POLIX, developed by the Raman Research Institute (RRI), Bengaluru is a Thomson X-ray Polarimeter, which aims to measure the degree
and angle of polarization of cosmic X-ray sources in the medium X-ray energy range (8-30 keV).
The instrument consists of a collimator, a Beryllium scatterer surrounded by Xenon filled X-ray proportional counters as X-ray
detectors, and signal processing electronics. During source observation, the instrument is rotated around the viewing axis which
leads to azimuthal distribution of the scattered X-ray photons to provide information on polarisation. Polarised X-rays, incident
on the scatterer through the collimator, will produce a variable azimuthal distribution in the count rate as opposed to uniform
azimuthal distribution of count rate for unpolarised X-rays and detector background. POLIX has four independent detectors, each
with its own front end and processing electronics. Localization of the X-ray photons in the detectors is done by the method of
charge division in a set of resistive anode wires connected in series. |