Proton Bragg peak imaging by colour centre radiophotoluminescence in lithium fluoride thin film radiation detectors on silicon

Abstract Optically transparent lithium fluoride (LiF) thin films, thermally evaporated on Si(100) substrates, are under investigation as novel radiation detectors based radiophotoluminescence for imaging of the full Bragg curves proton beams produced by a linear accelerator therapy development at ENEA C.R. Frascati. Proton irradiation induces formation stable colour centres in LiF, amongst which broadband light-emitting F 2 and 3 + aggregate defects, whose concentrations locally proportional to energy deposited material. Their spatial distributions irradiated LiF films crystals carefully measured acquiring latent two-dimensional visible fluorescence images with an optical microscope blue lamp excitation. Several grown silicon substrate were air increasing energies up 35 MeV their surface parallel particle beam cleaved edge perpendicularly facing it; each sample, image acquired from top side film allows obtain depth profile released protons. Differences centre detected respect presented discussed. Accurate Monte Carlo simulations allow fully explain experimental behaviours, paving way towards using advanced diagnostics typical used therapy.