Investigation of the Properties of the Heavy Scintillating Fibers for Their Potential Use in Hadron Therapy Monitoring

Recent development in the production of inorganic scintillators resulted in a variety of materials, many of which show excellent timing properties and large light yield. Due to large densities and effective atomic numbers, those materials are well suited for detection of a-few-MeV prompt gamma radiation, which is emitted during hadron therapy. Additionally, when combined with modern silicon photomultipliers (SiPM), they allow compact and granular detector designs. Therefore, heavy scintillators seem to be promising candidates for prompt gamma imaging (PGI) detectors, such as Compton cameras. Under the SiFi-CC (SiPM and Fiber based Compton Camera) project the investigation of heavy scintillating materials for their application in hadron therapy monitoring has been carried out. The study was focused on lutetium based crystals, including LuAG:Ce and LYSO:Ce as well as recently developed GAGG:Ce,Mg. Examined samples had an elongated, fiber-like shape, with 100 mm length and 1 × 1 mm2 square cross section. The following features of such fibers were investigated: attenuation length of the optical photons, light yield, energy resolution and timing characteristics. The study has shown that out of the materials chosen for the study LYSO:Ce is the most promising candidate for applications in PGI. Additionally, in order to optimize performance of scintillators an influence of wrapping was investigated. It has been observed that aluminum wrapping causes an increase in the light yield, but decreases the attenuation length.