REM is designed to measure the flux of protons with energies above 30 MeV
and electrons with energies above 1 MeV. REM contains two solid state
detectors measuring the energy transfer of ionozing particles. Two detectors
with different areas and shielding configurations are used making them
selective sensitive to different ranges of particle properties (see figure
below). Both detectors are covered with a spherical dome of aluminium. One
detector has an additional shielding of tantalum. Whereas the detector
without tantalum sees protons as well as electrons, the extra tantalum of the
other detector reduces the penetration of electrons in the relevant energy
range (1-10 MeV) significantly and makes this detector better at monitoring
protons. The charge pulses produced by the particles passing through the
silicon diodes are measured using charge sensitive pre-amplifier and 12-bit
ADCs. In order to reduce the data amount the ADC outputs are compressed into
16-bin histograms.
Cutaway view of the two REM silicon detectors and their shielding.
The REM instrument includes two modules, the detector suite and the
electronics box (see figure below). The detector suite contains the two
solid state detectors and the analog readout electronics. Its physical
dimensions are 13 x 10 x 8 cm and has a weigth of approximately 1 kg. The
electronics box contains the A/D conversion and the digital data processing
electronics and provides the interface of the instrument with spacecraft
telemetry and power. This unit measures 20 x 16 x 8 cm and
weigths 1.8 kg. The maximum total power consumption is less than 5 W.
Layout of the detector suite and the electronics box.
Reference: Nucl. Instr. and Meth. in Phys. Res. A, 386, 825, 1996
(REM_NIMA96.pdf, 0.3 MB)
