Medium-Energy Particle Analyzer (MEPA)
The AMPTE CCE Medium-Energy Particle Analyzer (MEPA)
(cross-sectional views)
measured the spectra and composition of magnetospheric particle populations
from 10 keV per nucleon (for oxygen) to more than 6 Mev. The instrument
provides for high background rejection and a geometry factor large enough
( 10**-2 cm**2 sr ) to be sensitive to rare natural species and tracer ions
beyond geosynchronous orbit, while having the ability to operate in the very
high flux regions of the inner magnetosphere. The MEPA telescope measures
time of flight and thus velocity of energetic ions from a thin front foil
to a rear solid-state total-energy detector, determining the incident ion
mass. The telescope was capable of isotopic resolution of hydrogen and
helium, of elemental resolution up through oxygen, and could resolve major
species and groups to beyond iron with 32-sector angular resolution and
temporal resolution of 0.2 - 24 s.