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Laboratory for Atmospheric and Space Physics

REPTile Instrument Design

The REPTile instrument is a loaded-disc collimated telescope designed to measure energetic electrons and protons with a signal to noise ratio of two or greater. The instrument consists of a stack of four solid-state doped silicon detectors manufactured by Micron Semiconductor. Higher energy particles penetrate deeper into the detector stack and, as they do, they generate electron-hole pairs in the doped silicon. A bias voltage is applied across each detector to accelerate the loosened electrons to an anode, where they are collected and measured by instrument electronics. Using coincidence logic, the electronics determine which detectors the particle impacted, and thus the energy range of the particle.

Key Features:

  1. Instrument measurements
    • Electron differential flux measurements between 0.5-1.5, 1.5-2.2, 2.2-2.9 MeV, and integral flux measurements for >2.9 MeV
    • Proton differential flux measurements between 8.5-18.5, 18.5-25, 25-30.5, and 30.5-40 MeV
    • Time cadence: 6 seconds
  2. Size
    • mass = 1.25kg
    • cylindrical envelope of 4.6cm (diameter) x 6.0cm (length)
  3. Geometric factor: 0.52Sr • cm2
  4. 52° field-of-view
  5. Layered tungsten and aluminum shielding, tantalum baffles, and a beryllium window to prevent false detections from particles outside the energy ranges or field-of-view
  6. Performance characterized by Geant4 simulations and radiation source testing