470 likes | 636 Views
Cosmic Ray Composition in the Knee Region. H. Tanaka GRAPES-3 Collaboration. Cosmic Rays. TeV. PeV. EeV. ZeV. High Energy Particle from outside of the Earth 10 7 ~10 20 eV Power Low Spectrum E - γ Particle Type Electron, Proton ~ Iron Origin SNR?. Energy Spectrum.
E N D
Cosmic Ray Composition in the Knee Region H. Tanaka GRAPES-3 Collaboration
Cosmic Rays TeV PeV EeV ZeV • High Energy Particle from outside of the Earth • 107~1020eV • Power Low SpectrumE-γ • Particle Type • Electron, Proton ~ Iron • Origin • SNR? Energy Spectrum
Measurement of nuclear composition and their energy spectrum could be one of the key to the solution. Fe H H Fe Knee in Energy Spectrum 1015eV What is the cause of knee ? • Limit of Acceleration • Leakage from the Galaxy • or others ?
Tibet ASγ KASCADE GRAPES-3 Air Shower Experiments GRAPES-3 has both of dens array and large muon detector at the high altitude.
SC MU GRAPES-3 Experiment Location: Tamil nadu, Ooty 2,200m (800g/cm2) Charged Particle (electron) Detector: Plastic Scintillator 1m2,5cm thick x400(8m separations) Muon Detector: 16 detectors (>1GeV) total 560m2 Observation: The number of electrons and the number of muons
Shower Size Size Spectrum LOG N2.5dI/dN [m-2sr-1s-1N1.5] LOG Energy? Composition? MC, muon
Particle Type and Energy Estimated from Observations (MC) Air Shower Simulation • Estimation of primary energy and nuclear mass number from the numbers of electrons and muons • Model dependency for HE-Hadronic interaction Hadronic Interaction Model * SYBILL 2.1 * QGSJET01
M.C. simulation CORSIKA QGSJET01, SIBYLL2.1, QGSJET-II 5 nucleous Proton, He, N, Al,Fe Observation <number of detected muons> N- Ne diagram (M.C.)
Multiplicity Distribution • Al/Feis fixed to 0.8 • Ne: 105.0 - 105.2 • marker • Proton 0.3 • He 0.4 • N 0.3 • Al 0.02 • Fe 0.03 • Observation Good sensitivity of cosmic ray mass
Log10(E/TeV) Log10(Ne) Energy Spectra Analysis MC
Proton Spectrum Comparing with direct measurements is possible
Other Spectra N He Fe Al
Mean Mass Number Fe Al N He H Lower threshold enables data to compare with direct measurements.
Summary • GRAPES-3 can get energy spectra of five groups utilizing muon multiplicity distribution. • Change in proton spectrum and increase in mean mass with energy observed • The results with SIBYLL and QGSJET-II agree with direct and KASCADE measurements. Extend spectrum to higher energy
Air Shower Experiments KASCADE Tibet ASγ GRAPES-3 SPASE-2 BASJE 18
Method of EAS Observation BASJE Bolivia (550g/cm2) 46 SDs (1 or 0.83 m2 each) 12 SDs (4 m2 each) SPASE-2 South Pole (695g/cm2) 30 SDs (0.8m2 each) • KASCADE • Karlsruhe (1020g/cm2) • 252 SDs • Central Detector • Muon Tracking Detector • Tibet Asγ • Tibet (606g/cm2) • 500 SDs (0.5m2 each) • Emulsion chamber • Burst detector 19
Low Flux of Cosmic Ray around Knee • Low Flux • 1 particle in 1m2 in a year (>1015eV) • Poor statistics in Direct Method • Air Shower Observation above 1015eV
Important Matters in Observing Cosmic Ray around Knee • To get enough statistics (Lower flux for higher cosmic rays) • 1 particle in 1m2 in a year Air Shower Observation above 1015eV • Sensitivity of Cosmic Ray Mass • The number of Muon Large Area Muon detector • Solve the Uncertainty of Monte Carlo (high energy phenomena) • Compare the observation with direct measurements Density Shower Array for lower threshold energy GRAPES-3 Experiment
The First Report of Knee “On the Size Spectrum of Extensive Air Showers” G.V. Kulikov and G.B. Khristiansen Journal of Experiment and Theoretical Physics, 1958 Break of size spectrum was reported between 106 – 107. The cause of knee is not yet clear for 50 years. How are Recent Observations?
Low Energy Particle 60GeV High Energy Particle >1013eV ATMOSPHERE , e GROUND Muon Detector Particle Detector Array Air Shower Observation Primary particle MC Observation
Direct Measurements • JACEE • Japanese American Cooperative Emulsion Experiment • Balloon Experiment • 1 - 1000 TeV • The Antarctic • Emulsion Chamber • X-ray film • Lead Plate • RUNJOB • RUssia Nippon JOint Balloon experiment • Balloon Experiment • 10 - 1000 TeV • Kamchatka to Moskva JACEE
Mean Mass Number Much difference among them!
Important Matters in Observing Cosmic Ray around Knee • To get enough statistics (Lower flux for higher cosmic rays) • Sensitivity of Cosmic Ray Mass • Solve the Uncertainty of Monte Carlo (high energy phenomena)
サイズ推定(横方向フィット) x = -11.8m y = 27.3m s = 0.91 シャワーサイズ 1.82×105 検出粒子数 LOG 検出粒子数 NKG関数 コアからの距離(m)
4 layers 58 counters 6m ミューオントラック検出装置 • 検出装置 • 1層58 本の比例計数管 (6m×10cm×10cm) • 交互に組まれた4層で トラックを識別 • 合計16台(560m2) • E>1GeV
EAS Data • Observation • 2000 – 2001 (560days) • Shower Number 6×108 • Shower Rate 13Hz • Shower Selection • Core Location (>80m) • Zenithal Angle θ< 25o • Monte Carlo Simulation • CORSIKA • QGSJET-II (CORSIKA6.50) • SIBYLL 2.1 (CORSIKA6.50) • QGSJET01 (CORSIKA6.02) • Primaries Proton, He, N, Al and Fe
Expanded GRAPES Collaboration • TIFR, Mumbai: H.M. Antia, S.K. Gupta, P.K. Manoharan, P.K. Mohanty, • P.K. Nayak, H. Tanaka, S.C. Tonwar • (2) Osaka City University, Japan: S. Kawakami, Y. Hayashi, S. Ogio, A. Oshima • (3) Aligarh Muslim University, Aligarh: Shakeel Ahmad, Badruddin, R. Hasan • (4) APS University, Rewa: A.P. Mishra, P.K. Shrivastava • (5) BARC, Mumbai: R. Koul, G.N. Shah • (6) J.C. Bose Institute, Kolkata: S. Ghosh, P. Joarder, S. Raha, S. Saha • (7) Gauhati University: R. Baishya, A.G. Baruah, K. Boruah, P.K. Boruah, P. Datta, • J. Saikia • (8) IIA Bangalore: D. Banerjee, P. Subramanian • (9) North Bengal University: A. Bhadra • (10) R.D. University, Jabalpur: R. Agarwal, S.K. Dubey, Santosh Kumar ENDThanks for your kind attention!
Target for present experiment • getting the size spectrum and muon multiplicity distribution • Using M.C., energy spectrum of nucleus can be deduced from these results To achieve this, compact array (high density SD) and muon detectors with large area are required. In this experiment our energy range is overlapping with direct measurement (Balloon exp.). It means we have an anchor point, even though our results are totally M.C. dependent.
http://india-tourism.de/english/index.html • 日印共同研究 (OCU, TIFR) • 観測地点 • 南インド ウーティー • E 76.7° N 11.4° • 2230m a.s.l. (800g/cm2) Location of GRAPES-3 Ooty Air Shower Experiment • Location • Mt. Ooty, South India • E 76.7° N 11.4° • 2,230m a.s.l. (800g/cm2)
Shower Array Muon Detector New Muon Detector 100m2 Hadron Calorimeter Radio Telescope (326MHz) Radio Array (30-70MHz) Neutron Monitor 1km2 Array Future Expansion Plansto observe higher energy cosmic rays
空気シャワーシミュレーションCORSIKA • ハドロン相互作用モデル • DPMJET • GRT + minijet • HDPM • 現象論的モデル • neXus • GRT + minijet • QGSJET • GRT + minijet • 空気シャワー向け • SIBYLL • minijet • 空気シャワー向け • VENUS • GRT(Gribov-Regge Theory) ミューオン数 電子数 110m a.s.l. 2-D Half maximum D.Heck et al., Proc. ICRC27, 233, 2001
ハドロンモデルの影響 1 PeV 鉄 電子数 ミューオン数 両者とも ~10% 程度の違い
QGSJETFe QGSJET Proton SIBYLLFe SIBYLL Proton OBS ハドロンモデル依存性 <検出ミューオン数> • CORSIKA • QGSJET • SIBYLL Log(サイズ)
1.超新星残骸での加速 2.超新星衝撃による加速 3.斜め衝撃波による加速 4.多様な超新星による加速 5.単一の超新星残骸での加速 6.銀河風での再加速 7.火の玉モデル 8.銀河からの漏れ出し 9.銀河からの異常拡散 10.銀河磁場中の拡散と漂流 11.乱流銀河磁場中の移流拡散 12.拡散漂流モデル 13.光分裂と拡散 14.ニュートリノとの相互作用 Knee のモデル 加速 伝播 相互作用
Shower Cascade in the AtmosphereAir Shower Phenomena Primary particle • Nuclear Cascade • p, n, , 0, K, K0, … [decay] • 0 + [8×10-17sec] • + () [3×10-8sec] • High Energy: COLLISION • Low Energy: DECAY • Electromagnetic Cascade • Pair Creation e+ + e- • Bremsstrahlung ee + air Observation
個々の成分の比較 個々の成分で比較できる!
シャワー到来方向 • 検出器へ粒子の入射する時間差から到来方向を推定する • ガンマ線点源の観測時の際は重要
シャワー到来方向推定 時間差 (nsec) (m)
EAS Data • Observation • 2000 – 2001 (560days) • Shower Number 6×108 • Shower Rate 13Hz • Shower Selection • Core Location (>80m) • Zenithal Angle θ< 25o • Monte Carlo Simulation • CORSIKA • QGSJET-II (CORSIKA6.50) • SIBYLL 2.1 (CORSIKA6.50) • QGSJET01 (CORSIKA6.02) • Primaries Proton, He, N, Al and Fe