Refractive index changes and nuclear activation upon irradiation of lithium niobate crystals with different low-mass,high-energy ions

Refractive index changes (Delta n) in lithium niobate crystals upon irradiation with high-energy protons, deuterons, (^3) He, and (^4alpha ) particles (up to 14 MeV/nucleon) are created, and the accompanying, unwanted nuclear activation is investigated. The measurements give answers to the question which ion is the best choice depending on the requirements: largest values of (Delta n) are achieved with (^4alpha ) particles, low nuclear activation with deuterons, or the best tradeoff between (Delta n) and activation with (^3) He, respectively.