Rare-earth doped silica-based scintillating fibers for ionizing radiation sensing

Scintillating optical fibres based on rare-earth (RE) doped silica glass are presently considered as ionizing radiation sensors. They can find applications in numerous fields in which a real time radiation measurement, even very distant from the radiation field (remote monitoring) is required. To this scope, the incorporation features of RE ions in sol-gel silica are investigated. Structural and vibrational studies, coupled to optical investigations, allow to find the most suitable RE concentrations and synthesis parameters for optimizing scintillation efficiency and RE dispersion, avoiding the formation of aggregates. Nano-aggregates are indeed formed for RE concentrations exceeding 1 mol%. Amorphous clusters are detected for Gd, Tb, and Yb doping. Moreover, cluster formation is sensitive to glass sintering conditions: amorphous Ce-based clusters or CeO2 nano-crystals are formed for reducing or oxidizing sintering atmosphere, respectively. Crystalline and highly luminescent Eu2Si2O7 nano-aggregates are found in SiO2:Eu [1]. After the description of advantages and challenges for the use of optical fibre based dosimeters during medical radiation therapy and diagnostic irradiations, recent results obtained by using Ce, Eu, and Yb doped optical fibres are described [2]. Finally, the perspectives and open problems for the employment of silica fibres in high energy physics detectors are also discussed [3]. 1. A. Baraldi et al., J. Phys. Chem. C 117, 26831 (2013) 2. I. Veronese et al., Appl. Phys. Lett. 105, 061103 (2014) 3. F. Cova et al, Opt. Lett. 43 (4), 903 (2018)