Effect of pH on lyoluminescence of K 3 Na(SO 4 ) 2 :Eu 3+ phosphor for its application in dosimetry of high-energy radiations (original) (raw)
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Lyoluminescence (LL) of microcrystalline K 3 Na(SO 4) 2 :Eu 3 þ was studied for different doses and for different pH values of solvents. The material was prepared by a simple melt method and was then crushed and sieved to get particle sizes in different ranges between 50-250 mm. K 3 Na(SO 4) 2 :Eu 3 þ (0.1%) phosphor thus obtained was given proper heat treatment (annealed at 800°C for 1 h). It was then irradiated with γ rays from 60 Co radioactive source to study its LL characteristics and the effect of pH of the solvent on LL intensity. The glow (decay) curves, dose response and variation of the LL intensity with pH were studied for different doses (10 Gy-25 kGy). pH of the solutions used for studying LL was varied in the range of 0.55-13.0 using different diluted acids (i.e., H 2 SO 4 , HCl and HNO 3) and alkalies (i.e., LiOH, NaOH and KOH) solutions. The LL intensity was not only found to vary with the net pH of the solution used for taking LL but also with the different acids/alkalies used for varying the pH. This has a great importance in radiation dosimetry using LL as the user needs to know which solution is best suited. The material shows linear dose response for a broad range of doses (10 Gy-10 kGy). It was also observed that the fading of the LL intensity is more if the material is exposed to room light than its storage in dark. Very wide dose range, high-sensitivity and low fading make the material suitable for dosimetry of high-energy radiations using LL technique.
Lyoluminescence (LL) of microcrystalline K 3 Na(SO 4) 2 doped with Eu (0.1 mol%) as an impurity was studied for different doses and for different pH values of solvents. The material was prepared by simple melt method and then crushed and sieved to get particle size between 75-125 µm. K 3 Na(SO 4) 2 :Eu 3+ (0.1%) phosphor thus obtained was given proper heat treatment (annealed at 400 0 C for 1 h). It was then irradiated with γ rays from 60 Co radioactive source to study its LL characteristics and the effect of pH of the solvent on LL intensity. This has great importance for its application in dosimetry of high-energy radiation using LL. The decay curves, dose response and variation of the LL intensity with pH were studied for different doses (10 Gy-25 kGy). pH of the solutions used for studying LL was varied in the range of 0.55-13 using diluted H 2 SO 4 (acidic) and NaOH (basic) solutions. The material shows linear dose response for a broad range of doses (1.0 Gy-15 kGy). The LL intensity was found to be the maximum for a solution having pH value of 3.0. Initially the LL intensity increased with the pH of the solvent but later the intensity decreased gradually with increasing the pH till 7.0 (pH of distilled water). Another peak of the LL intensity could also be observed at around the pH of the solvent between 8.0-13.0. It was also observed that the fading of the LL intensity is more if the material is exposed to room light than its storage in dark.
The International Conference on Mathematics and Engineering Physics, 2006
For routine dosimetry, several TLD materials have been used, each having its own definite properties. In this paper, the physical TL properties of the three used commercial thermoluminescent (TL) materials, [ LiF (TLD-100), CaF 2 :Dy (TLD-200) and CaSO 4 :Dy (TLD-900) ], have been studied in order to identify the efficiency of the optimum material for gamma radiation measurements. The main investigated dosimetric properties are glow curve structure, sensitivity, dose response, fading, memory effects and sensitization. The experimental results show that the glow curve structure of the , TLD-100 includes 4 glow peaks at 135, 182, 210 & 230 o C , TLD-200 includes 2 peaks at 179 & 240 o C and TLD-900 includes 3 peaks at 123, 220 & 338 o C. The sensitivity of TLD-200 was found to be 9-20 times greater than the standard one (TLD-100), but for TLD-900, it was found 8-13 times greater than the standard one. It was found that the TL response of the three phosphors fit to a straight line in the logarithmic scale from, 50 µGy-5 Gy , 50 µGy-10 Gy and 5 µGy-10 Gy, respectively. The fading values were found to be ≈ 7.5 & 20.1 %, 14 & 32% and 10.4 & 12 % for the three phosphors, respectively, after the storage for 3 months at 25 & 50 o C, respectively. From the results which previously mentioned, calcium Sulphate doped by dysprosium has been selected for local preparation.
KCl:Dy phosphor for thermoluminescence dosimetry of ionizing radiation
Luminescence, 2013
The thermoluminescence (TL) characterizations of g-irradiated KCl:Dy phosphor for radiation dosimetry are reported. All phosphors were synthesized via a wet chemical route. Minimum fading of TL intensity is recorded in the prepared material. TL in samples containing different concentrations of Dy impurity was studied at different g-irradiation doses. Peak TL intensities varied sublinearly with g-ray dose in all samples, but were linear between 0.08 to 0.75 kGy for the KCl:Dy (0.1 mol%) sample. This material may be useful for dosimetry within this range of g-ray dose. TL peak height was found to be dependant on the concentration (0.05-0.5 mol%) of added Dy in the host.
Radiation Effects and Defects in Solids, 2012
The lyoluminescence (LL), thermoluminescence and mechanoluminescence (ML) of a γ-ray-irradiated powder of NaCl:Dy (0.05-0.5 mol%) phosphor are reported in this paper. The nature of intensity variation of the respective luminescence spectra with different γ-ray doses and with different concentrations of Dy 3+ doped in NaCl are found to be similar. The LL and ML intensities differed from each other, but their nature is found to be similar in a sublinear form up to a high dose (5.0 kGy) of γ-rays. Thus, the prepared phosphor may be useful for accidental radiation dosimetry up to a high dose (5.0 kGy) of γ-rays using the LL and ML techniques.
Instrumentation techniques for radiation dosimetry by using luminescence spectroscopy techniques
Rare-Earth-Activated Phosphors, 2022
Most biomedical applications rely on radiation therapies. Presently, radiation is used for carrying out radiotherapeutic or imaging procedures like CT scans in the field of medicine [1]. Radiation has an intensity to penetrate through human skin, and as a result of radiation tissue interaction, skin tissues could be damaged [2]. It is essential to control and tune according to the requirement of intentional and unintentional radiation exposures. Radiation can be classified into two categories, that is, charged particle radiation that consists of fast electrons and heavy charged particles, and uncharged radiation that comprises electromagnetic radiation and neutrons [3]. In radiation spectroscopy, both these radiation types interact with matter in different ways, hence, the need for radiation measurement and monitoring to control its effects in the matter accordingly.
Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl:Eu2+
Medical Physics, 2009
This work, for the first time, reports the use of europium doped potassium chloride ͑KCl: Eu 2+ ͒ storage phosphor for quantitative megavoltage radiation therapy dosimetry. In principle, KCl: Eu 2+ functions using the same photostimulatated luminescence ͑PSL͒ mechanism as commercially available BaFBr 0.85 I 0.15 :Eu 2+ material that is used for computed radiography ͑CR͒ but features a significantly smaller effective atomic number-18 versus 49-making it a potentially useful material for nearly tissue-equivalent radiation dosimetry. Cylindrical KCl: Eu 2+ dosimeters, 7 mm in diameter and 1 mm thick, were fabricated in-house. Dosimetric properties, including radiation hardness, response linearity, signal fading, dose rate sensitivity, and energy dependence, were studied with a laboratory optical reader after irradiation by a linear accelerator. The overall experimental uncertainty was estimated to be within Ϯ2.5%. The findings were ͑1͒ KCl: Eu 2+ showed satisfactory radiation hardness. There was no significant change in the stimulation spectra after irradiation up to 200 Gy when compared to a fresh dosimeter, indicating that this material could be reused at least 100 times if 2 Gy per use was assumed, e.g., for patient-specific IMRT QA. ͑2͒ KCl: Eu 2+ exhibited supralinear response to dose after irradiation from 0 to 800 cGy. ͑3͒ After x ray irradiation, the PSL signal faded with time and eventually reached a fading rate of about 0.1% / h after 12 h. ͑4͒ The sensitivity of the dosimeter was independent of the dose rate ranging from 15 to 1000 cGy/ min. ͑5͒ The sensitivity showed no beam energy dependence for either open x ray or megavoltage electron fields. ͑6͒ Over-response to low-energy scattered photons was comparable to radiographic film, e.g., Kodak EDR2 film. By sandwiching dosimeters between low-energy photon filters ͑0.3 mm thick lead foils͒ during irradiation, the over-response was reduced. The authors have demonstrated that KCl: Eu 2+ dosimeters have many desirable dosimetric characteristics that make the material conducive to radiation therapy dosimetry. In the future, a large-area KCl: Eu 2+-based CR plate with a thickness of the order of a few microns, created using modern thin film techniques, could provide a reusable, quantitative, high-resolution two-dimensional dosimeter with minimal energy dependence.
Journal of Luminescence, 2014
Nanocrytstalline K 2 Ca 2 (SO 4 ) 3 :Cu phosphor was synthesized by the chemical co-precipitation method and annealed at different temperatures (400-900 1C) for 2 h. The XRD spectrum shows the cubic structure with crystallite size $ 20 nm. The same was also confirmed from the TEM image which shows the formation of nanorods having diameter $ 20 nm and length of $ 200 nm. They are found to be quite uniform in shapes and sizes. These samples were irradiated with gamma radiation for the doses varying from 0.01 Gy to 10 kGy and their thermoluminescence (TL) characteristics and continuous wave optically stimulated luminescence (CW-OSL) have been studied. The sample annealed at 700 1C was found to be most sensitive than others. The glow curves of the nanophosphor show a major peak at around 175 1C and other two peaks of low intensity at around 85 1C and 305 1C. The traps responsible for the three thermoluminescence peaks in K 2 Ca 2 (SO 4 ) 3 :Cu are also found to be sensitive to the OSL. The qualitative correlation between TL peaks and CW-OSL response is established. The TL response of the sample annealed at 700 1C for 2 h and irradiated with different gamma doses shows a linear behavior from 0.01 up to 300 Gy and become sublinear in the range of 300 Gy-1 kGy before it saturates with further increase in the dose, while, the OSL response of the same sample shows linearity up to 1 kGy. Simple glow curve structure, easy method of synthesis, and linear dose response make the nanocrystalline phosphor a good candidate for radiation dosimetry, especially for the estimation of high doses of gamma rays where the microcrystalline phosphors generally saturate.
Proceedings of the Second International Symposium on Radiation Detectors and Their Uses (ISRD2018), 2019
It is expected that optically stimulated luminescence (OSL) dosimeters composed of Al 2 O 3 :C will be used for radiation monitoring of the high dose region in high energy accelerator facilities. The nanoDot, a small type OSL dosimeter, can easily measure absorbed doses and read with a microStar reader, a portable OSL reader. In this study, we evaluated the reliability of nanoDot OSL dosimeters for dose measurements of more than 10 Gy. In the evaluation of the upper dose limit and the uncertainty of measurement, the nanoDot OSL dosimeters were exposed to 60 Co gamma rays of 0.07-2350 Gy. They were read using a microStar with an additional neutral density filter to prevent the saturation of PMT response. Although the response of nanoDot OSL dosimeters was proportional to the absorbed dose below 1 Gy, it showed supra linearity greater than 1 Gy and it saturated approximately at 250 Gy. When the fitting line was made in the dose region of less than 1 Gy, and it was extrapolated up to 250 Gy and large deviations in the response were observed. Therefore, we proposed to use a third-ordered fitting curve, which can reduce the deviations within ± 16.8%. We concluded that the nanoDot OSL dosimeter is capable of measuring absorbed doses of up to 110 Gy by using the proposed fitting curve.