AGASAResults阿嘉莎的结果.pptx

OutlinePhysics motivationActivities at Akeno ObservatoryEnergy determination&spectrumShower properties&analysisSystematic error in energy estimationComparison with other results(HiRes&A1)Muon component&chemical compositionGamma-ray shower propertiesChemical composition&gamma-ray flux limit estimationSummary&outlookPhysics motivationUnderstanding nature&origin of UHECRs(1019eV)Energy spectrumArrival direction distributionChemical compositionSuper GZK particlesincl.highest energy cosmic rays(1020eV)Bottom-up scenariosAGNs/GRBs/Galactic clusters etc.Hadronic primaries predictedTop-Down scenariosTopological defectsSuper heavy dark matter Z-burstGamma-ray+nucleon 1ries predictedSource location still not identified,.but.pUHECR CMB N+(E0 5x1019eV)Arrival direction distribution(4x1019eV;4x1019eV within 2.5)6 doublets()&1 triplet()observed Against expected 2.0 doublets(Pch 1020eVLog E19.03.4Space angle distribution of eventsSignificant peak 0 degreeimplying presence of compact EHECR sourcesLog E19.64.4Institute for Cosmic Ray Research,University of Tokyo (Kashiwa)Masaki Fukushima,Naoaki Hayashida,Hideyuki Ohoka,Satoko Osone,Makoto Sasaki,Masahiro Takeda,Reiko ToriiKinki University(Osaka)Michiyuki ChikawaUniversity of Yamanashi(Kofu)Ken Honda,Norio Kawasumi,Itsuro TsushimaSaitama University(Saitama)Naoya Inoue Musashi Institute of Technology(Tokyo)Kenji KadotaTokyo Institute of Technology(Tokyo)Fumio KakimotoNishina Memorial Fundation(Tokyo)Koichi KamataHirosaki University (Hirosaki)Setsuo KawaguchiOsaka City University (Osaka)Saburo Kawakami RIKEN (Wako)Yoshiya Kawasaki,Naoto Sakaki,Hirohiko M.ShimizuEhime University (Matsuyama)Satoko Mizobuchi,Hisashi YoshiFukuki University of Technology (Fukui)Motohiko Nagano Communication Research Laboratory(Tokyo)Masahiko Sasano National Institute of Radiological Sciences(Chiba)Yukio Uchihori Chiba University (Chiba)Nobuyuki Sakurai,Shigeru YoshidaMax-Planck-Institute for Physics(Munich)Kenji Shinozaki,Masahiro TeshimaUniversity of Chicago (Chicago)Tokonatsu YamamotoAGASA CollaboratorsWe are INTERCONTINETAL collaboration among 31(all Japanese)scientists from 17 institutes in 3 nationsJapanFederal Republic of GermanyUnited States of AmericaAkeno ObservatoryInst.for Cosmic Ray Research,Univ.of TokyoAkeno,Yamanashi Japan(100km west of Tokyo)Lat.3547N,Long.13830E Altitude 900mAtom.depth 920 g/cm2 Ave.pressure 910hPaTemp.10+30Muon detectorstation Tokyo東京東京 Vladivostok Yakutsk Sea of Okhotsk海 Pacific Ocean太平洋TA Prototype TsukubaAkeno明野明野 M.Fuji富士山富士山LeadburgerMain BuildingCosmic Ray Imaging System AUGER Water TankAGASA(Akeno Giant Air Shower Array)8kmDetector station111 surface detectorsEffective area 100km2Optical fibre cable connection to observatory27 muon detectorsSouthern region 30km2 coverage Operation Feb.1990Dec.19954 separate-array operationDec.1995Jan.2004 Unified operationSBNBABTBSurface detector5cm thick scintillatorHamamatsu 5”R1512 PMTMuon detectors(2.810m2;south region)1420 Proportional countersShielded by 30cm Fe or 1m concreteThreshold energy:0.5GeVxsecTriggered by accompanying surface detectorShower front structure(empirical)Modified from Linsley formula Delay time behind shower planeTd(R)ns=2.6(1+R/30m)1.5(R)-0.5Shower front thicknessTs(R)ns=2.6(1+R/30m)1.5(R)-0.3Lateral distribution (empirical)Modified Linsley formula(R)=C(R/RM)(1+R/RM)()1+(R/1000)2 C:Normalisation constant,=1.2,=0.6RM:Moliere unit Akeno(=91.6m)=(3.970.13)(1.790.62)(sec 1)Fluctuation of observed particle number 2=+0.25 2+(=scin2+rest2+stat2)sec1.1S(600)=10,30m2Energy estimating relationshipsEnergy vs.S(600)for vertical showersDai et al.s MC result by COSMOS+QCDJET(1988)E0 eV=2.031017 S0(600)S(600)Attenuation curveEmpirical relationship(equi-intensity cut method)S (600)=S0(600)expX0/1(sec1)X0/2(sec1)2X 0:Atmospheric depth AKeno(920 g/cm2)1=500 g/cm2 2 =594 g/cm221019eV11019eVEvent reconstruction1.Centre of gravity in ch distribution a priori core location2.Arrival direction optimisation(fitting shower front structure)3.Core location estimation(fitting lateral distribution)4.Iterative recalculation of Steps 2&35.S(600)S0(600)translation6.Energy estimation by S0(600)vs.E0 relationEvent sampleEvent sampleEvent selection criteria(standard)Dataset:February 1990 January 20041.Energy:1017eV (1018.5eV for spectrum)2.Zenith angle:45 3.Core location:inside AGASA boundary4.Number of hit detector 65.Good reconstruction 2 5for arrival direction fitting 2 1.5for core location fittingCore location distribution(1018.5eV)Before&after unificationAperture:110km2sr extended to 160 km160 km2srsr95.1204.0190.295.12Exposure(up to May 2003)AGASA Exposure 5.4x1016 m2 sec sr above 1019eV within 45AGASA has higher exposure than HiRes below 3x1019eVAGASA detectorReconstruction accuracy(Energy resolution,Angular resolution)Energy resolutionE0/E0=30%1019.5eVE0/E0=25%1020eVAngular resolution=2.0 1019.5eV=1.3 1020eVLog(EnergyeV)1.0 0.0 1.0 0.0 1.020151050Counts%/bin8642 018 19 20 Log(EnergyeV)90%68%Open angle Energy spectrum (45)Super GZK-particles exist11events above 1020eVExpected 1.9 event on GZK assumption for uniform sourcesDetector calibrationPWD monitored every RUN(10h)Information taken into account in analysisStability of detectorGain variation(peak of PWD):0.7%Linearity variation(slope of PWD):1.6%Linearity variation(11yr)Pulse width distri.(10hr)Gain variation(11yr)a:Slopet1:PeakCf./=a/Channel 0.5nsDetector simulation(GEANT)Detector container(0.4mm iron roof)Detector box(1.6mm iron)Scintillator(5cm thick)Earth(backscattering)Detector response understood at 5%accuracyEnergy conversionMuon/neutrinoEle.Mag90%90%primary energy carried by EM componentprimary particle&model a few%dependence S(600)depending less on primary particle/modelAIRES+QGSJET98/SIBYLL for p&FeEnergy dispersion in atmosphere Energy conversion factorRef.Model1ryabDai et al.88 COSMOS QCDJETp2.031.02Single=electron(900m)Nagano et al.99(CORSIKA5.621)QGSJET98p2.071.03Single=PH peak(900m)Fe2.341.00SIBYLL1.6p2.301.03Fe2.191.03Sakaki et al.01(AIRES2.2.1)QGSJET98p2.171.01Single=PW peak(667m)Fe2.151.03SIBYLL1.6p2.341.04Fe2.241.02E0=a 1017eVx S(600)bPresently assigned primary energy:10%1 2%Most conservative(We need to push up current energy)S(600)attenuation curve4520.019.519.018.518.0AIRES code+QGSJET/SIBYLL model for p/Fe S(600)attenuating rather slowlyCorrection factor less than 2 up to 45 zenith angleS(600)attenuation curve consistent between data&MCDepending less on 1ry particles or interaction modelsError on energy estimation:5%45Shower phenomenology effects(shower front thickness/delaying particles)Shower front thicknessParticle arrival time distri.2km(2x1020eV)Delaying particlesOverestimation effects Important far away from core Data between several 100m 1kmdominant in energy estimationEffect of shower front thickness+5%5%Effect of delaying particles+5%5%Major systematics in AGASA energy DetectorAbsolute gain0.7%Linearity7%Detector response(container,box backscattering)5%Energy estimator S(600)Interaction model,primary particles,altitude10%12%Shower PhenomenologyLateral distribution7%S(600)attenuation5%Shower front structure+5%5%Late arriving particles+5%5%Total18%Systematics is energy independent above 1019eVFeature of spectrum can hardly change that extends beyond GZK cutoff.Consistency check in different apertureInside arrayWell inside array(2/3 AGASA)No systematic found in different aperturesEHECR spectrum extension beyond GZK cut-offRecent spectra(AGASA vs.HiResTsukuba ICRC)HiRes:Bergman et al.032.5 sigma discrepancy between AGASA&HiResEnergy scale difference by 25%vs.HiRes-stereovs.HiRes-Ivs.HiRes-IIComparison of Ne vs.S(600)in Akeno 1km2 arrayE0=8.51018 eV by Ne=5.13109E0=9.31018 eVby S(600)=45.7/m2 E0 eV=3.91015(Ne/106)0.9Derived from attenuation curve comparison with Chacalaya(5200m;540g/cm2)experimentFairly good agreement between experiment&MCAGASA vs.A1 comparisonChemical composition studyUHECR composition is key discriminator of models Muons in giant air shower are key observable for AGASA Presence of Super-GZK particlesNo location identified as their sourcesPossibilities of Top-down models(TDs,Z-burst,SHDM)Gamma-ray shower propertiesFewer muon content(photoproduced muon)Landau-Pomeranchuk-Migdal(LPM)effect(3x1019eV)Slowing down shower developmentInteraction in geomagnetic field(several x 1019eV)Accelerating shower developmentLPM effect extinctionIncident direction dependence2000 g/cm20 g/cm2500 g/cm21020eV Gamma-ray(geomag.Interacted)1020eV Proton1020eV Gamma-ray(LPM effect)1000 g/cm2Simulated with MC by Stanev&VankovAverage S(600)vs.energy relationship for gamma-rays(Akeno)Gamma-rayenergy underestimation30%1019 eV50%1019.5 eV(Maximum LPM effct)30%1020 eV(Recovered by geomag.effect)rm(R)=C(R/R0)-1.2(1+R/R0)-2.52(1+(Rm/800)3)-0.6 ,E0=1017.51019eV R0:Characteristic distance(280m q=25o)Lateral distribution function obtained by A1 Experiment (Hayashida et al.1995)Lateral distribution of muonsNo significant change in shape of LDM up to 1020eVEmpirical formulaePrimary mass estimatorLateral distributionSAMPLECharged particle:Muon:Muon density at 1000mrm(1000)Fitting muon data in R=800-1600m to LDMError40%E0=1.8x1020eVrm(1000)=2.4/m2Muon density1000m r(1000)20%to total charged particlesFeasible mass estimator for UHECRsAnalysisDataset(13 December 1995 31 December 2002)E01019eV Zenith angle:q36Normal event quality cuts 2 muon detectors in R=800m1600m rm(1000)Statistics129 events above 1019eV 19 events above 1019.5eVSimulationsProton/iron primaries(AIRES2.2.1+QGSJET98)Gamma-ray primaries(Geomag.+AIRES+LPM)Geomagnetic field effect Significant above 1019.5eVCode by Stanev&VankovLPM effectSignificant above 1019.0eV Included in AIRESDetector configuration&analysis processr rm m(1000)distribution(E01019eV)Average relationship rm(1000)m2=(1.260.16)(E0eV/1019)0.930.13Consistent with proton dominant component 1919.52020.5Log(Energy eV)2101Log(Muon density1000mm2)Akeno 1km2(A1):Hayashida et al.95 (Interpretation by AIRES+QGSJET)Haverah Park(HP):Ave et al.03Volcano Ranch(VR):Dova et al.(present conf.)HiRes(HiRes):Archbold et al.(present conf.)Present result (90%CL)Fe frac.:35%(1019 1019.5 eV)1019eV)(g/p1019.5eV)(g/p95%live-ratio Systematic errors in energy determination 18%independent of energy(1019eV)Super-GZK particles do exist11 events observed 1020eV against 1.9 on GZK assumption Energy spectrum remains extending beyond GZK cut-offConventional GZK mechanism can hardly explain!Chemical compositionGradual lightening between 1017.5&1019eVLight component favoured 1019eV(AIRES+QGSJET)Gamma-ray dominance negative at highest energiesFraction of gamma-rays 1019.5eV)(AIRES+QGSJET)Another approach(Energy underestimation for gamma-rays)LPMGMFq=24.6Effects on UHE Gamma-rayLPM effect(3x1019eV)Geomagnetic effect (5x1019eV)Possible anisotropy in the sky expected for UHE gamma-raysNo indication found for UHE gamma-rays (present low statistics)Possible approach for future large-scale experimentsAkeno sky up to 45o This slide was shown for discussionRubtsovs talk