AGASAAGASA

Masahiro TeshimaMasahiro TeshimaMax-Planck-Institut fMax-Planck-Institut füür Physik, Mr Physik, Müünchen, nchen,

GermanyGermany

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 AAkeno keno GGiant iant AAir ir SShower hower AArrayrrayoperated in 1991~2004operated in 1991~2004

111 Electron Det.27 Muon Det.

0 4km

Closed in Jan 2004

AGASA Linearity check after dismantling detectors in 2004 Feb

At Akeno Observatory Central building in 2004 Jan

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)

AGASAD

ete

ctor

Sim

ula

tion

(GEA

NT-3

)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 　　 DeterminationDeterminationLocal density at 600mLocal density at 600m Good energy estimator by M.HillasGood energy estimator by M.Hillas

E=2.1x1020eV

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

S6

00

Intr

insi

c fluct

uati

on

Proton

Iron

AGASA

Energy ResolutionEnergy Resolution

30% 25%

mainly due to measurement errors (particle density measurement and core location determination)not due to shower fluctuation

AGASA The Conversion from S600 to Energy

Muon/Neutrino

Ele. Mag

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 ±± 20% 20%

AGASA

Energy Spectrum by AGASA (θ<45)

11 obs. / 1.3~2.6 exp.

5.1 x 1016 m2 s sr

AGASA Critical review of energy Critical review of energy estimation and spectrumestimation and spectrum

Acceptance of ArrayAcceptance of Array AGASA fast simulation (based on empirical formula and toy simuAGASA fast simulation (based on empirical formula and toy simu

lation)lation) Based on CORSIKA M.C.Based on CORSIKA M.C. Essentially acceptance is saturated Essentially acceptance is saturated No difference No difference

Lateral distribution of showersLateral distribution of showers Lateral distribution determined by experimentLateral distribution determined by experiment Lateral distribution estimated by Corsika M.C.Lateral distribution estimated by Corsika M.C. No differenceNo difference

Attenuation of S(600)Attenuation of S(600) Attenuation curve determined by experimentAttenuation curve determined by experiment Attenuation curve estimated by Corsika M.C.Attenuation curve estimated by Corsika M.C. There is systematic difference of 10-20%There is systematic difference of 10-20%

AGASA S600 attenuation with recent CorS600 attenuation with recent Corsikasika

Overestimation factorcompared with Corsika

We are very close to S600 maximum at 1020eV

AGASA Preliminary spectra with recent CoPreliminary spectra with recent Corsikarsika

No difference in Models and Compositions

Energy shift to lower direction~10% at 1019eV~15% at 1020eV

Above 1020eV11events 5~6 events

Featureless spectrumvery close to E-3

P-SIBYLL (above 1019eV)γ = 2.95 ±0.08 (χ2 / NDF = 8.5/11)

Fe-QGSJET (above 1019eV)γ = 2.90 ± 0.08(χ2 /NDF = 8.5/11)

~10%

~15%

AGASAArrival Direction Distribution >4x10Arrival Direction Distribution >4x101919eVeV

zenith angle <50deg.zenith angle <50deg.

Isotropic in the large scale Isotropic in the large scale Extra-Galactic origin Extra-Galactic originBut, 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 sigma

3.2 sigma excess

AGASA

Arrival Direction Distribution >10Arrival Direction Distribution >101919eVeV

AGASAS

pace

An

gle

S

pace

An

gle

D

istr

ibu

tion

Dis

trib

uti

on

Log E>19.6 Log E>19.4　

Log E>19.2 Log E>19.0

AGASA

AGASA Triplet + HiResAGASA Triplet + HiRes

These events are on the supergalactic plane

Arp299: 40MpcColliding galaxy

NGC3610: 33MpcMerger Remnant

NGC3613: 36MpcAGN Remnant

MAGIC made the observationof these objects,Results will come in ICRC07

AGASA

ρρμμ(1000) distribution(1000) distribution

AGASA

SummarySummary

Super GZK particlesSuper GZK particles Preliminary study with recent CORSIKAPreliminary study with recent CORSIKA

If we evaluate energies with the recent CORSIKAIf we evaluate energies with the recent CORSIKA Energy scale shift down by ~10% at 10Energy scale shift down by ~10% at 101919eV and by ~15% at 10eV and by ~15% at 102020

eVeV 11 events above 1011 events above 102020eV / 1.3~2.6 expected eV / 1.3~2.6 expected

5~6 events / 1.0~1.9 expected 5~6 events / 1.0~1.9 expected

Small scale anisotropy of UHECRSmall scale anisotropy of UHECR The arrival direction of UHECRs is uniform in large scaThe arrival direction of UHECRs is uniform in large sca

lele But AGASA data shows clusters, 1 triplets and 6 doublBut AGASA data shows clusters, 1 triplets and 6 doubl

ets ets granularity granularity Source density ~10Source density ~10-5-5/Mpc/Mpc3 3 ~ density of AGNs ~ density of AGNs