Effect of high-dose irradiation on the optically stimulated luminescence of Al2O3:C (original) (raw)
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Dose-Dependence of Trap Parameters of OSL Decay from Al<sub>2</sub>O<sub>3</sub>:C
World Journal of Nuclear Science and Technology, 2012
Optically Stimulated Luminescence (OSL) trap parameters can only be reliably determined through the detailed analysis of OSL decay curves. In this study the kinetic parameters of a blue-light stimulated luminescence (BLS) decay curve from Al 2 O 3 :C sample irradiated at 0.1, 0.15, 0.2, 0.4 and 0.6 Gy beta doses were obtained using the same basic methods with some modifications applied and also by using our suggestion: Active-OSL Approximation (AOSL). The results were compared with those of other studies on the trap parameters of Al 2 O 3 :C material.
A quantitative kinetic model for Al2O3:C: TL response to ionizing radiation
Radiation Measurements, 2007
This paper presents a quantitative kinetic model for the important dosimetric material Al 2 O 3 :C. The model consists of two traps and two centers, and reproduces the experimental thermoluminescence (TL) vs. dose behavior, as well as the experimental variation of the optical absorption coefficient K with beta dose. Initial estimates of the kinetic parameters in the model are obtained either from published experimental data, or by using reasonable physical assumptions. Good agreement between the experimental data and calculations from the model are obtained for three different types of samples of alumina. This is achieved by keeping the trapping and recombination probabilities constant for all three samples, while the concentrations of the carriers are varied. The kinetic model provides also a quantitative description of the experimentally observed nonmonotonic behavior of the TL dose-response curves for all three samples.
Radiation Measurements, 2004
The thermoluminescence (TL) and optically stimulated luminescence (OSL) response of Al2O3 dosimeters to high-energy heavy charged particles (HCP) has been studied using the heavy ion medical accelarator at Chiba, Japan. The samples were Al2O3 single-crystal chips, of the type usually known as TLD-500, and Luxel TM dosimeters (Al2O3:C powder in plastic) from Landauer Inc. The samples were exposed to 4 He (150 MeV=u), 12 C (400 MeV=u), 28 Si (490 MeV=u) and 56 Fe (500 MeV=u) ions, with linear energy transfer values covering the range from 2.26 to 189 keV= m in water and doses from 1 to 100 mGy (to water). A 90 Sr= 90 Y beta source, calibrated against a 60 Co secondary standard, was used for calibration purposes. For OSL, we used both continuous-wave OSL measurements (CW-OSL, using green light stimulation at 525 nm) and pulsed OSL measurements (POSL, using 532 nm stimulation from a Nd:YAG Q-switched laser). The e ciencies (ÁHCP; ) of the di erent HCPs at producing OSL or TL were observed to depend not only upon the linear energy transfer (LET) of the HCP, but also upon the sample type (single crystal chip or Luxel TM ) and the luminescence method used to deÿne the signal-i.e. TL, CW-OSL initial intensity, CW-OSL total area, or POSL. Observed changes in shape of the decay curve lead to potential methods for extracting LET information of unknown radiation ÿelds. A discussion of the results is given, including the potential use of OSL from Al2O3 in the areas of space radiation dosimetry and radiation oncology.
Journal of Applied Physics, 2006
Nonmonotonic dose dependence of optically stimulated luminescence ͑OSL͒ has been reported in a number of materials including Al 2 O 3 : C which is one of the main dosimetric materials. In a recent work, the nonmonotonic effect has been shown to result, under certain circumstances, from the competition either during excitation or during readout between trapping states or recombination centers. In the present work, we report on a study of the effect in a more concrete framework of two trapping states and two kinds of recombination centers involved in the luminescence processes in Al 2 O 3 : C. Using sets of trapping parameters, based on available experimental data, previously utilized to explain the nonmonotonic dose dependence of thermoluminescence including nonzero initial occupancies of recombination centers ͑F + centers͒, the OSL along with the occupancies of the relevant traps and centers are simulated numerically. The connection between these different resulting quantities is discussed, giving a better insight as to the ranges of the increase and decrease of the integral OSL as a function of dose, as well as the constant equilibrium value occurring at high doses.
Dose-dependent change in the optically stimulated luminescence decay of Al2O3:C
Radiation Measurements, 2009
Al 2 O 3 :C is an established thermoluminescence (TL)/optically stimulated luminescence (OSL) dosemeter for personnel, space and medical applications. Mathematically, the decay of Al 2 O 3 :C OSL can be described by a sum of three exponentials, termed as fast, medium and slow components. The shape of the OSL decay of Al 2 O 3 :C is known to be dose dependent. This contribution explores this observation and provides a simple explanation for the dose-dependent OSL decay shape using the differences in the dose response of the individual components. The growth of these components with radiation dose is different such that the fast component grows linearly up to 300 Gy and the medium and slow components saturate at w20 Gy. Further, the shape of the OSL decay from an alpha-irradiated sample is similar to a sample irradiated to high beta doses. Component-specific alpha efficiency shows that the fast component has higher alpha efficiency as compared to the medium and the slow components.
Influence of the irradiation temperature on TL sensitivity of Al2O3:C
Radiation Measurements, 2001
Al2O3 : C TL/OSL dosemeters were irradiated at di erent temperatures. TL sensitivity was found to decrease by about 40% with decreasing irradiation temperature between +30 and −100 • C. High temperature TL peaks were shown to appear only if the irradiation temperature is higher than 200 • C. Recombination of holes with electrons in the dosimetric traps was proposed as a mechanism to explain these phenomena.
Radiation Measurements, 2004
The thermally and optically stimulated luminescence (TL and OSL) response to high energy heavy-charged particles (HCPs) was investigated for two types of Al2O3:C luminescence dosimeters. The OSL signal was measured in both continuous-wave (CW) and pulsed mode. The e ciencies of the HCPs at producing TL or OSL, relative to gamma radiation, were obtained using four di erent HCPs beams (150 MeV=u 4 He; 400 MeV=u 12 C; 490 MeV=u 28 Si, and 500 MeV=u 56 Fe). The e ciencies were determined as a function of the HCP linear energy transfer (LET). It was observed that the e ciency depends on the type of detector, measurement technique, and the choice of signal. Additionally, it is shown that the shape of the CW-OSL decay curve from Al2O3:C depends on the type of radiation, and, in principle, this can be used to extract information concerning the LET of an unknown radiation ÿeld. The response of the dosimeters to low-LET radiation was also investigated for doses in the range from about 1-1000 Gy. These data were used to explain the di erent e ciency values obtained for the di erent materials and techniques, as well as the LET dependence of the CW-OSL decay curve shape.
TL, OSL, and phototransferred TL in beta-irradiated anion-defective Al2O3
Radiation Measurements, 2004
The behavior of TL, OSL and PTTL under thermal and/or optical stimulation in beta-irradiated-Al2O3 was investigated. The noticeable change of the shape of the main TL peak after thermal or optical stimulation clearly shows that this peak is related to at least two traps. The OSL curves recorded after preheating up to a given increased end temperatures are described by two exponential decays curves. The ÿrst one is associated to the decay of the traps responsible for the main TL peak. The second exponential is related with the phototransfer from the deep to the main traps. A simple model of the OSL process, based on simultaneous reÿlling of shallow traps and their reverse ÿlling due to phototransfer from deep traps, under illumination with light is proposed. The model describes well the obtained experimental data.