RADIATION-INDUCED COLOR-CENTERS IN CERIUM FLUORIDE

Radiation induced colour centres in CeF3 crystals have been studied by spectroscopic techniques using eight crystals produced with various d egrees of purity by different manufacturers in slightly different grow ing conditions. The crystals were irradiated at liquid nitrogen temper ature with electrons of 7 MeV at doses of 10(4) to 3 . 10(6) rad. Abso rption spectra ranging between 250 and 750 nm recorded at irradiation temperature are quite different from one producer to another, regardin g both the values of absorption coefficient (17 cm(-1) -5 cm(-1)) and the number and form of the absorption bands. Step-by-step annealing up to room temperature produces new absorption bands. in the range of 20 0-240 K, three well resolved bands appear as in the case of crystals i rradiated at room temperature.