Radiation defects in BaF$_2$-Cd

Radiation defects in barium fluoride single crystals doped with cadmium have been investigated by luminescence and absorption spectroscopy, as well as by electron spin resonance spectroscopy. Three types of Cd$^+$ centers differing by the local environment with the point symmetries O$_h$, C$_3$$_v$ and C$_2$$_v$ have been identified although in the crystals only the cubic centers are usually formed. We believe that these features may arise from the difference in the spacial distribution of the impurities in the crystals.