Scintillating materials are widely used in detection systems addressing different fields: medical imaging, homeland security, high energy physics calorimetry, industrial control, and oil drilling exploration. These ionizing radiations are photons or particles such as gamma, X-ray, alpha, beta particles. While technology to detect gamma and X-rays is mature and commercially available, alpha and beta particles are trickier to detect due to their short mean free path in the matter including gas. In the case of beta it can range from a few tens of micrometres up to over centimetres in gas. They can thus hardly be detected from far as it is done for gamma rays. When their energy is reduced, their detection becomes critical because they must be almost in contact with the sensor. Beyond detecting the radioactive elements, metrology requires to quantify their activity, what involves modelling of the matter radiation. For most of the beta-active critical elements, there is no reliable and widely deployable technology.
In environmental laboratories liquid scintillation counting (LS) is the gold standard to measure radioactive liquids and H-3 in gas. In the case of gas analysis, it is bubbled in a solution containing an aromatic solvent and a fluorophore, what generates significant organic pollution, requires to mix gas and liquids, and takes about a week. On-site measurements for some isotopes use sophisticated technologies which cannot be widely deployed.
SPARTE aims to propose a breakthrough solution based on highly efficient porous scintillators enabling the detection and quantification of several critical radioactive rare gas isotopes of primary importance. The proposed materials are based on 3 different approaches: aerogels of inorganic nano-scintillator, aerogel of metal-organic-frameworks (MOF) showing an intrinsic porosity and crystal of MOF. The targeted isotopes are Kr-85, Xe-133, H-3, and potentially Ar-37.
Porous scintillators were produced and tested. The goal of online detection is achieved, with a detection efficiency of 17% for H-3 and nearly 100% for Kr-85 over an acquisition time of 100 seconds. Excellent linearity was observed, and an innovative approach enabling the measurement of gas mixtures is defined. A new measurement method for metrology purposes was developed, and a prototype of compact detector incorporating only 2 PMTs was produced and tested, allowing the detection of H-3 with 8% sensitivity.
