Thermoluminescence Dose Response Research Articles

Thermoluminescence characteristics of gamma-irradiated Gd:Mg doped silica glass

This study explores the characteristics of thermoluminescence (TL) yield of silica glass doped with Gd2O3 and MgO for dosimetry via sol-gel route, with varying concentrations of rare earth metal oxides, ranging from 0.1 to 0.8 mol%. Gamma irradiation was delivered using 1.25 MeV 60Co, with entrance doses of 2–10 Gy. The characterization of Gd:Mg-doped SiO2 included assessing TL dose response, sensitivity, linearity index, glow curve, and fading. It has been found that 0.2 mol% Gd:Mg-doped SiO2 shows promising TL dosimetric properties due to its high linearity, high sensitivity, and low thermal fading. In addition, it demonstrated exceptional dosimetric response across the entire dose range studied, with a coefficient of determination R2 exceeding 91%. A computerized glow curve deconvolution method was conducted to determine the kinetic parameters by using Glowfit software. The glow curves include five peaks associated with activation energies and frequency factors with values 0.88–2.42 eV and 5.58 × 106–7.22 × 1026 s−1, respectively. The 0.2 mol% Gd:Mg-doped SiO2 demonstrates minimal fading effects, retaining a significant portion of the TL signal with ∼33% of the initial signal lost over 28 days post-irradiation. The results indicate that the Gd:Mg-doped SiO2 offers a promising performance as a low-cost passive radiation dosimeters.

Tempered glass as a thermoluminescent medium for retrospective dosimetry

Globally, the use of nuclear facilities and the potential risks associated with the dispersal of ionizing radiation due to natural disasters or technical failures are on the rise. These risks can have severe consequences for the environment and all living organisms, particularly humans. There is currently no practical method available to accurately estimate the radiation doses received by the surrounding areas and individuals in such situations. To address this issue, retrospective dosimetry can be employed to estimate the actual radiation dose, followed by the implementation of remediation techniques. Considering this need, tempered glass, which is commonly used as a screen protector for smartphones by the general public, has been identified as a promising medium for retrospective dosimetry. The present study aimed to investigate the thermoluminescence (TL) properties of six different types of tempered glass subjected to 60Co gamma rays, specifically examining the TL dose response, linearity, repeatability, and fading. Among the various glass samples tested, HD anti-peep tempered glass demonstrates a highly linear dose-response and the greatest dose sensitivity within the examined dose range of 2–50 Gy. Additionally, the HD anti-peep tempered glass exhibits minimal loss of TL yield (∼23%) at 28 days post-irradiation, making it particularly suitable for use as a retrospective dosimeter.

Synthesis, photo- and thermo-luminescent properties of Mg2P2O7:Tm3+ phosphors

In this work, both undoped and Thulium (Tm3+) doped (0.3–10 mol%) magnesium pyrophosphate (Mg2P2O7) powders were synthesized by the solvent evaporation method to study their photo-and thermoluminescent properties. Two crystalline phases were observed in the powders by X-Ray diffraction (XRD), the main phase being Mg2P2O7 and the second one thulium phosphate (TmPO4). The superficial morphology was analyzed by scanning electron microscopy (SEM), which revealed that the powders are agglomerates with an undefined form and grains with non-uniform size distribution. The photoluminescence (PL) emission spectra of Tm3+ doped powders show the 1D2 → 3F4 transition, associated with Tm3+ ions, at 452 and 458 nm. The thermoluminescence (TL) properties were analyzed in the undoped and Tm3+ doped powders exposed to 90Sr beta source. The TL glow curve of Tm3+ doped powders exhibits three maxima at about ⁓64–66 °C, ⁓198–202 °C, and ⁓301 °C. The TL dose-response is sub-linear from 0.11 to 0.54 Gy, linear between 0.79 and 24.95 Gy, and supra-linear from 34.99 to 599.95 Gy. Acceptable repeatability with a coefficient of variation of ∼1% was obtained after ten cycles of irradiation and readout. At 63 d of storage, the powders show fading of 30%, and at 1.6 years (585 d), the integrated TL intensity decays by 47%. The kinetic parameters of activation energy and frequency factor were evaluated using the Initial Rise, Booth, Bohum, and Porfianovitch (BBP) and Hoogenstraaten methods and Glow Curve Deconvolution with a general order kinetic model.

Determination of the kinetic parameters of BeO luminescent material using different methods towards X-ray irradiation

In this work, the thermoluminescence (TL) and optically stimulated luminescence (OSL) kinetics of a recently developed beryllium-oxide dosimeter (BeOR) were studied with different methods. The TL and OSL dose responses were also established for an X-ray dose interval of 2–10 Gy. The TL kinetic parameters were determined using three methods, namely: the peak shape (PS), the first-order kinetics (FOK) using Glow-Fit, and the general-order kinetics (GOK) using computerized glow-curve deconvolution (CGCD). TL glow curves of the irradiated BeOR show two distinct TL experimental peaks at ∼250 and ∼379 °C under a heating rate of 5 °C/s. The PS method demonstrates a kinetics order of about two (∼2) for the first peak, whereas the second peak follows first-order kinetics. The activation energies resulting from PS method range from 0.98±0.03 to 1.01±0.05 eV for the first peak and from 1.56±0.07 to 1.58±0.08 for the second peak. The FOK-Glow-Fit show three deconvolution peaks (1.02, 1.05, and 1.07 eV) for the first TL experimental peak and one peak (1.94 eV) for the second experimental peak. The GOK-CGCD method reveals three peaks of ∼1.04, 1.6 (experimental peak1), and ∼2.1 eV (experimental peak2). The TL kinetic parameters were established and compared for the three considered methods. Based on the TL kinetics study, OSL kinetics parameters of BeOR were also determined. The established TL and OSL dose responses of studied dosimeter show linear behaviour that allow effective dosimetry application in photon radiotherapy.

Kinetic modeling of charge transfer following photon bleaching post-irradiation of spatially correlated trapping and luminescent centers in LiF:Mg,Ti

Illumination of LiF:Mg,Ti by photons of energy 3.65 eV and levels of fluence from 1.2 1018 ph cm−2 to 3.6 1018 ph cm−2 results in a decrease of the thermoluminescence (TL) dose response supralinearity of peak 5 in the glow curve of LiF:Mg,Ti. No further effect on the dose response is observed at higher photon fluences up to 1.4 × 1019 ph cm−2. The threshold of dose response non-linearity usually reported at a dose of 1 Gy, is increased to 30 Gy. A kinetic model is described herein in the framework of conduction band/valence band solid state theory incorporating spatially correlated trapping centers (TCs) and luminescent centers (LCs). The model successfully simulates the bleaching action of the 3.65 eV photons on the increased region of TL dose response linearity as resulting from the depletion of the occupied trapping centers and to a lesser degree by charge transfer via the conduction band between the various configurations of the TC/LC system associated with composite peak 5.

Simulation of thermoluminescence signals at very low dose rates and low doses: Implications for dosimetric applications

During luminescence dosimetry applications, samples are irradiated in the laboratory with irradiation dose rates of the order of 0.1 Gy/s. By contrast, samples in nature are irradiated with a dose rate many orders magnitude smaller, typically 1 mGy/year. In this paper, the effect of very low dose rates and also low doses on thermoluminescence (TL) signals is investigated using the basic one-trap one-recombination center model (OTOR). The simulations showed that at very low dose rates the assumptions of quasi-equilibrium conditions (QE) are violated. This violation of QE conditions results in a significant distortion of the shapes of TL glow curves, with the result that the peak shape methods of analysis fail to produce the correct activation energy E of the traps. At the same time, the estimated half-life of the electrons traps is found to increase significantly at very low doses. The dose response of the sample at very low dose rates is simulated for both the irradiation stage and the subsequent heating stage. The dose response of the integrated TL signal is found to coincide with the dose response during the irradiation stage. However, the TL dose response measured in terms of the peak height shows a significant under-response at very low doses, making the whole dose response curve superlinear before the onset of saturation. The peak height under-response is due to the clear violation of QE conditions at very low doses and dose rates. The reported distortion of the TL glow curves and the existence of superlinearity of the TL signals at low dose rates, have important implications for the analysis of TL signals. Researchers need to be aware of the possibility that both of these effects may be present, since they can influence the analysis of experimental data and can lead to the wrong conclusions in dosimetric applications.

Thermoluminescence of Natural Quartz Grains Beside Huguangyan Maar Lake

In order to study the relationship between the thermoluminescence (TL) properties of natural quartz crystals and the irradiation history, the TL test of quartz particles was carried out on volcanic ash near Huguangyan Maar Lake in Zhanjiang City. The TL glow curve and dose response of quartz were measured. The parameters of TL traps are calculated, and the activation energies corresponding to the TL peaks of 260, 310 and 365 °C of quartz grains are 1.34, 1.44 and 1.51eV, respectively. The peak position of the TL glow curve changes mildly with the increase of irradiation dose of quartz particles, indicating that the energy of a TL trap is not a single value, but an energy distribution; in the range of 355 °C to 375°C, the TL sensitivity changes greatly with the increase of the historical irradiation dose.

THE THERMOLUMINESCENCE (TL) DOSE RESPONSE OF COMPOSITE PEAK 5 IN LIF:MG,TI (TLD-100): DEPENDENCE ON THE ORDER OF KINETICS.

A seeming contradiction in the prediction of the spatially correlated trapping center/luminescent center model applied to LiF:Mg,Ti has been the linear/supralinear behavior of the dose response of glow peak 5a. In the TC/LC model, the localised electron-hole recombination, giving rise to glow peak 5a, is expected to result in an extended region of linear dose response. Deconvolution of the glow curves based on first order kinetic peak shapes results, however, in a dose response of peak 5a, which closely resembles the linear/supralinear dose response of peak 5. It is demonstrated herein that when general-order kinetics peak shapes are used for peak 5a, the analysis can result in a linear dose response of glow peak 5a up to dose levels as high as 30Gy, well beyond the 1-Gy onset of supralinearity of peak 5. The extended linearity suggests a resolution of the contradiction.

Study of thermoluminescence, photoluminescence and dosimetry for the YAGG:Ce (Y2.96Al3.4Ga1.6O12:0.04Ce) phosphor

The comprehensive effect of ionizing radiation should be considered in the use and or analysis of certain electronic equipment. Fluorescent powders are widely used in electronic equipment, so they are attempted to be used as thermoluminescence (TL) dosimeter directly. Green YAGG:Ce phosphors were prepared by a high-temperature solid-state reaction method. The TL glow curves, TL dose response, TL three-dimensional (3D) spectra (80 K–800 K) and photoluminescence spectra for the phosphors were measured. The measurement results show that the luminescence peak temperature for the sample occurs at approximately 458 K and the luminescence peak temperatures in the TL 3D spectra are located at 130 K, 240 K and 458 K; there are four kinds of activation energies of traps in the material; the TL response of each component for the YAGG:Ce phosphor shows good linearity and the detection sensitivity of the phosphor is estimated to be less than 2 mGy. TL 3D spectra and PL spectra show that the luminescence from the phosphors arises from the 2D3/2 → 2F5/2,7/2 transition of Ce ions, and the TL 3D spectra at 130 K, 240 K and 458 K are almost the same, which proves that the temperature can hardly change the relative probability of the 2D3/2 → 2F5/2,7/2 transitions. The results show that YAGG:Ce could be used as dosimeter material.

Thermoluminescence properties of Er-doped borophosphate glass for beta radiation

The thermoluminescence (TL) dosimetric properties of metaphosphate glass system were investigated. The glass system of (Er2O3)1-(SrO)24-(B2O3)25-(P2O5)50 was prepared using a melt quenching technique. The glass system was characterized using different techniques. The internal structure of the system was probed with XRD and FTIR technique was used to identify the types of bonds between the involved atoms. The analysis of TL glow curve was studied by different methods and was found to be composed of six trap peaks at energies 0.817, 0.846, 0.958, 1.190, 1.248, and 1.347 eV. The TL dose–response signal was found to be linear in the range of 0.22–55 Gy. The activation energies were determined by three methods: glow curve deconvolution (CGCD), Tmax-Tstop method and Peak shape (PS) methods. The results of the three methods exhibited a good agreement with each other. Highlights The thermoluminescence properties of metaphosphate glass were investigated. The glass samples were irradiated to different doses of beta particles. The deconvolution indicated the presence of six overlapping glow peaks. The activation energies were determined by three methods and the results of all the methods exhibited a good agreement.

Thermoluminescence properties and identification of irradiated cocoa beans during long-term storage

This work reports on the thermoluminescence (TL) properties and detection of contaminating minerals isolated from Mexican cocoa beans irradiated with gamma radiation and stored for 4 years. Contaminating minerals isolated from cocoa beans consisting of quartz, diopside, plagioclase, albite, and iron oxide with irregular and rectangular grains and average length of 135 μm. Cocoa beans are detected as irradiated even after 4 years of storage using the shape and maximum temperature of the TL glow curve of contaminating minerals. The TL properties of dose-response, and fading of minerals were also analysed. The TL dose-response is linear from 5 to 100 Gy, supra-linear between 250 and 1000 Gy, and sub-linear above 1500 Gy. Based on the TL1/TL2 ratio the minerals are identified as irradiated from 250 Gy to 4500 Gy in the dose-response test and after different storage times in the darkness at room temperature. A continuum trap distribution can be associated with the TL glow curve of minerals using the Tm-Tstop method. First order kinetic peaks were used in the Glow Curve Deconvolution of natural and irradiated (1 and 10 kGy) TL curves.

Thermoluminescence kinetic parameters of proton-irradiated germanium doped flat-shape optical fibres

Glow curve is a key element in thermoluminescence (TL) studies as it provides on-the-ground understanding on the trapping mechanism inside the crystal lattice and hence stability of the TL material. In the present work, luminescence mechanism of the in-house fabricated germanium doped (Ge-doped) flat-shape silica optical fibres have been investigated following irradiation by 150-MeV proton beams. Results of TL dose-response showed that there is a linear relationship between TL response and proton doses from 1 to 10 Gy, with a coefficient of determination close to one. The structure of glow curve remains unchanged throughout the studied dose range with a maximum glow peak dominated at temperature of within 250–290 °C. A Tmax-Tstop plot reveals not only horizontal regions but also smooth slopes, indicative of the presence of a continuum distribution of glow peaks and trap depth. A computerised glow curve deconvolution analysis of the respective fibre glow-curves demonstrated that they were composed of five strongly overlapping peaks underlying a broad TL spectrum, obtaining figures of merit in the range of 0.56–1.64%. The main physical kinetic parameters (activation energy and frequency factor) of the fitted glow peaks were obtained using GlowFit software. The data suggest that the TL glow peaks of the Ge-doped silica optical fibres obey second-order kinetics.

Dosimetric characteristics of Gd-doped silica glass subjected to neutron and gamma irradiations

The dosimetric characteristics of newly developed gadolinium (Gd) glass dosimeter produced via sol-gel method are reported. Irradiation were made using a 750 kW neutron flux thermal power and 1.25 MeV 60Co gamma rays with entrance doses from 2 to 10 Gy. Investigation has been done on various Gd dopant concentrations, ranging from 1 to 10 mol%. The Gd-doped silica glass have been characterised for thermoluminescence (TL) dose response, sensitivity, linearity index, glow curve and kinetic parameter analysis. For particular dopant concentration obtained in 6 mol% Gd, the least squares fit shows the change in TL yield, correlation coefficient (r2) of better than 0.980 (at 95% confidence level), with neutron and gamma exposure to be 8 and 4 times greater than that of 1 mol% Gd, respectively. Broad peaks in the absence of any sharp peak observed in the glow curve confirms the amorphous nature of the prepared glass. A glow curve of Gd-doped SiO2 sample is observed with a single prominent peak (Tm) within 200–250 °C (peak shifting appears with respect to the increment of dopant concentration) and 350 °C (for all respective Gd dopants) for neutron and gamma irradiations, respectively. Deconvolution shows the glow curves of the Gd-doped SiO2 glass to be formed of seven and five overlapping peaks, with figures of merit below 2% (FOM) of between 1.38-1.79 and 1.30–1.97 for the particular neutron and gamma irradiations, respectively. Through use of Glowfit deconvolution software, the key trapping parameters of activation energy, E and frequency factor, s−1 were calculated for the Gd-doped SiO2 glass. The mechanism of TL yield with the gradual increase in Gd concentrations and doses is explained upon the incorporation of Gd and radiation damage that change the structure of the electron traps in the glass matrix. These early results indicate that selectively screened Gd-SiO2 glass can be developed into a promising TL system towards dosimetric applications.

Investigation of Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) Properties of Dy3+ Doped CaB4O7 Nanoparticles.

CaB4O7 nanoparticles doped with different concentrations of Dy3+ were prepared by using solution combustion method. The recorded Thermoluminescence (TL) and Optically stimulated luminescence (OSL) of CaB4O7:Dy samples for different concentrations of Dy3+ irradiated with 6Gy of X-Ray shows concentration quenching effect above 0.05 at.wt% of Dy3+ concentrations. The TL and OSL kinetic parameters of glow curves were evaluated using "tgcd" and conventional fitting methods. The TL glow curve of the CTB:(0.05%)Dy have five individual glow peaks with maximum peak temperatures at 410, 470, 525, 563 and 593K. TL Dose response of the X-Ray irradiated CTB:(0.05%)Dy is also found to be linear in the range of 1Gy to 50Gy. The OSL glow curves of the CTB:Dy nanoparticles follow non-first order kinetics and can be fitted with the sum of three first order decay curves. Fading characteristics of the TL and OSL signals are studied for 40days and found to be very stable.

Thermoluminescence characterization and kinetic parameters of Dy3+ activated Ca3Y2B4O12

In this study, thermoluminescence (TL) characteristics of Ca3Y2B4O12:xDy (0 ≤ x ≤ 0.07) phosphor samples were studied. The samples were exposed to beta irradiation in the dose range from 0.1 Gy to 100 Gy to investigate TL dose response. The concentration of Dy3+ in Ca3Y2B4O12 phosphor was optimized and found to be 1 mass % in terms of TL signal quality. The TL glow curve appears to be consisted of three peaks which were discernible at 72 °C, 280 °C and 376 °C. The trapping parameters (E, b, and s) were calculated using initial rise (IR), and variable heating rate (VHR) techniques. The trapping parameters, order of kinetics, frequency factor, and figure of merit have been all determined by means of the Glow Curve Deconvolution (GCD) method (tgcd:An R package). Ca3Y2B4O12:Dy phosphor displays efficient thermoluminescence properties.

Developing an internally consistent methodology for K-feldspar MAAD TL thermochronology

Luminescence thermochronology and thermometry can quantify recent changes in rock exhumation rates and rock surface temperatures, but these methods require accurate determination of several kinetic parameters. For K-feldspar thermoluminescence (TL) glow curves, which comprise overlapping signals of different thermal stability, it is challenging to develop measurements that capture these parameter values. Here, we present multiple-aliquot additive-dose (MAAD) TL dose–response and fading measurements from bedrock-extracted K-feldspars. These measurements are compared with Monte Carlo simulations to identify best-fit values for recombination center density (ρ) and activation energy (ΔE). This is done for each dataset separately, and then by combining dose–response and fading misfits to yield more precise ρ and ΔE values consistent with both experiments. Finally, these values are used to estimate the characteristic dose (D0) of samples. This approach produces kinetic parameter values consistent with comparable studies and results in expected fractional saturation differences between samples.

Thermoluminescence dose-response of synthesized and doped hydroxyapatite: effect of formed crystal phases.

In this research work, pure and doped hydroxyapatite samples were synthesized using hydrolysis and hydrothermal methods to produce powder material. The crystal structure was carried out by producing data using the X-ray diffraction system and the Rietveld method using material analysis using diffraction software. Then the sample was irradiated with different radiation absorbed doses, and their thermoluminescence response was investigated from the dosimetry point of view. The results showed that the synthesis method, doping, and annealing temperature could significantly affect the crystal structure and thermoluminescence dosimetry response of hydroxyapatite samples, consequently. The results showed that the high-temperature annealing process and dopant could lead to the formation of the β-TCP crystal phase during or after the synthesis of hydroxyapatite, and the percentage of this formed phase increased when raising the temperature, and finally led to increase in the thermoluminescence response.

Thermoluminescence Sensitization of Phyllite Natural Rock

A sensitization procedure is used to enhance the thermoluminescence (TL) sensitivity of phyllite to emit radiation. Phyllite is a type of foliated metamorphic rock made from slate. This study examines naturally grown phyllite rock, which had not been previously studied. Using a Thermo 3500 manual reader, the TL sensitivity of phyllite as a function of dosage was measured. The doses required to perform this study were administered using a 60Co source. The statistical regression test of the data had a significance level of p < 0.05. The study also included thermal and pre-dose effects. Using the sensitization procedure, the nonlinearity in TL dose–response was removed, and the sensitivity was increased 44 times that of its original value. The fading study showed a dependence on the test dose. According to the obtained results, the combination of linear dose–response and high sensitivity to gamma radiation makes phyllite an important rock for dating and retrospective dosimetry.

Thermoluminescence properties and kinetic parameters of β-irradiated Turkish slate stone

The current study includes a detailed investigation of the thermoluminescence (TL) characteristics and kinetic analysis of beta-irradiated slate stone from Muğla, Turkey. The heating treatment above 400 °C enhanced the visible TL intensity of the maxima, but the trap system is significantly modified with thermal annealing at temperatures higher than 700 °C. The structural, morphological, and chemical analyses of the samples were verified by X-ray diffraction, scanning electron microscope equipped with energy dispersive X-ray spectroscopy, and atomic absorption spectroscopy techniques, respectively. The TL dosimetric parameters of annealed slate stone including TL glow curves, reusability, fading characteristics, dose response, and heating rate behavior have been studied in detail. There are four apparent TL maxima in the glow curves for both non-annealed and annealed powdered samples, while the natural emission has shown a presence of 395 °C TL maximum as a form of spurious signal that was observed within a few hours during the storage time analysis as well. The material has proven to have very good reusability within the confidence interval (less than ± 5%). A linear response in the dose range of 0.1–103 Gy was achieved when the peak maximum at 258 °C is examined. The kinetic analysis was achieved using TM-Tstop, initial rise, and computing glow curve deconvolution methods. The TL glow curve of the beta-irradiated slate stone annealed at 700 °C consisted of twelve overlapping TL peaks by following first- and general order kinetics.

Experimental measurements confirm decreased supralinearity in the thermoluminescence of beta/gamma irradiated LiF:Mg,Ti (TLD-100) following 3.6 eV and 5 eV optical excitation

Photon excitation at selected energies following beta/gamma irradiation is found to significantly reduce the supralinearity of the thermoluminescence dose response of composite peak 5 in LiF:Mg,Ti (TLD-100). Following a dose of 100 Gy, photon excitation at an energy of 5 eV and fluence of 1.3 × 1018 ph cm−2 reduces the normalized TL efficiency from 2.8 to 1.9 and at 400 Gy from 3.5 to 2.7. Excitation by photons of energy 3.65 eV (1019 ph cm−2) reduces the normalized efficiency of glow peak 5a (a low temperature satellite of peak 5) at 100 Gy from 2.9 to a value of 0.95 thereby resulting in a linear dose response. The high values of dose of 100 Gy and 400 Gy well beyond the normal dose range of clinical radiation therapy were chosen for demonstrative purposes in order to evaluate the likelihood of success of the proposed technique. Additional experiments are underway to determine the photon levels of fluence, which will result in a linear dose response for both glow peaks 5, and 5a in the range of doses 1-30 Gy of interest to radiotherapy and intraoperative electron therapy.