  The polarisation of x-ray photons can be determined by measuring the
direction of emission of a K-shell photoelectron. Effective exploitation of
this effect below 10 keV would allow development of a highly sensitive x-ray
polarimeter dedicated in particular to x-ray astronomy observations. Only with
the advent of finely segmented gas detectors was it possible to detect
polarisation sensitivity based on the photoelectric effect in this energy
range. Simulation and measurements at 5.4 and 8.04 keV with a microgap gas
counter, using both a polarised and an unpolarised x-ray source, showed that
the photoelectron track in a neon-based gas mixture retains the memory of the
polarisation of the incoming photons. Possible experiments aimed at
galactic/extragalactic sources and solar flares are considered and their
sensitivity to these sources is calculated.
