Radiation resistance diagnostics of wide-gap optical materials

•Novel luminescent approach of the detection of radiation damage was demonstrated.•Cathodoluminescence is analysed within a thin proton-irradiated crystal layer.•Radiation defects are exhibited via typical emission and influence on the exciton one.•High radiation tolerance of MgO and Al2O3 crystals was confirmed.

Novel approach in the detection of radiation damage created by ion beams in optical materials was demonstrated. Protons of the energy of 100 keV and fluence of 1017 cm−2 create sufficient amount of crystal lattice defects in the thin surface layer for testing of optical materials needed for future fusion reactors. These structural defects can be detected and analysed using the spectra of cathodoluminescence excited in the irradiated layer by an electron beam with adjustable energy. The method was verified by the enhanced intensity of F-type luminescence that reflects the creation of radiation-induced oxygen vacancies in MgO and Al2O3 crystals. Low radiation resistance of nominally pure (Lu1-xGdx)2SiO5 crystals was demonstrated by almost total suppression of intrinsic luminescence after the same irradiation.