Speaker
Description
Gas Electron Multipliers (GEMs) are crucial for high-resolution X-ray polarimetry, enabling precise measurements in astrophysical missions like IXPE, Polarlight, and the upcoming eXTP telescope. While the IXPE collaboration has refined Gas Pixel Detector (GPD) technology using conventional GEM fabrication methods such as wet-etching and laser drilling, further optimization of hole patterning remains essential. Achieving ideal aspect ratios and minimizing dielectric charging are key to ensuring gain stability and detector uniformity. This work investigates a plasma-based Reactive Ion Etching (RIE) technique at FBK to address these challenges, producing GEMs with more vertical and uniform hole profiles. We introduce a plasma-based GEM geometry with 30 μm diameter holes and a 50 μm pitch, characterized by SEM and PFIB analysis. Collaboration with INFN Pisa and Turin enabled extensive electrical testing and performance validation in GPDs, supported by Garfield++ simulations. Initial results show that plasma-etched GEMs exhibit gain vs. voltage behavior comparable to IXPE currently deployed detectors. While still in early R&D, this fabrication approach holds significant potential to enhance the sensitivity of future space-based X-ray polarimeters, improving measurement accuracy and advancing detector technology. Future work will focus on quantitatively evaluating the performance of plasma-based GEMs relative to conventional ones, particularly in terms of X-ray polarimetry resolution in the keV range.
