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Observation of strong thermally transferred optically stimulated luminescence (TT-OSL) in BeO
摘要： This work reports the observation of strong thermally transferred optically stimulated luminescence (TT-OSL) signal of BeO OSL ceramic detectors. If the detector is irradiated and the OSL signal is measured for a prolonged time (bleached), subsequent OSL measurements result in zero signal. If the same detector, however, is heated to temperatures in the 225 – 335 °C range (at 5 °C/s), subsequent OSL measurements at room temperature result in an intense signal, even without additional irradiation. The TT-OSL is maximum for a pre-heating to 275 °C (if heated linearly at 5 °C/s), reaching a value of 56 % of the original OSL signal. Both OSL and TT-OSL are reproducible (~3 % standard deviation) and linear with dose over the dose range investigated (up to 100 mGy). The shape of the OSL and TT-OSL curves are essentially identical. A possible explanation for this phenomenon is the thermally stimulated transfer of trapped charges from optically inactive traps to optically active traps responsible for the OSL signal. Correlation between the OSL, TT-OSL and the thermoluminescence (TL) peaks suggests the trapping centers associated with the TL peak at ~310 °C/s (at 5 °C/s) as the source of the trapped charges. These results have implication for the re-estimation of the OSL signal in BeO detectors accidentally exposed to light. Not only they provide further evidence that the material is not completely reset simply by bleaching (optical stimulation), but open a new line of investigation into the underlying TL/OSL mechanisms in BeO.
关键词： thermoluminescence,optically stimulated luminescence,BeO,thermally transferred optically stimulated luminescence,luminescence dosimetry,recuperation
更新于2025-09-23 15:23:52
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Development of a 2D dosimeter using the optically stimulated luminescence of NaMgF3:Eu with CCD camera readout
摘要： A two-dimensional (2D) dosimeter has been developed using tissue-equivalent NaMgF3:Eu as a radiation-sensing material. The bulk compound shows optically stimulated luminescence (OSL) after irradiation in the form of 359 nm Eu2+ emission and where the OSL stimulation occurs at wavelengths above 400 nm. The OSL integrated intensity is shown to be linear up to at least 100 Gy when stimulated with 445 nm light. When the OSL is detected using a thermoelectrically cooled CCD camera, 2D X-ray images can be obtained and the measured intensity is proportional to the total radiation dose. NaMgF3:Eu can be incorporated into epoxy to produce imaging films and both the bulk compound and a film are characterised using the 2D setup. The noise equivalent dose in 2D for the film is determined to be 14 mGy. The modulation transfer function (MTF) is determined and the spatial resolution at MTF = 0.2 is 2.9 lp/mm for the bulk material and 1.25 lp/mm for the film. Our results show that NaMgF3:Eu has potential in the field of 2D dosimetry, where the response to radiation is linear to high doses, sensitive to low doses, and doses can be resolved with a spatial resolution below 1 mm.
关键词： fluoroperovskite,optically stimulated luminescence,dosimetry,NaMgF3
更新于2025-09-23 15:23:52
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Lanthanide-doped MgO: A case study on how to design new phosphors for dosimetry with tailored luminescent properties
摘要： In this work we systematically investigated undoped and lanthanide(Ln)-doped MgO with diverse dopant combinations, MgO:Ce,Ln and MgO:Tb,Ln, where Ln=Eu, Yb, Tm, Sm, Dy, Nd, as well as the same combinations with an additional 3 mol% Li dopant. We characterized the thermoluminescence (TL), optically stimulated luminescence (OSL), radioluminescence (RL), TL emission spectra and OSL emission spectra. Our investigation indicates that Ce3+ and Tb3+ act as recombination centers and their characteristic spectra are observed under thermal or optical stimulation. Conversely, TL measurements suggests that Sm3+, Tm3+ and Yb3+ probably act as electrons traps. The role of Li was investigated, since it was found to increase the RL, TL and OSL intensities in MgO. As part of the present investigation, we identified promising OSL materials sensitive to ionizing irradiation with distinct luminescent properties.
关键词： Optically stimulated luminescence,Dosimetry,Thermoluminescence,Lanthanides
更新于2025-09-19 17:15:36
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Evaluation of a real-time optically stimulated luminescence beryllium oxide (BeO) fibre-coupled dosimetry system with a superficial 140?kVp X-ray beam
摘要： The purpose of this study was to investigate the potential of real-time optically stimulated luminescence (rtOSL) measurements of a beryllium oxide (BeO) ceramic fibre-coupled luminescence dosimetry system. By pulsing the stimulation laser during the exposure to ionizing radiation, an rtOSL dose-rate measurement can be obtained which could be stem effect free. A portable rtOSL BeO ceramic fibre-coupled dosimetry system is presented and characterized using a constant dose-rate superficial 140 kVp X-ray beam. The rtOSL was measured for dose-rates between 0.29 and 3.88 Gy/min, controlled by varying the source to surface distance. After correcting for OSL decay during the exposure, a linear dose-rate response of the change in rtOSL (ΔrtOSL) was observed. The ΔrtOSL was also observed to be stem effect free.
关键词： Optically stimulated luminescence,Fibre-coupled luminescence dosimetry,BeO ceramic,Stem effect
更新于2025-09-12 10:27:22