Cathodoluminescence of synthetic zircon implanted by He⁺ ion

He⁺ ion implantation at 4.0 MeV, equivalent to energy of α particles from natural radioactive nuclei ²³⁸U and ²³²Th, has been conducted for undoped synthetic zircon. The cathodoluminescence (CL) of implanted samples was measured to clarify the radiation-induced effects. Unimplanted synthetic zircon shows pronounced and multiple blue emission bands between 310 nm and 380 nm, whereas the implanted samples have an intense yellow band at ~550 nm. The blue emission bands can be assigned to intrinsic defect centers formed during crystal growth. The yellow band should be derived from induced-defect centers by He⁺ ion implantation, which might be related to the metamicitization originated from a self-induced radiation in natural zircon. The yellow band may be separated into two emission components at 1.96 eV and 2.16 eV. The emission component at 2.16 eV is recognized in both unimplanted and implanted samples, and its intensity increases with an increase in the implantation dose. The CL of zircon can be used as the geodosimeter.