Optical absorption and thermoluminescence studies in 100 MeV swift heavy ion irradiated CaF2 crystals

Pure and Ytterbium (Yb) doped Calcium fluoride (CaF2) single crystals were irradiated with 100 MeV Ni7+ ions for fluences in the range 5 x 10(11)-2.5 x 10(13) ions cm(-2). The irradiated crystals were characterized by Optical absorption (OA) and Thermoluminescence (TL) techniques. The OA spectra of ion irradiated pure CaF2 crystals showed a broad absorption with peak at similar to 556 nm and a weak one at similar to 220 nm, whereas the Yb doped crystals showed two strong absorption bands at similar to 300 and 550 nm. From the study of OA spectra, the defect centers responsible for the absorption were identified. TL measurements of Ni7+ ion irradiated pure CaF2 samples indicated a strong TL glow with peak at similar to 510 K. However, the Yb doped crystals showed two TL glows at similar to 406 and 496 K. The OA and TL intensity were found to increase with increase of ion fluence upto 1 x 10(13) ions cm(-2) and thereafter it decreased with further increase of fluence. The results obtained are discussed in detail. (C) 2010 Elsevier B.V. All rights reserved.