The principal objective of the EPIC (Energetic
Particles and Ion Composition) investigation is to explore the
outer magnetosphere and the distant magnetotail region and obtain
information on the origin, transport, storage, acceleration and
dynamics of suprathermal and non-thermal particle populations.
The instrument contains two main sensor heads. The STICS assembly
(Supra-Thermal Ion Composition Spectrometer) uses a quadrispherical
electrostatic analyzer followed by a foil/solid state detector
time-of-flight (TOF) telescope to measure charge state, mass and
energy of ions with energies of 10 - 230 keV/charge. The ICS
assembly (Ion Composition Subsystem) measures the mass and energy
of energetic ions with energies of less than 50 keV to 3 MeV. It
uses a pair of collimators with sweeping magnets to reject
electrons, followed by TOF and energy analysis. A thin foil/solid
state detector electron telescope measures electrons higher than
30 keV. Directional measurements with a time resolution less than
3 s for all species are possible. A detailed instrument description,
and a complete set of EPIC summary plots from launch to the present,
plus on-line access to the digital data set, is available at the
EPIC link below.