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

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

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

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

4 Exposure in ICRC2003 Auger

5 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)

6 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

7 Linearity check

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

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

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

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

12 S600 Attenuation curve 0-45° 0-60° Atmospheric depth

13 S600 Intrinsic fluctuation for proton and iron Proton Iron

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

15 Major Systematics in AGASA astro-ph/ 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 Energy Resolution 30% 25% 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 m 2 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/ )

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

21 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)

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

23 Arrival Direction Distribution >10 19 eV

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

25 Energy spectrum of Cluster events ∝ E Cluster Component

26 ρ μ (1000) distribution

27 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 eV – eV (Akeno 1km 2 array) Gradual lightening Above eV (AGASA) Fe frac.: <40% CL) Chemical composition study by muons (p+Fe composition assumption; AIRES+QGSJET) (PRELIMINARY)

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

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 /Mpc 3 ~ density of AGNs Chemical composition at eV 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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