Transcript The Highest Energy Cosmic Rays and Future project

AGASA Results
Max-Planck-Institut für Physik, München, Germany
Masahiro Teshima
for AGASA collaboration
at 3rd Int. Workshop on UHECR, Univ. Leeds
Cosmic Ray Energy Spectrum
AGASA Energy Spectrum
P
γ3K
Δ
Ｎ
π
GZK mechanism
Super GZK part.
~1/km2 century
AGASA
Akeno Giant Air
Shower Array
111 Electron Det.
27 Muon Det.
0
4km
Exposure in ICRC2003
Auger
Detector Calibration in
AGASA experiment
Detector Position
Survey from Airplane
ΔＸ，ΔＹ＝0.1m, ΔＺ＝0.3m
Cable delay
Gain as a function of time
(11years data)
(optic fiber cable)
Accuracy of 100ps by measuring the
round trip time in each run
Detector Gain by muons in each run
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)
Detector
Response
Energy spectra of shower particles
vertical
θ = 60deg
Linearity check
Energy Determination
Local density at 600m

Good energy estimator by M.Hillas
E=2.13x1020eV, E >= 1.6x1020eV
Third Highest event
97/03/30 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
0-60°
20.0
19.5
19.0
18.5
18.0
0-45°
Atmospheric depth
S600 Intrinsic
fluctuation for
proton and iron
Proton
Iron
The Conversion
from S600 to Energy
Muon/Neutrino
Ele. Mag
Major Systematics in AGASA
astro-ph/0209422
Detector
 Detector Absolute gain
 Detector Linearity
 Detector response(box, housing)
Energy Estimator S(600)
 Interaction model, P/Fe, Height
Air shower phenomenology
 Lateral distribution function
 S(600) attenuation
 Shower front structure
 Delayed particle(neutron)
Total
± 0.7%
± 7%
± 5%
±15%
±
±
±
±
7%
5%
5%
5%
± 18%
Energy Resolution
mainly due to measurement errors (particle density
measurement and core location determination)
not due to shower fluctuation
30%
25%
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)
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
Arrival Direction Distribution >4x1019eV
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(>3.9x1019eV) and a new doublet(<2.6deg)
Space Angle Distribution of
Arbitrary two events >4x1019eV
Normalized sigma
by Li & Ma
3.2 sigma
Arrival Direction Distribution >1019eV
Space Angle Distribution
Log E>19.0
Log E>19.2
Log E>19.4
Log E>19.6
Energy spectrum of Cluster events
∝E -1.8+-0.3
Cluster Component
ρμ(1000) distribution
Chemical composition study by muons
(p+Fe composition assumption; AIRES+QGSJET)
A1: PRELIMINARY
1017.5eV – 1019eV
(Akeno 1km2 array)

Gradual lightening
(PRELIMINARY)
Above 1019eV (AGASA)

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)
Fe frac.: <40% (@90% CL)
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)

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 )
56% (>1019.5eV)
(g/p<1.27)
to observed events
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%
New Projects for UHECRs
Golden Time for UHECRs