The Solar Energetic Particle (SEP) instrument is part of the Particles and Fields
Package and determines the impact of SEPs on the upper atmosphere.

Goals:
* Determine SEP input into the atmosphere as a function of altitude
* Determine SEP heating, ionization, and sputtering of upper atmosphere
* Detect the highest energy pickup ions (>30 to 100s of keV)

Observations:
* Characterize solar particles in an energy range that affects upper atmosphere and ionospheric processes (~120 – 200 km)
* Time resolution adequate to capture major SEP events ( less 1 hour)

Technical details and heritage:
* Two dual double-ended telescopes
* Four look directions per species, optimized for parallel and perpendicular Parker Spiral viewing
* Protons and heavier ions from ~25 keV to 12 MeV
* Electrons from ~25 keV to 1 MeV
* Energy fluxes 10 to 106 eV/cm2-sec-ster-eV
* Better than 50% energy resolution
* Heritage from (nearly identical to) SST on THEMIS