7000 km2 sr above 1019eV in each hemisphere • Full sky coverage with uniform exposure • Hybrid configuration – surface array (water-Cherenkov tanks) with fluorescence detector coverage: • High resolution in energy and geometric reconstruction • Complementary set of mass sensitive shower parameters • Crossed calibration through two different measurement techniques • Max hybrid efficiency above 1019eV for zenith angle <60° • 100% monocular detection • 60% stereo detection Aligned tanks 1.5 km First Data Set • Collection period – 1 January 2004 to 5 June 2005 • Zenith angles - 0 - 60º • Total acceptance – 1750 km2 sr yr (~ AGASA) • Surface array events (after quality cuts) • Current rate - 18,000 / month • Total -~180,000 • Hybrid events (after quality cuts) • Current rate – 1800 / month • Total ~ 18000 Participating Countries (*Associate) Argentina Czech Republic Mexico Spain Australia France Netherlands United Kingdom Bolivia* Germany Poland USA Brazil Italy Slovenia Vietnam* Italian groups: Catania, L’Aquila, Lecce, Milano, Napoli, Roma, Torino 63 Institutions, 369 Collaborators