EPR investigation of defects in Bi12GeO20:Cr single crystal irradiated by high energy uranium ions

The results of investigations of EPR spectra of chromium doped $Bi_{12} GeO_{20} (BGO)$ single crystals are presented. The crystals were studied before and after irradiation by the ${}^{235}U$ ions with energy 9.47 MeV/u and fluency $5\cdot {10}^{2}c{m}^{-2}$. The effect of heating irradiated samples in air on the EPR spectra is also studied.