Gamma Ray Dosimetric Properties of Tb- and Dy-doped Ba 0.88 Sr 0.12 SO 4 Phosphor
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RESEARCH PAPER
Gamma Ray Dosimetric Properties of Tb- and Dy-doped Ba0.88Sr0.12SO4 Phosphor Kh. Rezaee Ebrahim Saraee1 • M. Lotfi1 Received: 29 March 2020 / Accepted: 16 July 2020 Ó Shiraz University 2020
Abstract The chemical co-precipitation method was used to prepare Ba0.88Sr0.12SO4:Dy1.5mol%,Tb1mol% nanocrystalline powder. Ba0.88Sr0.12SO4:Dy1.5mol%,Tb1mol% pellets were fabricated in order to measure gamma ray irradiation. A main TL glow peak around 207 °C, a small peak at 157 °C and a good linear response for doses in the range of 0.01–5 kGy were observed. The TLE spectra of the pellets were recorded at 207 °C. The results of energy response showed that these pellets are energy dependent. The pellets showed fading about 18% during 4 weeks of storage time. The effect of different heating rates on the TL glow peaks of prepared pellets which were recorded after a gamma exposure of 5 kGy was investigated. The intensity of TL glow curves was decreased by an increase in heating rate from 2 °C/s up to 6 °C/s. The dosimetric results showed that the Ba0.88Sr0.12SO4:Dy1.5mol%,Tb1mol% pellets could be useful for monitoring gamma radiation for accidental dose assessment. Keywords Thermoluminescence Dosimetry Gamma ray Phosphor
1 Introduction Barium strontium sulfate is a very good host to develop dosimetric material. Barium strontium sulfates normally are doped with different rare earth elements and other ions and are used as phosphor material in dosimetry applications (Sharaf et al. 2014; Choubey et al. 2011; Aboelezz et al. 2015). If they are used as a dosimetric phosphor, they must have properties such as high sensitivity and linear dose response. The main peak of the TL glow curve must not be at too high or low temperatures due to instrumental problems and the fading effect. Moreover, the energy response must be independent of the energy of radiation. Usually, there are not all of the ideal dosimetry properties in one TL material. When these phosphors are exposed to gamma rays or other ionizing radiation, they absorb a fraction of the radiation energy and store as trapped electrons and holes at defect sites in the phosphors. Defect sites are those inherently present in the phosphors or those are & Kh. Rezaee Ebrahim Saraee [email protected] 1
Faculty of Physics, University of Isfahan, Isfahan 81746-73441, Iran
produced by doping the sample with impurities such as rare earth elements. By thermal or optical energy source, the electrons and holes can be released from the traps. It means the stored energy at the trap centers can be released as visible light due to the recombination of trapped carriers in luminescence centers (Tamrakar and Bisen 2015). Many studies have investigated barium and strontium sulfate nanophosphor compositions for applications as dosimeters in a given range of doses (Rezaee Ebrahim Saraee and Aghay Kharieky 2013; Rezaee Ebrahim Saraee et al. 2013, 2014; Samariha and Rezaee Ebrahim Saraee 2018). Moreover, the dosimetric properties of Dy- an
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