Radiation induced formation of color centers in PbWO4 single crystals

The changes in the absorption spectra induced by ${\mathrm{Co}}^{\mathrm{60}}$ irradiation and high temperature annealing was studied for selected ${\mathrm{PbWO}}_{\mathrm{4}}$ crystals. Based on radiation and annealings induced absorption spectra, four color centers are proposed, which could be responsible for shaping the absorption spectrum of ${\mathrm{PbWO}}_{\mathrm{4}}$ crystals below 3.6 eV, namely ${\mathrm{Pb}}^{\mathrm{3+}},$ ${\mathrm{O}}^{\mathrm{-}},$ F, and ${\mathrm{F}}^{\mathrm{+}}$ centers. Thermoluminescence (TSL) glow curves above room temperature were also studied on these samples to determine further the trap levels resulting from irradiation. Correlation between the results obtained by TSL and ${\mathrm{Co}}^{\mathrm{60}}$ irradiation induced absorption changes is discussed.