Radiation hard humidity sensors for high energy physics applications using polyimide-coated fiber Bragg gratings sensors

This work is devoted to a feasibility analysis for the development of fiber optic humidity sensors to be applied in high-energy physics (HEP) applications and in particular in experiments actually running at the European Organization for Nuclear Research (CERN). Due to the stringent sensors requirements concerning radiation hardness capability and low temperature operation, we focus our attention on the investigation of fiber optic humidity sensors based on polyimide-coated fiber Bragg gratings (FBG). Data here reported, obtained during a wide experimental campaign carried out in the laboratories of CERN, demonstrate that the selected technological platform is able to perform relative humidity (RH) measurements with percent resolution in the temperature range −15 to 20 °C as well as in presence of ionizing radiations up to 10 kGy, largely outperforming conventional humidity sensors, currently employed within CERN environment.