Effect of La Doping on Calcium Tungstate (CaWO4) Crystals Radiation Hardness

The induced absorption spectra were measured for equally grown CaWO 4 and CaWO 4 :La single crystals after 60 Co radioisotope irradiation by doses within 1 to 230 Gy. La doping increases considerably the radiation hardness of CaWO 4 material similarly as was observed for isostructural PbWO 4 single crystals recently. Transmission of as grown undoped CaWO 4 shows a noticeable decrease below 450 nm, which gives the evidence of deep trapping states. These trapping centres are effectively diminished by La doping as well. Induced absorption bands are discussed in the light of known and hypothesized color centers in CaWO 4 and PbWO 4 single crystals, which were reported earlier in the literature.

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