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Emanuele Pace XUVLab – Dept. Astronomy & Space Science University of Florence - Italy

EUSO in flight calibration. Emanuele Pace XUVLab – Dept. Astronomy & Space Science University of Florence - Italy. EUSO calibration. Lab calibration Sub-systems, pre-flight, vibrations, thermo-vacuum In orbit calibration. Two different objectives and approaches:

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Emanuele Pace XUVLab – Dept. Astronomy & Space Science University of Florence - Italy

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  1. EUSO in flight calibration Emanuele Pace XUVLab – Dept. Astronomy & Space Science University of Florence - Italy EUSO General Meeting - Huntsville (USA), 20 May 2003

  2. EUSO calibration • Lab calibration Sub-systems, pre-flight, vibrations, thermo-vacuum • In orbit calibration • Two different objectives and approaches: • Track simulation and atmosphere sounding • Ground- or airplane-based light sources • Calibration of the telescope performance • Spectroradiometry on board EUSO General Meeting - Huntsville (USA), 20 May 2003

  3. In Palermo EUSO General Meeting - Huntsville (USA), 20 May 2003

  4. Instrument calibration • The telescope or optical system • The focal plane detector • The front-end and trigger electronics Ground based calibration The collected signal for a given incident flux F is: Calibration required! EUSO General Meeting - Huntsville (USA), 20 May 2003

  5. Requirements • Spectroradiometry in the range 300-400 nm • Photon counting regime: Integration time: 200 ns Time resolution: 20 ns Background: < 5 x 104 ph/s/px (<10-2 ph/px) • Uncertainty <10% • Very low impact on the mass budget • Low power consumption • No movable components • Monitor for the light source EUSO General Meeting - Huntsville (USA), 20 May 2003

  6. 125 cm FL1 FL2 FS Ray tracing Input: Transmittance of the Teflon diffuser Total transmittance of lenses 70% Integration time = 200 ns No scattered light Ø FS= 2.5 m Flux on FS = 8 x 109 ph/s = 1600 ph on FS = 0.3 ph / MAPMT = ~10-2 ph / px EUSO General Meeting - Huntsville (USA), 20 May 2003

  7. Ray tracing Lambertian source (106 rays simulation) Wavelength =357 nm Number of pixels7800 EUSO General Meeting - Huntsville (USA), 20 May 2003

  8. Source arrangement EUSO General Meeting - Huntsville (USA), 20 May 2003

  9. LED • GaN, InGaN, AlGaN UV LEDs • Emission wavelengths @ 350 nm, 370 nm, and 393 nm • Photon flux: 1015 ph/s in a narrow beam (15°) • Power consumption: ~ 120 mW • Very lightweight: < 10 g • Commercially available by many companies, such as Nichia Corp., Marubeni Sunnyvale Corp., Nitride Semiconductor Co., Roithner Lasertechnik. EUSO General Meeting - Huntsville (USA), 20 May 2003

  10. Electronics box 30 mm 50 mm Multiple-LED source Si LED’s and photodiode are radiation soft Rad-hard BOX : 4 mm Al EUSO General Meeting - Huntsville (USA), 20 May 2003

  11. Detectors on the Focal surface R1635P head-on PMT from Hamamatsu Corp. PRO • Monitoring the optical performance of the lenses CON • Photomultipliers as unique choise • Long-term detector calibration not available • Impact on mass and power budget EUSO General Meeting - Huntsville (USA), 20 May 2003

  12. Calibration System Obscuration on 2nd Fresnel lens Øobs= 200 mm EUSO General Meeting - Huntsville (USA), 20 May 2003

  13. Arrangements Sketch are not in scale EUSO General Meeting - Huntsville (USA), 20 May 2003

  14. Mass & Power No contingency EUSO General Meeting - Huntsville (USA), 20 May 2003

  15. Next step I suggest and solicitate the discussion on calibrations in view of a Calibration Working Group to coordinate and develop activities on this crucial subject Items Sub-systems vibration tests thermo-vacuum tests pre-flight on orbit ground-based Contributions from WG’s on • Optics • Instrument structure • Simulations • LIDAR • Focal surface detector • Trigger and readout electronics EUSO General Meeting - Huntsville (USA), 20 May 2003

  16. EUSO General Meeting - Huntsville (USA), 20 May 2003

  17. Targets • Transmissivity and uniformity changes of the two Fresnel lenses • Solarization and wavelength bandpass shift of the UV filters • Transmissivity or reflectivity reduction of optical adapter • Variation of the efficiency of the optical adapters+detector system due to vibrations, possible damage, misalignments, increased scattering power, etc. • Variations of the detector gain and photocathode QE • Failure of some photo-detectors • Increase of the scattered light level EUSO General Meeting - Huntsville (USA), 20 May 2003

  18. Transmittance of Teflon EUSO General Meeting - Huntsville (USA), 20 May 2003

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