Influence of $\gamma$-Radiation Dose Growth and Dose Rates on Luminescence Properties of Pure Silica Core Fibers with High-OH Group Content

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Luminescence properties of pure silica core optical fibers (OFs) with a high-OH group content are studied in the visible region at different doses and dose rates of 60Co $\gamma$-radiation. It is shown that the $\gamma$-induced light emission (GLE) spectra consist of Cherenkov emission along the luminescence bands. Different increase rates of the luminescence bands at 450 and 650 nm and the absorption band at 610 nm with increasing $\gamma$-radiation dose are observed. The 450 nm luminescence band is caused by the recombination of holes with the trapped electrons of $E'$-centers. The dose dependence of the 650 nm luminescence band, caused by the nonbridging oxygen hole center (NBOHC), does not coincide with that of the 610 nm absorption band related to this center. It is shown that a considerable part of NBOHC participates in nonradiative relaxation. Also, there is an absorption band caused by color centers different from NBOHC, that contributes to the formation of the 610 nm absorption band. A linear dependence of GLE intensity (at wavelengths of 450 and 650 nm) on the dose rate increase is observed. Such a dependence is caused by a substantial increase in the Cherenkov emission intensity and comparatively small increases in luminescence band intensities at 450 and 650 nm.
2011-01-25