Optically and Thermally Stimulated Luminescence in X-Ray Irradiated Sno-Doped Sro-B2O3 and ZnO-P2O3 Glasses for Passive-Type Dosimeter

Abstract

Optically and thermally stimulated luminescence (OSL and TSL) phenomenon is based on the presence of electron and/or hole traps and luminescence centers in storage phosphor materials. During exposure to ionizing radiation such as x-ray, γ-ray and β-ray, the traps are occupied with charged carriers such as electrons and holes that are created by irradiation with ionizing radiation. De-trapping of these carriers requires energy. The energy is provided by stimulating of the phosphor materials with visible or infrared light (OSL) or by heating of the phosphor (TSL). During a de-trapping transition, free carriers created by the absorption of photons from the stimulating radiation field, recombine with the luminescence centers, whereby visible photons are emitted. Since the OSL or TSL intensity is in the most cases proportional to absorbed dose of ionizing radiation, the phosphor materials which exhibit the OSL and TSL phenomena adapt to two-dimensional imaging sensor for ionizing radiation. Although imaging plate (IP) using photostimulable phosphor materials such as BaFBr:Eu [1,2] and CsBr:Eu [3] can be now used as two-dimensional sensor for ionizing radiation, these phosphor materials with deliquescent property exhibit poor fading characteristics which is one problem on two dimensional radiation dose estimation using the IP. As a result of surveying many possible phosphor materials, we found that SnO-doped SrO-B2O3 and ZnO-P2O3 glass without deliquescent properties exhibit an efficient OSL and TSL, and good fading characteristics. Typical OSL stimulation and emission spectra of x-ray irradiated SnO-doped SrO-B2O3 glass are shown in Fig.1. In this work, the OSL and TSL characteristics in x-ray irradiated SrO-B2O3 and ZnO-P2O3glasses are in the first time reported and OSL and TSL characteristics are discussed for the passive type dosimeter. Ref. [1] K.Takahashi et al., J. Electrochemcal Soc., 32(1985) 1492.[2] M.Takebe and K.Abe, Nuclear Instruments and Methods, A345(1994) 606.[3]H.Nanto et al., Nuclear Instruments and Methods, A580 (2007)278. Figure 1