X-ray polarimetric measurements in xenon gas filled detectors

In this work we present a Monte Carlo and experimental study of the electron clouds produced by photoionization events in xenon when linearly-polarized x-rays are absorbed in the gas. Photoelectric effect is sensitive to polarization, since the angular distributions for photoelectron emission tend to align with the polarization vector, and the profiles of the electron clouds produced in the gas will keep memory of the effect. The present Monte Carlo simulations examine this effect for x-ray energies up to 50 keV, reproducing the photoionization events for linearly-polarized photons and following all electrons individually in the gas until the electron cloud is fully grown. In addition, we report experimental measurements obtained with a Xe-filled Gridded Microstrip Gas Chamber for a group of linearly-polarized x-ray lines below 15 keV. The measured energy spectra were found to bring about indirect but clear evidence of the same effect.