Measurement of the electron yield of CsI with polarized x rays

Astronomical X-ray polarimetry based on photoelectric effect with microgap detectors

“…In x-ray polarimetry this achievement has been impossible as no significant modulation with polarisation has yet been obtained with photoelectric devices and the two techniques (Bragg and Compton) used so far are overwhelmed by low efficiency and high background, respectively. Attempts to carry out photoelectric polarimetry have been unsuccessful because of the low modulation or the high systematic effects [4], [5]. In this paper we show the results of testing very high resolution detectors as photoelectric polarimeters.…”

“…For example, 8-keV electrons are ejected maximally at about 75 o with respect to the incoming photon direction. Due to the angular dependence on M, the photoelectric effect (5) ,…”

“…Starting from this point many workers have tried to conceive or develop polarimeters based on the distribution of (5). The main limitation to this technique is that at the energies of interest electrons propagate in the matter less than photons.…”

“…This design has been very popular since some measurements [19] suggested that low-energy electrons emitted from a cathode could retain more memory of the polarisation than expected from current theories of collision. Further measurements have significantly reduced this effect [5]. Some measurements have also been made with thin targets by collecting energetic photoelectrons with high electric fields.…”

General History of X-Ray Polarimetry in Astrophysics

“…Notwithstanding a relatively poor modulation factor of the order of 25%, the full exploitation of the optics at low energies and the condition to be background-less down to very weak sources, promised an estimated sensitivity that would enable polarimetry of extragalactic sources. Further measurements showed that the actual modulation was much lower [14] and this photoelectric polarimeter was no more adopted. But this showed to the small community interested on this topic how relevant would be the implementation of a photoelectric imaging device for the focal plane.…”