The SEPT instrument on STEREO

The Solar Electron and Proton Telescope (SEPT) consist of 16 particle telescopes which collect energetic ions and electrons.  SEPT is one of the four instruments of the Solar Energetic Particle (SEP) suite for the IMPACT investigation. SEPT consists of two dual double-ended magnet/foil particle telescopes which measure electrons in the energy range from 30–400 keV and ions from 60–6500 keV. Anisotropy information  is provided by the two separate telescopes: SEPT-E looking in the ecliptic plane along the Parker spiral magnetic field both towards and away from the Sun, and SEPT-NS looking vertical to the ecliptic plane towards North and South. The dual set-up refers to two adjacent sensor apertures for each of the four view directions: one for ions, one for electrons. The double-ended set-up refers to the detector stack with view cones in two opposite directions: one side (electron side) is covered by a thin foil, the other side (ion side) is surrounded by a magnet. The thin foil leaves the electron spectrum essentially unchanged but stops low energy protons.

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Updated June 2010