A simulation study of a baseline configuration for a next
generation of light,
compact and low power consuming radiation monitors
for future space missions
is presented. The instrument concept studied performs
not only as a radiation
switch, providing ancillary radiation environment
information to the spacecraft,
but also as a scientific instrument, capable of measuring
electrons with
energies between between ~100 KeV and 20 MeV, and
protons and ions with
energies ranging between 0.5 MeV and 150 MeV. A fast
simulation tool based
on a simulation of the instrument using the GEANT4
simulation toolkit is
presented.