Real-time luminescence from Al2O3 fiber dosimeters (original) (raw)
Related papers
Effect of high-dose irradiation on the optically stimulated luminescence of Al2O3:C
Radiation Measurements, 2004
This paper examines the e ect of high-dose irradiation on the optically stimulated luminescence (OSL) of Al2O3:C, principally on the shape of the OSL decay curve and on the OSL sensitivity. The e ect of the degree of deep trap ÿlling on the OSL was also studied by monitoring the sensitivity changes after doses of beta irradiation and after step-annealing of samples previously irradiated with high doses. The OSL response to dose shows a linear-supralinear-saturation behavior, with a decrease in the response for doses higher than those required for saturation. This behavior correlates with the sensitivity changes observed in the samples annealed only to 773 K, which show sensitization for doses up to 20-50 Gy and desensitization for higher doses. Data from the step-annealing study leads to the suggestion that the sensitization is caused by the ÿlling of deep electron traps, which become thermally unstable at 1100-1200 K, whereas the desensitization is caused by the ÿlling of deep hole traps, which become thermally unstable at 800-875 K, along with a concomitant decrease in the concentration of recombination centers (F + -centers). Changes in the shape of the OSL decay curves are also observed at high doses, the decay becoming faster as the dose increases. These changes in the OSL decay curves are discussed in terms of multiple overlapping components, each characterized by di erent photoionization cross-sections. However, using numerical solutions of the rate equations for a simple model consisting of a main trap and a recombination center, it is shown that the kinetics of OSL process may also be partially responsible for the changes in the OSL curves at high doses in Al2O3:C. Finally, the implication of these results for the dosimetry of heavy charged particles is discussed.
Radiation Measurements, 2003
Al2O3 single crystals were grown by the laser heated pedestal growth (LHPG) technique for potential use in radiation dosimetry using optically stimulated luminescence. The crystals were grown in the form of short single crystal ÿbers under a variety of growth conditions. Thermoluminescence (TL), radioluminescence (RL), cathodoluminescence, photoluminescence and optically stimulated luminescence (OSL) measurements were carried out on all ÿbers to assess their potential in luminescence radiation dosimetry. Measurements of luminescence spectra and the TL and OSL dose response characteristics lead to the suggestion that LHPG ÿbers have attractive luminescence dosimetry properties and warrant further study for potential applications in radiotherapy using OSL.
Optically stimulated luminescence of Al2O3
Radiation Measurements, 1998
The optically stimulated luminescence (OSL) technique has already become a successful commercial tool in personal radiation dosimetry, medical dosimetry, diagnostic imaging, geological and archeological dating. This review briefly describes the history and fundamental principles of OSL materials, methods and instrumentation. The advantages of OSL technology and instrumentation in comparison with thermoluminescent technique are analyzed. Progress in material and detector engineering has allowed new and promising developments regarding OSL applications in the medical field. Special attention is dedicated to Al 2 O 3 :C as a material of choice for many dosimetric applications. Different aspects of OSL theory, materials optical and dosimetric properties, instrumentation, and data processing algorithms are described. The next technological breakthrough was done with Fluorescent Nuclear Track Detectors (FNTD) that have some important advantages in measuring fast neutron and high energy heavy charge particles that have become the latest tool in radiation therapy. New Mg-doped aluminum oxide crystals and novel type of imaging instrumentation for FNTD technology are discussed with regard to application in mixed neutron-gamma fields, medical dosimetry and radiobiological research.
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.
Development of a 2D dosimetry system based on the optically stimulated luminescence of Al2O3
Radiation Measurements, 2014
h i g h l i g h t s A 2D dosimetry system based on OSL of Al 2 O 3 was built and demonstrated. Combination of UV and F-center emission is used for fast readout. A special algorithm was developed to correct for slow F-center emission. Potential of measuring 2D dose was demonstrated. Comparison of dose profile with EBT2 and EDR2 film showed good qualitative agreement.
Comparison between blue and green stimulated luminescence of Al2O3:C
Radiation Measurements, 2010
This paper presents a systematic comparison of OSL signals from Al 2 O 3 :C when stimulated with blue and green light. Al 2 O 3 :C detectors were irradiated with various doses and submitted to various bleaching regimes using yellow, green and blue light. Most of the investigations were carried out using LuxelÔtype detectors used in the commercial LuxelÔ and InLightÔ dosimetry systems (Landauer Inc.). Al 2 O 3 :C single crystals and Al 2 O 3 :C powder were also used to complement the investigations. The results show that, although blue stimulation provides faster readout times (OSL curves that decayed faster) and higher initial OSL intensity than green stimulation, blue stimulation introduced complicating factors. These include incomplete bleaching of the dosimetric trap when the Al 2 O 3 :C detectors are bleached with yellow or green light and the OSL is recorded with blue light stimulation, and an increased residual level due to stimulation of charge carriers from deep traps. The results warrant caution when using blue stimulation to measure the OSL signal from Al 2 O 3 :C detectors, particularly if the doses involved are low and the detectors have been previously exposed to high doses.