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AGASA Results Masahiro Teshima Max-Planck-Institut fr Physik, Mnchen, Germany for AGASA collaboration Slide 2 AGASA Cosmic Ray Energy Spectrum P 3K GZK mechanism AGASA Energy Spectrum Super GZK part. ~1/km 2 century Slide 3 AGASA AGASA Akeno Giant Air Shower Array 111 Electron Det. 27 Muon Det. 0 4km Slide 4 AGASA Exposures of various experiments Auger Slide 5 AGASA Detector Calibration in AGASA experiment Detector Gain by muons in each run Cable delay (optic fiber cable) Gain as a function of time (11years data) Accuracy of 100ps by measuring the round trip time in each run Detector Position Survey from Airplane 0.1m, 0.3m Linearity as a function of time (11years data) Slide 6 AGASA Linearity check after dismantling detectors in 2004 Feb At Akeno Observatory Central building in 2004 Jan Slide 7 AGASA Detector Simulation (GEANT) Detector Housing (Fe 0.4mm) Detector Box (Fe 1.6mm) Scintillator (50mm) Earth (Backscattering) vertical = 60deg Detector Response Energy spectra of shower particles Slide 8 AGASA Energy Determination Local density at 600m Good energy estimator by M.Hillas Good energy estimator by M.Hillas E=2.13x10 20 eV Slide 9 AGASA The Highest Energy Event 2.5 x10 20 eV on 10 May 2001 Slide 10 AGASA Attenuation curve S(600) vs N ch 10 18 eV Proton Atmospheric depth Slide 11 AGASA S600 Attenuation curve Atmospheric depth 20.0 19.5 19.0 18.5 18.0 Slide 12 AGASA S600 Intrinsic fluctuation Proton Iron Slide 13 AGASA The Conversion from S600 to Energy Muon/Neutrino Ele. Mag Slide 14 AGASA Energy Resolution 30% 25% mainly due to measurement errors (particle density measurement and core location determination) not due to shower fluctuation Slide 15 AGASA Major Systematics in AGASA astro-ph/0209422 Detector Detector Absolute gain 0.7% Detector Absolute gain 0.7% Detector Linearity 7% Detector Linearity 7% Detector response(box, housing) 5% Detector response(box, housing) 5% Energy Estimator S(600) Interaction model, P/Fe, Height15% Interaction model, P/Fe, Height15% Air shower phenomenology Lateral distribution function 7% Lateral distribution function 7% S(600) attenuation 5% S(600) attenuation 5% Shower front structure 5% Shower front structure 5% Delayed particle(neutron) 5% Delayed particle(neutron) 5% Total 18% Slide 16 AGASA Energy Spectrum by AGASA ( AGASA Arrival Direction Distribution >4x10 19 eV zenith angle 4x10 19 eV zenith angle AGASA Space Angle Distribution of Arbitrary two events >4x10 19 eV Normalized sigma by Li & Ma 3.2 sigma Slide 28 AGASA Arrival Direction Distribution >10 19 eV Slide 29 AGASA Space Angle Distribution Log E>19.6 Log E>19.4 Log E>19.2Log E>19.0 Slide 30 AGASA (1000) distribution Slide 31 AGASASummary Super GZK particles exist Preliminary study with recent CORSIKA Preliminary study with recent CORSIKA If recent CORSIKA describes showers correctly, AGASA energy scale will shift down by ~10% at 10 19 eV and by ~15% at 10 20 eV on average by ~10% at 10 19 eV and by ~15% at 10 20 eV on average Spectrum seems to be more featureless (in preliminary study) ?? Discrepancy between AGASA and HiRes becomes less significant Small scale anisotropy of UHECR The arrival direction of UHECRs is uniform in large scale The arrival direction of UHECRs is uniform in large scale But AGASA data shows clusters, 1 triplets and 6 doublets granularity But AGASA data shows clusters, 1 triplets and 6 doublets granularity Source density ~10 -5 /Mpc 3 ~ density of AGNs Source density ~10 -5 /Mpc 3 ~ density of AGNs Re-analysis is on-going with new shower front structure (but very slow) Re-analysis is on-going with new shower front structure (but very slow) Chemical composition at 10 19 eV Consistent with light component (P) Consistent with light component (P) No gamma ray dominance, /all