Post on 14-Dec-2015
AGASA Results
Max-Planck-Institut für Physik, München, Germany
Masahiro Teshimafor AGASA collaboration
at 3rd Int. Workshop on UHECR, Univ. Leeds
Cosmic Ray Energy Spectrum
P
γ3K
ΔN
π
GZK mechanism
AGASA Energy Spectrum
Super GZK part.~1/km2 century
AGASAAkeno Giant Air Shower
Array
111 Electron Det.27 Muon Det.
0 4km
Exposure in ICRC2003
Auger
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 AirplaneΔX, ΔY= 0.1m, ΔZ= 0.3m
Linearity as a function of time(11years data)
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
Linearity check
Energy DeterminationLocal density at 600mGood energy estimator by M.Hillas
E=2.13x1020eV, E >= 1.6x1020eV
Third Highest event97/03/30 150EeV
40 detecters were hit
The Highest Energy Event (2.46 x1020eV, E>1.6x1020eV)
on 10 May 2001
Attenuation curve S(600) vs Nch
1018eV Proton
Atmospheric depth
S600 Attenuation curve
0-45°
0-60°
Atmospheric depth
20.0
19.5
19.0
18.5
18.0
S600 Intrinsic fluctuation for
proton and iron
Proton
Iron
The Conversion from S600 to Energy
Muon/Neutrino
Ele. Mag
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%
Energy Resolution
30% 25%
mainly due to measurement errors (particle density measurement and core location determination)not due to shower fluctuation
Energy Spectrum by AGASA (θ<45)
11 obs. / 1.8 exp. 4.2σ
5.1 x 1016 m2 s sr
The Energy spectrum by AGASA Red: well inside the array
(Cut the event near the boundary of array)
AGASA vs HiRes (astro-ph)See new paper: Energy determination in AGASA (astro-ph/0209422)See new paper: Energy determination in AGASA (astro-ph/0209422)
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
Arrival Direction Distribution >4x1019eVzenith angle <50deg.
Isotropic in large scale Extra-GalacticBut, 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)
Space Angle Distribution of Arbitrary two events >4x1019eV
Normalized sigmaby Li & Ma
3.2 sigma
Arrival Direction Distribution >1019eV
Space Angle Distribution
Log E>19.6 Log E>19.4
Log E>19.2 Log E>19.0
Energy spectrum of Cluster events∝E -1.8+-0.3
Cluster Component
ρμ(1000) distribution
Akeno 1km2 (A1): Hayashida et al. ’95 Haverah Park (HP): Ave et al. ’03Volcano Ranch (VR): Dova et al. (ICRC ‘03)HiRes (HiRes): Archbold et al. (ICRC ‘03)
A1: PRELIMINARY
1017.5eV – 1019eV (Akeno 1km2 array)
Gradual lightening
Above 1019eV (AGASA)
Fe frac.: <40% (@90% CL)
Chemical composition study by muons(p+Fe composition assumption; AIRES+QGSJET)
(PRELIMINARY)
Limits on gamma-ray fraction
Gamma-ray fraction upper limits (@90%CL)
34% (>1019eV)(/p<0.45)
56% (>1019.5eV)(/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 )
Assuming 2-comp. (p+gamma-ray) primaries
SummarySuper 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%
New Projects for UHECRs
Golden Time for UHECRs