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How giant Air Showers can be observed from space with a fluorescence telescope like JEM-EUSO

How giant Air Showers can be observed from space with a fluorescence telescope like JEM-EUSO. Sylvie Dagoret-Campagne LAL. FJPPL 2010, June 15th 2010. The JEM-EUSO collaboration. Outline of the talk. The Physics Air Showers, Luminous Atmospheric phenomena, Fast meteors,

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How giant Air Showers can be observed from space with a fluorescence telescope like JEM-EUSO

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  1. How giant Air Showers can be observed from space with a fluorescence telescope like JEM-EUSO Sylvie Dagoret-Campagne LAL FJPPL 2010, June 15th 2010 FJPPL10, LAPP Annecy, June 15-17 2010

  2. The JEM-EUSO collaboration FJPPL10, LAPP Annecy, June 15-17 2010

  3. Outline of the talk The Physics • Air Showers, • Luminous Atmospheric phenomena, • Fast meteors, The JEM-EUSO Instrument • The lenses • The focal surface • The photodetectors • The Air shower signals • The Electronics • The Trigger Energy calibration Acceptance FJPPL10, LAPP Annecy, June 15-17 2010

  4. I. The Physics I.A Cosmic ray /Air Shower physics IB Luminous phenomena in upper atmosphere FJPPL10, LAPP Annecy, June 15-17 2010

  5. I.1. The Air Showers (Cosmic rays Physics) From P. Auger spectrum • Expect to collect at least 2000 events above GZK cutoff (7 1020eV), • Point like source search within the GKZ horizon (50-100 MPC),  • Anisotropy studies, • Measure the spectrum from various sky region (ΔE/E: 30%  20%), • Composition studies (expect to achieve ΔXmax << 50g/cm2) N(E>1020eV) ~ 1000 / 5years ? Uniform sky  exposure Simulation of 2000 events Clustered like 42 AGN FJPPL10, LAPP Annecy, June 15-17 2010

  6. I.2 Slow Luminous phenomena in the upper atmosphere FJPPL10, LAPP Annecy, June 15-17 2010

  7. I.3 Slow phenomena : meteors JEM-EUSO is a very sensitive micro meteor detector (10-6 g – 1 g, v=12km/s – 100 km/s) M -> 18 for JEM-EUSO whereas usual optical detector reach M=6 5 – 100 / hour Micro meteors are brighter in UV FJPPL10, LAPP Annecy, June 15-17 2010

  8. II. The Instrument Collection surface: Scoll = 5m2 (2m x 2.6m) Field of View: FOV ~ ±30° x ±30° Pixels: ~ 3.5 x 105 pixels FOV(pixel) =0.1° (~700 m) Collection time sampling: τcoll= 2.5 μs (~700 m) • II.1 the lenses • II.2 the photo detectors • II.3 The electronics • II.4 The trigger Actual Focal surface shape FJPPL10, LAPP Annecy, June 15-17 2010

  9. 70% 93% 7% 30% Number of photoelectrons Detected versus time 80 μs – 20 km II.1An Air Shower event in JEM-EUSO (1020eV, 45°) JEM-EUSO sees a factor 10-3 photons less Auger telescopes ! Nb photo electrons • Event view in Focal Plane • pixel size δ=0.1° • 3D view of an Air Shower • δτ =2.5 μs (GTU for Gate Time Unit) FJPPL10, LAPP Annecy, June 15-17 2010

  10. II.2 The lenses • 3 Fresnel lenses (large diameter and short focal distance and thinness and lighter) • Two curved double-sided (front and rear) • One Flat (central) • One Fresnel surface for light ray focusing • One diffraction surface for aberration correction by diffractive effect (cut at 10nm accuracy) • Extremely good focusing within 2.5 mm Ø (within pixel size) • Two possible materials • PMMA (n~1.50  T 0.93) • CYTOP (n~1.35  T ~0.98) Rear lense PMMA Middle lense PMMA Cut in Japan Test in NASA/MSFC Toshiba manufacturing machine in IKEGAMI Mold Corp FJPPL10, LAPP Annecy, June 15-17 2010

  11. II.3 The Photodetectors : the new MAPMT M64 from Hamamatsu New M64 Courtesy from Riken Photometric test bench at APC/FRANCE (2010) 3mm~pixel Ø Total efficiency (quantum and collection) > 30% Sharp and uniform spatial response Negligible signal dispersion to neighbouring pixels < 5% High gain ~106 FJPPL10, LAPP Annecy, June 15-17 2010

  12. II.4 Observed signal for a shower Air Shower signal (1020 eV) • JEM-EUSO is a photoelectron “hungry detector” • The best resolution on the signal can be achieved by photon counting (for Air Showers), with limited dynamic range, • Large dynamic range to catch atmospheric phenomena Extremely small number of photoelectrons ~2000 photons a pupil  100-200 photoelectrons  15-30 photoelectrons in a pixel-time unit bin FJPPL10, LAPP Annecy, June 15-17 2010

  13. II.5 Electronic of the Focal Surface 400 kHz MAPMT 64 pixels Hammatsu & Riken Block of 4 MAPMT And 4 ASICs Riken/LAL/EWHA SPACIROC ASIC + LAL/Omega/France + Riken/Japan Focal Surface 5000 MAPMT 3.5 105 pixels • SPACIROC • Low power consumption < 0.5 mW/channel • « On » permanently (no power pulsing), • Digitization done inside by counters, not by ADC • Fast 2 photon separation ~10 ns • Withstands high rate transfer : 400 kHz • High dynamic range (Shower  lightning) FJPPL10, LAPP Annecy, June 15-17 2010

  14. II.6 Front-End Board (the EC) SPACIROC: • ASIC “SPACIROC” Co-design with Riken/Japan (NDA signed), • Challenges : fast counting (100MHz),high dynamic range, low power consumption • Layout and simulation done at LAL • First prototype submitted to foundry in March 10 • First test to be done in June with a standard packaging • Then packaging in BGA, • Design of the board called EC • Collaboration with Riken/Japan,EWHA/Korea, INFN-mechanics • Mass Production tests (2 x 5000 ASICs) • Spatial Qualification tests • Optical calibration test participation The Elementary cell (2x2 MAPMT + 4 ASICs): UV FJPPL10, LAPP Annecy, June 15-17 2010

  15. II.7 Main night Background Sky background: • nightglow, • Zodiacal light, • Stars, planets, • Moon, • Cities, Big city TUS 300-600 γ per cm2 sr s Irreducible background: 40 MHz/pixel 100 pe/PMT/GTU 1.5 pe/pixel/GTU Need a trigger with high background rejection factor FJPPL10, LAPP Annecy, June 15-17 2010

  16. II.8 Trigger hierarchy 1 to 2 pe per pixel per GTU 400 kHz/channel Sky background, ASIC SPACIROC output Level 0 FPGA/PDM Track search Algorithm over 2300 pixels during 9 GTU (EWHA/Italy) 7Hz/PDM (3. 10-3 Hz/channel) BG Rejection factor 108 Level 1&2 DAQ Shower Pattern recognition based on Statistical algorithm (LAL,Germany) 0.1 Hz/Full detector 6 10-3 Hz/PDM BG rejection factor ~ 1000 Level 3 Air Shower rate 10 -3 Hz FJPPL10, LAPP Annecy, June 15-17 2010

  17. km2.sr 107 106 105 104 3 years in tilt mode 10 6 Linsley (km2 sr year) Factor 5 corresponding To 20% duty cycle of fluorescence JEM-EUSO Duty cycle 20% Auger North : 40 103 km2 sr Auger South: 7.103 km2 sr FJPPL10, LAPP Annecy, June 15-17 2010

  18. JEM-EUSO Exposure of various Cosmic Rays observatories 106 Linsley For undestanding the GZK suppression 1.2x106 Linsley FJPPL10, LAPP Annecy, June 15-17 2010

  19. III. Energy calibration FJPPL10, LAPP Annecy, June 15-17 2010

  20. III.1Energy – optical calibration of the detector Calibration at ground : Calibration in Flight: Relative optical calibration On flight of the focal surface Absolute calibration Of all pixels at ground • MAPMT: • photon detection efficiency εγ • Gain G Stability Controlled By a NIST Lense transmission Relative calibration • fast MAPMT sorting according G and εγ • uniformity scan all the pixels of a set of PMT (called a PDM : 48 x 48 pixels) FJPPL10, LAPP Annecy, June 15-17 2010

  21. III.2Fluorescence yield “calibration” by LAL/APC groups 10% • Measurements@LAL in 2011 • sphere filled by N2 • light detection by a spectrometer • Pressure variation 1atm 0.01 atm • Accuracy 15 %  5% N2 2011 FJPPL10, LAPP Annecy, June 15-17 2010

  22. Acceptance control and estimation 625 km 430 km FJPPL10, LAPP Annecy, June 15-17 2010

  23. III.3Cloud monitoring for light attenuation estimation and acceptance calculation • Clear sky coverage for JEM-EUSO ~30% • Shower maximum must be above cloud top height, • Clouds reduce the acceptance. • Cloud monitoring is helpfull shower max altitude vs zenith angle FJPPL10, LAPP Annecy, June 15-17 2010

  24. III.4 Atmosphere calibration : clouds and aerosols • Large FoV IR camera (λ=10μm): • Cloud altitude (from Temperature for Cerenkov peak time reference) • Evaluation of instantaneous acceptance • ΔT=±3°K  Δh=±1km • LIDAR (λ=350 nm) • IR camera calibration • Δh=±200m  ΔT=±1.4°K • Cerenkov reflection for OD>1 • Optical depth correction when OD < 1 • Aperture accuracy (h=±500) < 2.5% FJPPL10, LAPP Annecy, June 15-17 2010

  25. Conclusion about JEM-EUSO Physics: wide range of themes astrophysics and cosmic rays (fast signals) atmospheric physics upper atmosphere luminous phenomena (very slow), cloud optics and its monitoring, meteors Detector construction : Very tight collaboration France(LAL/APC)-JAPAN/RIKEN Front-End electronics : ASIC and electronic board, Detector Optical calibration : ground absolute calib and in flight calib Atmosphere: extremely Accurate Fluorescence yield “calibration” or experiment, Analysis Interest in Clouds and aerosol monitoring analysis for acceptance determination. FJPPL10, LAPP Annecy, June 15-17 2010

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