Thermoluminescence dosimeter (TLD) studies of Ca10K(PO4)7:Dy phosphor for applications in radiation dosimetry

This study reports the thermoluminescence (TL) aspects of Ca₁₀K(PO₄)₇:Dy phosphor synthesized using a wet chemical method for the first time. The X-ray diffraction (XRD) results confirm the formation of the desired crystalline phase. Surface morphological studies reveal the formation of polyhedrons and agglomerations having an average diameter of 200 nm, while energy dispersive X-ray spectroscopy (EDS) data show the presence and composition of the elements in appropriate amounts. The effect of Dy doping concentration has been studied on the TL properties with exposure to gamma radiations from the Co-60 source. The best TL response has been observed for 5 mol% Dy doping concentration. The glow curve is simple and consists of a single peak at 130°C. The effect of the heating rate has been studied on the TL glow curve, and the heating rate of 5°C/s shows the best TL response. The various TL properties such as annealing conditions, dose–response, TL linearity, fading, and reusability of the prepared phosphor have been studied to check its suitability as a good TL dosimeter (TLD). TL characterization of the phosphor reports that the TL response is linear from 5- to 2000 Gy. The results show that this phosphor can be a good TLD for the dosimetry of gamma radiations from Co-60.     

Thermoluminescence properties of the rock naturally annealed for thousands of years by flames from the earth's inner layers

The gas leak in Chimaera near Çıralı, Antalya, has been active for thousands of years. It is also known to be the source of the first Olympic flame in the Hellenistic period. The sample taken from the Chimaere seepage annealed for thousands of years was determined to be calcite-magnesian (Ca, Mg)O₃. In this study, thermoluminescence (TL) properties of calcite-magnesian annealed for thousands of years in the fire caused by methane gas were investigated for particle size, dose–response, heating rate, and fading experiments. It exhibits a clear TL glow curve with two distinct peaks positioned at 160 and 330°C, and its shape is not affected by variation in applied dose and reproduciility of experiment. There is a wide linear relationship between TL output and applied dose up to 614 Gy. Although the positions of the TL peaks are stable with the cycle of measurement, a poor reusability was observed in terms of the area under the TL glow curve and peak intensity.     

Thermoluminescence in pumice stone collected from the Mediterranean coast

Pumice is a low-density, light-coloured volcanic rock (igneous rock) formed when the magma from a volcanic eruption is suddenly cooled. It has a porous structure and can be different colours and have different densities. Pumice stone, unlike other rock, does not sink in water because it has a low density. In the present study, the thermoluminescent (TL) dosimetric characteristics, such as the dose–response, TL signal fading as a function of storage time, heating rate, and reusability of pumice collected on the Mediterranean coast were investigated. From this study, it was concluded that the pumice stone showed TL properties with a TL glow curve including an obviously wide peak at ∼200°C. A wide linear dose–response region up to 144 Gy, low fading of the TL signal when it was kept in a dark room for a long time, and poor reusability properties were observed for dosimetry use.     

Study of thermoluminescence in turtle shell fossils using radiation dosimetry

The present study describes for the first time thermoluminescence (TL) characterization of turtle shell. A fossil shell was collected from the Dongargaon area in the Chandrapur district of Maharashtra, India. TL was recorded and a comparative study of TL for the above material was performed to understand the special TL characteristics of the shell. The shell was irradiated with ⁶⁰Co γ‐radiation to study its TL properties. The sample displayed two good TL peaks at 135°C and 255°C. A linear dose–response curve for the irradiated sample was produced for the dose range 0.79–28.5 kGy; this sample of turtle shell (fossil) may be useful as a high dose dosimetry phosphor in this range. This geological sample was further characterized using X‐ray diffraction to confirm its phase structure and by scanning electron microscopy , Fourier transform infrared and wavelength dispersive X‐ray fluorescence spectroscopy to determine morphology, vibration, and elemental composition as ppm or percentage of the sample, respectively. Kinetic parameters of the TL glow peak were calculated using three different methods.     

Thermoluminescence properties of gamma‐irradiated nano‐structure hydroxyapatite

The suitability of nano‐structured hydroxyapatite (HAP) for use as a thermoluminescence dosimeter was investigated. HAP samples were synthesized using a hydrolysis method. The formation of nanoparticles was confirmed by X‐ray diffraction and average particle size was estimated to be ~30 nm. The glow curve exhibited a peak centered at around 200 °C. The additive dose method was applied and this showed that the thermoluminescence (TL) glow curves follow first‐order kinetics due to the non‐shifting nature of T_m after different doses. The numbers of overlapping peaks and related kinetic parameters were identified from T_m–T_stop through computerized glow curve deconvolution methods. The dependence of the TL responses on radiation dose was studied and a linear dose response up to 1000 Gy was observed for the samples. Copyright © 2015 John Wiley & Sons, Ltd.     

Photoluminescence and thermoluminescence dosimetry properties of Ag/Y co-doped ZnO nanophosphor for radiation measurements

This work explores the thermoluminescence (TL) and photoluminescence (PL) properties of Ag/Y co-doped zinc oxide (ZnO) nanophosphor. The proposed dosimeter was prepared by the coprecipitation method and sintered at temperatures from 400°C to 1000°C in an air atmosphere. Raman spectroscopy was studied to investigate the structural features of this composition. The new proposed dosimeter revealed two peaks at 150°C and 175°C with a small shoulder at high temperature (225°C). The PL spectrum showed strong green emissions between 500 to 550 nm. The Raman spectrum showed many bands related to the interaction between ZnO, silver (Ag), and yttrium oxide (Y₂O₃). The rising sintering temperature enhanced the TL glow curve intensity. The Ag/Y co-doped ZnO nanophosphor showed an excellent linearity index within a dose from 1 to 4 Gy. The minimum detectable dose (MDD) of the Ag/Y co-doped ZnO nanopowder (pellets) equaled 0.518 mGy. The main TL properties were achieved in this work as follows: thermal fading (37% after 45 days at 1 and 4 Gy), optical fading (53% after 1 h and 68% after 6 h by exposure to sunlight), effective atomic number (27.6), and energy response (flat behavior from 0.1 to 1.3 MeV). Finally, the proposed material shows promising results nominated to be used for radiation measurements.     

Zinc silicate phosphor: Insights of X-ray induced and temperature enabled luminescence

The present investigation deals with the effect of calcination temperature on the structural and thermoluminescent (TL) properties of Zn₂SiO₄ materials. For this study, Zn₂SiO₄ was prepared via a simple hydrothermal route and calcinated at temperatures from 700°C to 1100°C in an air atmosphere. TL data of all Zn₂SiO₄ samples showed two peaks at around 240°C and 330°C due to the formation of the luminescence centre during X-ray irradiation. More interestingly, the Zn₂SiO₄ sample calcinated at 900°C exhibited a shift in the TL peak (282°C and 354°C) with an optimal TL intensity attributed to its good crystallinity with a well-defined hexagonal plate-like morphology. X-ray-irradiated Zn₂SiO₄ samples calcinated at 900°C exhibited a high-temperature TL glow curve peak, suggesting that the present material could be used for high-temperature dosimetry applications.     

Thermoluminescence properties of unique Rosso Levanto marble

This marble extracted from deposits in Elaz?? in Turkey resembles red meat in appearance and is only found in Elaz??. This type of marble has been widely used in the most famous architectural structures and buildings. In this study, the thermoluminescence (TL) properties of a unique marble that originated from Turkey, named Rosso Levanto, were investigated. Two distinct TL peaks were observed at 160°C and around 375°C. Particle size experiments showed that best TL intensity was seen at 200 μm particle size and therefore dose–response, heating rate, cycle of measurement and fading experiments were carried out on powdered samples with a particle size of 200 μm. The findings revealed good linearity in dose–response, observed up to 0.5 kGy. The reproducibility experiment gave good results, but peak intensity decreased by about 40% in first 6 h of storage in a dark room.     

Thermoluminescence characterization of Ag‐doped Li2B4O7 single crystal materials

In this study, the thermoluminescence (TL) characteristics of Ag‐doped and undoped lithium tetraborate (Li₂B₄O₇, LTB) materials, grown using the Czochralski method, were reported. The TL properties of LTB:Ag, such as glow curve structure, dose response, fading and reproducibility, were investigated. The glow curve of the Li₂B₄O₇:Ag single crystal consists of four peaks located at approximately 75, 130, 190 and 275°C; in undoped LTB, the single crystal shows a broad glow curve with peaks at 65, 90, 125, 160 and 190°C using a heating rate of 5°C/s in the 50–350°C temperature region. The high temperature peak of Ag‐doped sample at 275°C has a nonlinear dose response within the range from 33 mGy to 9 Gy. There is a linear response in the range of 33–800 mGy; after which, a sublinear region appears up to 9 Gy for Ag‐doped LTB single crystal. For undoped single crystal, the dose response is supralinear for low doses and linear for the region between 1 and 9 Gy. The thermal fading ratio of the undoped material is almost 60% for the high temperature peak after 7 days. Ag‐doped LTB single crystal exhibits different behaviour over a period of 7 days.     

Dosimetric properties of lithium borate glass doped with dysprosium

Characterization of thermoluminescence (TL) properties of lithium borate glass samples doped with different concentrations of dysprosium (Dy) was carried out. Samples were prepared using a melting method at 1100°C and irradiated with β‐particles. The glass samples doped with 0.1% Dy displayed the best TL dosimetric properties compared with other compositions. Deconvoluted analyses of the glow curves displayed five overlapping TL glow peaks located between 392.0 and 510.3 K. A good linear TL dose–response for β‐particles was obtained in the dose range 66.6 mGy to 33.3 Gy. The minimum detectible dose was evaluated to be 205.4 μGy and samples revealed thermal fading in 312 h to 29% of their original value.     

OSL and thermally assisted OSL response in dental enamel for its possible application in retrospective dosimetry

Dental enamel was studied for its thermoluminescence (TL) and optically stimulated luminescence (OSL) defects. The TL studies showed a wide glow curve with multiple peaks. The thermally assisted OSL (TA-OSL) studies showed that the integrated TA-OSL and thus OSL signal increases with readout temperature between 100 and 250 °C, due to the temperature dependence of OSL. The thermally assisted energy E _A associated with this increase is found to be 0.21 ± 0.015 eV. On the other hand, the signal intensity decreases with temperature between 260 and 450 °C. This decrease could be due to depletion of OSL active traps or possible thermal quenching. The increase of the OSL signal at increased temperature can be used to enhance the sensitivity of dental enamel for ex vivo measurements in retrospective dosimetry. The emission and excitation spectra of its luminescence centers were studied by photoluminescence and were found to be at 412 and 324 nm, respectively. It was found to possess multiple OSL active traps having closely lying photoionization cross sections characterized by continuous wave OSL and nonlinear OSL methods. The investigated dental enamel samples showed a linear OSL dose response up to 500 Gy. The dose threshold was found to be 100 mGy using a highly sensitive compact OSL reader with blue LED (470 nm) stimulation.     

Thermoluminescence characteristics of calcite with a Gaussian process regression model of machine learning

Thermoluminescence (TL) is defined as a luminescence phenomenon that can be detected when an insulator or semiconductor is thermally stimulated. Defective crystals store radiation until they are stimulated. Thermoluminescence is a method of monitoring the absorbed dose of dosimeters. The irradiation crystal is heated to 500°C to display the absorbed dose as a luminescent light. The TL dosimetric properties of calcite obtained from nature were investigated in this study. Machine learning was also examined using Gaussian process regression (GPR) for stimulated TL characteristics. According to the experimental output, the TL glow curve had two main peaks located at 90°C and 240°C with good dosimetric properties. In the four regression models of GPR, the data for the heating rate of 3°C s⁻¹ have the lowest residual.     

A new less toxic polymer gel dosimeter: Radiological characteristics and dosimetry properties

PurposeA new polymer gel dosimeter recipe was investigated that may be more suitable for widespread applications than polyacrylamide gel dosimeters, since the extremely toxic acrylamide has been replaced with the less harmful monomer 2-Acrylamido 2-Methyl Propane Sulfonic acid (AMPS).MethodsThe new formulation was named PAMPSGAT. The MRI response (R2) of the dosimeters was analyzed for conditions of varying dose, dose rate, and temperature during scanning. Radiological properties of the PAMPSGAT polymer gel dosimeter were investigated.ResultsThe dose-response (R2) of AMPS/Bis appears to be linear over a dose range 10–40 Gy. The percentage of difference between the R2 values for imaging at 15 °C and MRI room temperature is about 4.6% for vial with 40 Gy absorbed dose which decreased to less than 1% for imaging at 20 °C. The percentage difference of Zeff of PAMPSGAT gel and soft tissue was less than 1% in the practical energy range (100 KeV–100 MeV). The electron density of the PAMPSGAT polymer gel was 2.9% higher than that of muscle. Results showed that the sensitivity of PAMPSGAT polymer gel dosimeter irradiated by ⁶⁰Co (energy = 1.25 MeV) is about 27.7% higher than that of irradiated using a 6 MeV Linac system.ConclusionsTemperature during MRI scanning has a small effect on the R2 response of the PAMPSGAT polymer gel dosimeter. Results confirmed tissue equivalency of the PAMPSGAT polymer gel dosimeter in most practical energy range. The PAMPSGAT polymer gel dosimeter response depends on energy and dose rate.     

Comparison of thermoluminescence characteristics in γ‐ray and C5+ ion beam‐irradiated LiCaAlF6:Ce phosphor

We compare the thermoluminescence (TL) behavior of Ce³⁺ ion‐activated LiCaAlF₆ exposed to γ‐rays and a carbon ion beam. The reported phosphor is synthesized using an in‐house precipitation method with varying concentrations of activator ion and is characterized by X‐ray diffraction (XRD) and TL. Rietveld refinement is performed to study the structural statistics. The TL glow curve consists of a prominent glow peak at 232°C with three shoulders at 115, 159 and 333°C when exposed to γ‐rays from a ⁶⁰Co source. When exposed to a C⁵⁺ ion beam, the TL glow curve consists of five peaks with peak temperatures near 156, 221, 250, 287 and 330°C, and is found to vary slightly with changing fluence. Glow curve convolution deconvolution (GCCD) functions are applied to the TL curves for complete analysis of the glow curve structure and TL traps. The order of kinetics (b), activation energy (E) and frequency factor are determined using Chen's peak shape method and theoretical curves are drawn using GCCD functions. A track interaction model (TIM) is used to explain the sublinearity/saturation at higher fluences. Ion beam parameters are analyzed using Monte‐Carlo simulation‐based SRIM‐2013 code. Copyright © 2016 John Wiley & Sons, Ltd.     

Luminescence characterization of Dy and Eu doped Na6Mg(SO4)4 phosphors

A series of single‐phase phosphors based on Na₆Mg(SO₄)₄ (Z_eff = 11.70) doped with Dy and Eu was prepared by the wet chemical method. The photoluminescence (PL) and thermoluminescence (TL) properties of Dy³⁺‐ and Eu³⁺‐activated Na₆Mg(SO₄)₄ phosphors were investigated. The characteristic emissions of Dy³⁺ and Eu³⁺ were observed in the Na₆Mg(SO₄)₄ host. The TL glow curve of the Na₆Mg(SO₄)₄:Dy phosphor consisted of a prominent peak at 234°C and a very small hump at 158°C. The TL sensitivity of the Na₆Mg(SO₄)₄:Dy phosphor was found to be four times less than the commercialized CaSO₄:Dy phosphor. The TL dose–response of the Na₆Mg(SO₄)₄:Dy phosphor was studied from a dose range of 5–10 kGy and the linear dose–response was observed up to 1 kGy which is good for a microcrystalline phosphor. Trapping parameters for both the samples were calculated using the Initial Rise and Chen's peak shape methods.     

Investigation of thermoluminescence glow curves in quartz extracted from the Central Eastern Desert,Egypt

The current study investigated the thermoluminescence (TL) properties of milky quartz samples collected from the Central Eastern Desert, Egypt. The crystallinity and the elemental concentrations of the milky quartz samples were examined using X‐ray diffraction and an atomic absorption spectrometer. Samples were irradiated using a gamma source at different doses from 250 mGy up to 2 kGy. For annealing, the samples were heated at 400°C for 1 h, followed by slow cooling. Kinetic analyses for the TL glow curves were performed using new designed TL deconvolution software. The glow curves were composed of six overlapped trapping sites at 428, 468, 498, 545, 586, and 639 K. The samples also displayed a linear dose–response from 0.25 Gy up to 20 Gy and a supralinear response from 20 Gy up to 200 Gy. The samples exhibited very low sensitivity for gamma radiation compared with LiF and the minimum detectable dose was 545 μGy. From its linear nature, it was observed that the sensitivity had changed. This study recommends starting measurements of these milky quartz samples after 4 days to give established measurements.     

Effect of annealing temperature and dopant concentration on the thermoluminescence sensitivity in LiF:Mg,Cu,Ag material

LiF:Mg,Cu,Ag is a new dosimetry material that is similar to LiF:Mg,Cu,P in terms of dosimetric properties. The effect of the annealing temperature in the range of 200 to 350°C on the thermoluminescence (TL) sensitivity and the glow curve structure of this material at different concentrations of silver (Ag) was investigated. It has been demonstrated that the optimum values of the annealing temperature and the Ag concentration are 240°C and 0.1 mol% for better sensitivity, respectively. The TL intensity decreases at annealing temperatures lower than 240°C or higher than 240°C, reaching a minimum at 300°C and then again increases for various Ag concentrations. It was observed that the glow curve structure altered and the area under the low temperature peak as well as the area under the main dosimetric peak decreased with increasing annealing temperature. The position of the main dosimetric peak moved in the direction of higher temperatures, but at 320 and 350°C annealing temperatures, it shifted to lower temperatures. It was also observed that the TL sensitivity could partially be recovered by a combined annealing procedure.     

Synthesis and thermoluminescence characterizations of Sr2B5O9Cl:Dy3+ phosphor for TL dosimetry

The photoluminescence (PL) and thermoluminescence (TL) displayed by Dy‐activated strontium haloborate (Sr₂B₅O₉Cl) were studied. A modified solid‐state reaction was employed for the preparation of the phosphor. Photoluminescence spectra showed blue (484 nm) and yellow (575 nm) emissions due to incorporation of Dy³⁺ into host matrix. The Dy‐doped (0.5 mol%) Sr₂B₅O₉Cl was studied after exposure to γ‐irradiation and revealed a prominent glow curve at 261°C with a small hump around 143°C indicating that two types of traps were generated. The glow peak at the higher temperature side (261°C) was more stable than the lower temperature glow peak. The TL intensity was 1.17 times less than that of the standard CaSO₄:Dy thermoluminescence dosimetry (TLD) phosphor, the phosphor showed a linear dose–response curve for different γ‐ray irradiation doses (0.002–1.25 Gy) and fading of 5–7% was observed for higher temperature peaks upon storage. Trapping parameters and their estimated error values have been calculated by Chen's peak shape method and by the initial rise method. Values of activation energies estimated by both these techniques were comparable. The slight difference in activation energy values calculated by Chen's peak shape method indicated the formation of two kinds of traps Furthermore, slight differences in frequency values are due to various escaping and retrapping probabilities. Copyright © 2014 John Wiley & Sons, Ltd.     

Characteristics of a novel polymer gel dosimeter formula for MRI scanning: Dosimetry,toxicity and temporal stability of response

The present study intended to investigate the composition of a new polymer gel dosimeter. The new composition would be more suitable for a wide range of applications in comparison to polyacrylamide gel dosimeter since its extremely toxic acrylamide has been replaced with less harmful monomer i.e. 2-Acrylamido-2-MethylPropane Sulfonic acid (AMPS). To this end, the PAGAT gel dosimeter formula was used as a basis to test the new formulation of polymer gel dosimeter with a different monomer (AMPS) instead of acrylamide by using the %6 T and %50 C to the formula. The new formulation was named PAMPSGAT (Poly AMPS, Gelatin and THPC) polymer gel dosimeter. Moreover, the MRI response (R₂) of dosimeters was analyzed in terms of different dose range as well as post-irradiation time. The results indicated that the dose-response (R₂) of AMPS/Bis had a linear trend over a wide dose range. Furthermore, the results showed an acceptable temporal stability for the new polymer gel dosimeter.     

Photo and thermoluminescence of KMgSO4F: Ce and :Mn phosphors

KMgSO₄F:Ce and KMgSO₄F:Mn phosphors were prepared by a wet chemical method and studied for their photoluminescence (PL) and thermoluminescence (TL) characteristics. PL emission of KMgSO₄F:Ce peaked at around 440 nm for the excitation at 377 nm due to 5d → 4f transition, while KMgSO₄F:Mn had a peak at 540 nm for an excitation at 363 nm and 247 nm due to ⁴T_1g → ⁶A_1g transition. The phosphors also showed good thermoluminescence characteristics when they were exposed to γ‐rays at a 5 Gy dose at the rate of 0.36 kGyh^?1. KMgSO₄F:Ce exhibited a single thermoluminescence (TL) peak at around 167 °C and KMgSO₄F:Mn also exhibited a single TL peak at around 177 °C. Possible trapping parameters such as order of kinetics (b), the geometrical factor (μ_g), the frequency factor (s) and the activation energy were also evaluated by Chen's half width method. This article discusses fundamental PL and TL characteristics in inorganic fluoride material activated by Ce³⁺ and Mn²⁺ ions and prepared by a wet chemical method. Copyright © 2014 John Wiley & Sons, Ltd.