Optical absorption and thermoluminescence studies in 100 MeV swift heavy ion irradiated CaF_2 crystals

摘要

Pure and Ytterbium (Yb) doped Calcium fluoride (CaF_2) single crystals were irradiated with 100 MeV Ni ions for fluences in the range 5 x l0~(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 CaF_2 crystals showed a broad absorption with peak at ~556 nm and a weak one at ~220 nm, whereas the Yb doped crystals showed two strong absorption bands at ~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 CaF_2 samples indicated a strong TL glow with peak at ~510 K. However, the Yb doped crystals showed two TL glows at ~406 and 496 K. The OA and TL intensity were found to increase with increase of ion fluence upto 1 ×10~(13) ions cm~(-2) and thereafter it decreased with further increase of flu-ence. The results obtained are discussed in detail.