AGASA Results
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Transcript of AGASA Results
AGASA ResultsAGASA Results
Masahiro TeshimaMasahiro TeshimaMax-Planck-Institut fMax-Planck-Institut füür Physik, Mr Physik, Müünchen, Germanynchen, Germany
for AGASA collaborationfor AGASA collaboration
AGASA
Cosmic Ray Energy SpectrumCosmic Ray Energy Spectrum
P
γ3K
ΔN
π
GZK mechanism
AGASA Energy Spectrum
Super GZK part.~1/km2 century
AGASA AGASAAGASAAkeno Giant Air Shower ArrayAkeno Giant Air Shower Array
111 Electron Det.27 Muon Det.
0 4km
AGASA Exposures of various Exposures of various experimentsexperiments
Auger
AGASA 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)
AGASA Linearity check after dismantling detectors in 2004 Feb
At Akeno Observatory Central building in 2004 Jan
AGASAD
ete
ctor
Sim
ula
tion
(GEA
NT)
Detector Housing (Fe 0.4mm)Detector Box (Fe 1.6mm)Scintillator (50mm)Earth (Backscattering)
vertical θ = 60deg
Detector Response
Energy spectra of shower particles
AGASA
EnergyEnergy DeterminationDetermination
Local density at 600mLocal density at 600m Good energy estimator by M.HillasGood energy estimator by M.Hillas
E=2.13x1020eV
AGASA
The Highest Energy Event The Highest Energy Event 2.5 x102.5 x102020eV on 10 May 2001eV on 10 May 2001
AGASA
Attenuation curveAttenuation curveS(600) vs Nch
1018eV Proton
Atmospheric depth
AGASA
S600 Attenuation curveS600 Attenuation curve
Atmospheric depth
20.0
19.5
19.0
18.5
18.0
AGASA
S6
00
Intr
insi
c fluct
uati
on
Proton
Iron
AGASA The Conversion from S600 to Energy
Muon/Neutrino
Ele. Mag
AGASA
Energy ResolutionEnergy Resolution
30% 25%
mainly due to measurement errors (particle density measurement and core location determination)not due to shower fluctuation
AGASA Major Systematics in AGASAMajor Systematics in AGASAastro-ph/0209422astro-ph/0209422
DetectorDetector Detector Absolute gainDetector Absolute gain ±± 0.7% 0.7% Detector LinearityDetector Linearity ±± 7% 7% Detector response(box, housing)Detector response(box, housing) ±± 5% 5%
Energy Estimator S(600)Energy Estimator S(600) Interaction model, P/Fe, HeightInteraction model, P/Fe, Height ±±15%15%
Air shower phenomenologyAir shower phenomenology Lateral distribution functionLateral distribution function ±± 7% 7% S(600) attenuationS(600) attenuation ±± 5% 5% Shower front structureShower front structure ±± 5% 5% Delayed particle(neutron)Delayed particle(neutron) ±± 5% 5%
TotalTotal ±± 18% 18%
AGASA
Energy Spectrum by AGASA (θ<45)
11 obs. / 1.8 exp. 4.2σ
5.1 x 1016 m2 s sr
AGASA The Energy spectrum by AGASA Red: well inside the array
(Cut the event near the boundary of array)
AGASA
AGASA vs HiRes (astro-ph)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)
AGASA Critical review for energy Critical review for energy determinationdetermination
Fitting the lateral distribution of shower parFitting the lateral distribution of shower particle densityticle density Empirical formula (exclude errors in M.C. but liEmpirical formula (exclude errors in M.C. but li
mited by statistics)mited by statistics)no energy dependenceno energy dependenceLinear dependence on sec(theta)Linear dependence on sec(theta)
lateral distribution obtained by Corisikalateral distribution obtained by Corisika
AGASA
Lateral distributionLateral distribution
Empirical lateral S(600)
Cors
kika
late
ral S
(600
)
Slope parameter eta
AGASA S600 attenuation with recent CorS600 attenuation with recent Corsikasika
Overestimation factor if CORSIKA is right
We are very close to S600 maximum at 1020eV
AGASA Preliminary spectra with recent CoPreliminary spectra with recent Corsikarsika
Sec(theta) =1.0 - 1.2 Sec(theta) =1.2 - 1.4
AGASAComparison of original energy spectrum and new spectra Comparison of original energy spectrum and new spectra
based on Corsikabased on Corsika
Energy shift~10% at 1019eV~15% at 1020eVto lower direction
Above 1020eV11events 5~6 events
Spectrum becomes more featureless
~10% ~15%
AGASA Auger Energy SpectrumAuger Energy Spectrumwith FD calibrationwith FD calibration
AGASACorsika
by Arisaka
AGASA Auger Energy SpectrumAuger Energy Spectrumwith MC energy by Arisakawith MC energy by Arisaka
AGASACorsika
by Arisaka
AGASAArrival Direction Distribution >4x10Arrival Direction Distribution >4x101919eVeV
zenith angle <50deg.zenith angle <50deg.
Isotropic in large scale Isotropic in large scale Extra-Galactic Extra-GalacticBut, Clusters in small scale (But, Clusters in small scale (ΔθΔθ<<2.5deg)2.5deg)
1triplet and 6 doublets (2.0 doublets are expected from random)1triplet and 6 doublets (2.0 doublets are expected from random)
AGASA Space Angle Distribution of Arbitrary Space Angle Distribution of Arbitrary two events >4x10two events >4x101919eVeV
Normalized sigmaby Li & Ma
3.2 sigma
AGASA
Arrival Direction Distribution >10Arrival Direction Distribution >101919eVeV
AGASA
Space Angle DistributionSpace Angle Distribution
Log E>19.6 Log E>19.4
Log E>19.2 Log E>19.0
AGASA
ρρμμ(1000) distribution(1000) distribution
AGASA
SummarySummarySuper GZK particles existSuper GZK particles exist
Preliminary study with recent CORSIKAPreliminary study with recent CORSIKAIf recent CORSIKA describes showers correctly, AGASA energy scaIf recent CORSIKA describes showers correctly, AGASA energy scale will shift down le will shift down
by ~10% at 10by ~10% at 101919eV and by ~15% at 10eV and by ~15% at 102020eV on averageeV on averageSpectrum seems to be more featureless (in preliminary study) ?? Spectrum seems to be more featureless (in preliminary study) ?? Discrepancy between AGASA and HiRes becomes less significantDiscrepancy between AGASA and HiRes becomes less significant
Small scale anisotropy of UHECRSmall scale anisotropy of UHECR The arrival direction of UHECRs is uniform in large scaleThe arrival direction of UHECRs is uniform in large scale But AGASA data shows clusters, 1 triplets and 6 doublets But AGASA data shows clusters, 1 triplets and 6 doublets gra gra
nularitynularity Source density ~10Source density ~10-5-5/Mpc/Mpc3 3 ~ density of AGNs ~ density of AGNs Re-analysis is on-going with new shower front structure (but verRe-analysis is on-going with new shower front structure (but ver
y slow)y slow)
Chemical composition at 10Chemical composition at 101919eVeV Consistent with light component (P)Consistent with light component (P) No gamma ray dominance, No gamma ray dominance, γγ/all/all <34% <34%