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■ Observation ◇ Detector : Emulsion Chamber ◇ Balloon Flights : 14 Flights

11-18 August 2011, 32nd ICRC , Beijing. High-energy Electron Observations from 30 GeV to 3 TeV with Emulsion Chambers T. Kobayashi ( Aoyama Gakuin U ) , Y. Komori ( Kanagawa U of HS ) , K. Yoshida ( Shibaura IT ) and J. Nishimura ( ISAS/JAXA, Japan ). ■ Observation

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■ Observation ◇ Detector : Emulsion Chamber ◇ Balloon Flights : 14 Flights

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  1. 11-18 August 2011, 32nd ICRC , Beijing • High-energy Electron Observations • from 30 GeV to 3 TeV • with Emulsion Chambers • T. Kobayashi (Aoyama Gakuin U), Y. Komori (Kanagawa U of HS), • K. Yoshida (Shibaura IT) and J. Nishimura (ISAS/JAXA, Japan) ■ Observation ◇ Detector : Emulsion Chamber ◇ Balloon Flights : 14 Flights ■ Data Analysis ◇ Event Identification : Starting Point View, etc ◇ Energy Determination : Transition Curve ◇ Correction : Atmospheric Electron, etc ■ Resultand Discussion 　　　◇ Electron Energy Spectrum ◇ Diffusion Model and Nearby Sources

  2. Observation : Emulsion Chamber (ECC) Configuration Chamber Design Chamber Size 40 cm × 50 cm Thickness 8 cm ( ～ 9 r.l. ) Lead plate : Shower Development X-ray Film : Event Detection Film type Threshold Non-Screen type 600-800 GeV Screen type 200-400 GeV Nuclear emulsion plate : Event Identification, Energy Determination Advantage of ECC A wide field of view ⇒　Large SΩ Thin thickness ⇒ Large SΩ Selection Criteria ・ Zenith Angle < 30, 45, 60° ・ Pass through Top and Bottom

  3. Observation : Balloon Flights 《Flight List》 1968 - 2001 14 Flights Total SΩT = 8.19 m2-sr-day in TeV region Haranomachi, Sanriku, Japan Palestine, TX, USA Sanriku, (1988 : Uchinoura) Japan SΩT with Energy Corrections ▶ Atmospheric electrons ▶ Bremsstrahlung energy loss Residual Atmosphere 4.0 ～ 9.4 g/cm2

  4. Event Identification Consistency Check Starting Point Distribution Observed Data & Theory with LPM effect Electron Gamma ray Proton Electron Identification Criteria ・ Single track exists at the top emulsion plate ・ produce a e+e- pair at the starting point + within 1 r.l. : 90 % probability + double pairs : 5 % probability above 1 TeV ・ A pure electromagnetic shower + not single or multi core structure + the number simply increase to max Observed Data agree with the expectation from LPM effect Proton rejection power : 1 ×105 in TeV region

  5. Electron Energy ∝ Integrated Track length Energy Determination Counting the electron number within a circle of radius 100 μm at each layer Transition Curve(vertical shower) Monte-Carlo Simulation (EPICS) & CERN-SPS data : 50 GeV , 200 GeV Energy Resolution of ECC MC Simulation & CERN DATA

  6. Correction : Atmospheric Electrons Atmospheric Electron Contribution to Primary Electron Observation Atmospheric Gamma-ray Spectrum MC Simulation from Primary Nuclei is 20% lower than Our Data Atmospheric Electron Spectrum TeV electron Observations require the higher altitude Atmospheric Electron / Gamma-rayRATIO Dalitz electrons contribute a constant value of 5 ×10-3 Dalitz electrons contribute ～ 10% at 4 g/cm2

  7. PrimaryElectronEnergySpectrum Final Result of ECC

  8. Discussion : Sources of Cosmic-ray Electrons Source (SNR) Candidates Diffusion Model : Nearby Sources (SNRs) + Distant component 《Example》 Transport Parameters ▶ Diffusion Coefficient : 2×1029(E/TeV)0.3 cm2/s Distant component : Source Parameters ▶ Electron Max Energy : 20 TeV ▶ SNR Age : 5×103 yr 《Example》 Diffusion Coefficient : 2×1029(E/TeV)0.3 cm2/s Expected Flux at 3 TeV

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