Color centers induced in Y3Al5O12 single crystals by swift heavy ions and reactor neutrons

The induced damage in single crystals of yttrium alumina garnet (Y3Al5O12) bombarded at GANIL with 561 MeV 51Cr, 466 MeV 128Te, and 957 MeV 208 Pb ions, and at Algiers with reactor neutrons has been studied by optical measurements. Optical absorption bands centered at 250, 300 and 380 nm are observed after irradiation with ions and neutrons. The variation of the absorption as a function of fluence and electronic stopping power are presented and discussed. Photoluminescence, excited from 380 nm optical absorption band of this garnet is measured at room temperature. The results show the increase of the emission band width with increasing electronic stopping power. The confrontation of the results obtained with ions and neutrons irradiation confirm the contribution of the energetic heavy ions to point defects production. Furthermore, the existence of an electronic stopping power threshold between 10 and 15 keV/nm for oxygen ions displacements is derived.