Luminescence sensors on the basis of quartz glasses with localization of gamma-radiation source

摘要

Optical fibers as detectors of radiation have a lot of advantages: big length, little diameter, no electrical interference, and an opportunity to measure radiation from the spread source. Optical characteristics of pure silica glasses as a material for optical fibers are very important. Luminescence spectra of high-purity silica glasses made by sol-gel technology have been investigated. Silica glasses are very stable and their characteristics are changed in narrow range. Sol-gel technology was chosen because it allows obtaining samples with different properties during changing technology. In other technologies, uncontrolled admixtures presence leads to big number of luminescence bands appearance. Their analysis is difficult. Luminescence band with energy of 1,9 eV appeared during exposition of glasses to gamma-irradiation. Luminescence intensity dependence on irradiation dose is analyzed. Appearance reasons are investigated. Absorption band with energy 2,0 eV appears in glasses during irradiation due to nonbridging oxygen hole centers (NBOHC : ≡ Si -O ↑). The same centers are responsible for luminescence with 1,9 eV. Energetic diagram is proposed. Principle scheme of gamma-irradiation optical fiber sensor is proposed on the basis of optical fiber made by sol-gel technology. Optical fiber is illuminated from the lightsource with energy of 2,0 eV. Luminescence appears at those portions of optical fiber, which are exposed to gamma irradiation. Such luminescence pulses are registered from both sides of optical fiber. Travel time is proportional to the distance from the end of fiber to irradiated portion. Length of pulse is proportional to the length of portion. Thermal annealing of optical fiber is discussed.