Radiation hard humidity sensors for high energy physics applications using polymide-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 applications and in particular in the experiments actually running at the European Organization for Nuclear Research (CERN). On this line of argument, due to the wide investigations carried out in the last years aimed to assess the radiation hardness capability of fiber optic technology in high energy physics environments, our multidisciplinary research group has been recently engaged in the development and assessment of fiber optic sensors based on polyimide-coated Fiber Bragg Gratings (FBGs) to perform relative humidity (RH) monitoring at temperatures below 0 degrees C as well as in presence of strong ionizing radiations. Data here reported, obtained during a deep experimental campaign carried out in the laboratories of CERN, demonstrate the amazing RH sensing properties of such sensors in the temperature range -15-20 degrees C as well as their radiation hardness capability up to (at least) 10kGy dose of ionizing radiations.