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AGASA Results Max-Planck-Institut für Physik, München, Germany Masahiro Teshima for AGASA collaboration at 3 rd Int. Workshop on UHECR, Univ. Leeds

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Cosmic Ray Energy Spectrum P γ3K Δ Ｎ π GZK mechanism AGASA Energy Spectrum Super GZK part. ~1/km 2 century

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AGASA Akeno Giant Air Shower Array 111 Electron Det. 27 Muon Det. 0 4km

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Exposure in ICRC2003 Auger

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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 Δ Ｘ， Δ Ｙ＝ 0.1m, Δ Ｚ＝ 0.3m Linearity as a function of time (11years data)

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Detector Simulation ( GEANT) Detector Housing (Fe 0.4mm) Detector Box (Fe 1.6mm) Scintillator (50mm) Earth (Backscattering) vertical θ = 60deg Detector Response Energy spectra of shower particles

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Linearity check

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Energy Determination Local density at 600m Good energy estimator by M.Hillas E=2.13x10 20 eV, E >= 1.6x10 20 eV

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Third Highest event 97/03/30 150EeV 40 detecters were hit

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The Highest Energy Event (2.46 x10 20 eV, E>1.6x10 20 eV) on 10 May 2001

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Attenuation curve S(600) vs N ch 10 18 eV Proton Atmospheric depth

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S600 Attenuation curve 0-45° 0-60° Atmospheric depth 20.0 19.5 19.0 18.5 18.0

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S600 Intrinsic fluctuation for proton and iron Proton Iron

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The Conversion from S600 to Energy Muon/Neutrino Ele. Mag

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Major Systematics in AGASA astro-ph/0209422 Detector Detector Absolute gain± 0.7% Detector Linearity± 7% Detector response(box, housing)± 5% Energy Estimator S(600) Interaction model, P/Fe, Height±15% Air shower phenomenology Lateral distribution function± 7% S(600) attenuation± 5% Shower front structure ± 5% Delayed particle(neutron) ± 5% Total ± 18%

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Energy Resolution 30% 25% mainly due to measurement errors (particle density measurement and core location determination) not due to shower fluctuation

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Energy Spectrum by AGASA (θ<45) 11 obs. / 1.8 exp. 4.2σ 5.1 x 10 16 m 2 s sr

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The Energy spectrum by AGASA Red: well inside the array (Cut the event near the boundary of array)

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AGASA vs HiRes (astro-ph) See new paper: Energy determination in AGASA (astro-ph/0209422)

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Recent spectra (AGASA vs. HiRes@Tsukuba ICRC) ~2.5 sigma discrepancy between AGASA & HiRes Energy scale difference by 25% vs. HiRes-stereo vs. HiRes-I vs. HiRes-II

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Arrival Direction Distribution >4x10 19 eV zenith angle <50deg. Isotropic in large scale Extra-Galactic But, Clusters in small scale ( Δθ< 2.5deg) 1triplet and 6 doublets (2.0 doublets are expected from random) One doublet triplet(>3.9x10 19 eV) and a new doublet(<2.6deg)

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Space Angle Distribution of Arbitrary two events >4x10 19 eV Normalized sigma by Li & Ma 3.2 sigma

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Arrival Direction Distribution >10 19 eV

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Space Angle Distribution Log E>19.6 Log E>19.4 Log E>19.2Log E>19.0

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Energy spectrum of Cluster events ∝ E -1.8+-0.3 Cluster Component

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ρ μ (1000) distribution

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Akeno 1km 2 (A1): Hayashida et al. ’95 Haverah Park (HP): Ave et al. ’03 Volcano Ranch (VR): Dova et al. (ICRC ‘03) HiRes (HiRes): Archbold et al. (ICRC ‘03) A1: PRELIMINARY 10 17.5 eV – 10 19 eV (Akeno 1km 2 array) Gradual lightening Above 10 19 eV (AGASA) Fe frac.: <40% (@90% CL) Chemical composition study by muons (p+Fe composition assumption; AIRES+QGSJET) (PRELIMINARY)

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Limits on gamma-ray fraction Gamma-ray fraction upper limits (@90%CL) 34% (>10 19 eV) ( /p<0.45) 56% (>10 19.5 eV) ( /p<1.27) to observed events Topological defects (Sigl et al. ‘01) (M x =10 16 [eV]; flux normalised@10 20 eV ) Z-burst model(Sigl et al. ‘01) (Flux normalised@10 20 eV) SHDM-model (Berezinski et al. ‘98) (Mx=10 14 [eV]; flux normalised@10 19 eV ) Assuming 2-comp. (p+gamma-ray) primaries

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Summary Super GZK particles exist AGASA HiRes difference is small, problem; FLUX Origin of UHECR (Possible scenario) Fe Primary – most economical scenario – but not likely Decay of Heavy Relics in our Halo (WIMPZILLA) Violation of Special Relativity AGNs, GRBs or other astronomical objects Over density? Small scale anisotropy of UHECR AGASA data shows clusters, 1 triplets 6 doublets Source density ~10 -5 /Mpc 3 ~ density of AGNs Chemical composition at 10 19 eV Consistent with light component (P) No gamma ray dominance, γ/all <34%

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New Projects for UHECRs Golden Time for UHECRs

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