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AGASA Results

AGASA Results. Max-Planck-Institut f ü r Physik, M ü nchen, Germany Masahiro Teshima for AGASA collaboration at 3 rd Int. Workshop on UHECR, Univ. Leeds. GZK mechanism. Ｎ. P. Δ. Super GZK part. ~1/km 2 century. π. γ3K. Cosmic Ray Energy Spectrum. AGASA Energy Spectrum.

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AGASA Results

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

  2. GZK mechanism Ｎ P Δ Super GZK part. ~1/km2 century π γ3K Cosmic Ray Energy Spectrum AGASA Energy Spectrum

  3. AGASAAkeno Giant Air Shower Array 111 Electron Det. 27 Muon Det. 0 4km

  4. Auger Exposure in ICRC2003

  5. Detector Calibration in AGASA experiment Detector Position Gain as a function of time (11years data) Survey from Airplane ΔＸ，ΔＹ＝0.1m, ΔＺ＝0.3m Cable delay (optic fiber cable) Accuracy of 100ps by measuring the round trip time in each run Linearity as a function of time (11years data) Detector Gain by muons in each run

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

  7. Linearity check

  8. EnergyDetermination • Local density at 600m • Good energy estimator by M.Hillas E=2.13x1020eV, E >= 1.6x1020eV

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

  10. The Highest Energy Event (2.46 x1020eV, E>1.6x1020eV) on 10 May 2001

  11. S(600) vs Nch Attenuation curve 1018eV Proton Atmospheric depth

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

  13. Proton S600 Intrinsic fluctuation for proton and iron Iron

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

  15. Major Systematics in AGASAastro-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%

  16. 25% 30% Energy Resolution mainly due to measurement errors (particle density measurement and core location determination)not due to shower fluctuation

  17. Energy Spectrum by AGASA (θ<45) 11 obs. / 1.8 exp. 4.2σ 5.1 x 1016 m2 s sr

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

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

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

  21. Arrival Direction Distribution >4x1019eVzenith 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(>3.9x1019eV) and a new doublet(<2.6deg)

  22. Space Angle Distribution of Arbitrary two events >4x1019eV Normalized sigma by Li & Ma 3.2 sigma

  23. Arrival Direction Distribution >1019eV

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

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

  26. ρμ(1000) distribution

  27. Chemical composition study by muons(p+Fe composition assumption; AIRES+QGSJET) • 1017.5eV – 1019eV (Akeno 1km2 array) • Gradual lightening A1: PRELIMINARY (PRELIMINARY) • Above 1019eV (AGASA) • Fe frac.: <40% (@90% CL) Akeno 1km2 (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)

  28. Limits on gamma-ray fraction Assuming 2-comp. (p+gamma-ray) primaries • Gamma-ray fraction upper limits (@90%CL) • 34% (>1019eV)(g/p<0.45) • 56% (>1019.5eV)(g/p<1.27) to observed events Topological defects (Sigl et al. ‘01) (Mx=1016[eV]; flux normalised@1020eV ) Z-burst model(Sigl et al. ‘01) (Flux normalised@1020eV) SHDM-model (Berezinski et al. ‘98) (Mx=1014[eV]; flux normalised@1019eV )

  29. 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/Mpc3 ~ density of AGNs • Chemical composition at 1019eV • Consistent with light component (P) • No gamma ray dominance, γ/all <34%

  30. New Projects for UHECRs Golden Time for UHECRs

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