Thermoluminescence Intensity Research Articles

Undoped and Eu doped LaCa₄O(BO₃)₃ phosphors: Thermoluminescence characteristics with a focus on kinetic parameters, anomalous heating rate, and dose response

The thermoluminescence (TL) properties of LaCa₄O(BO₃)₃ (LACOB) phosphors, both undoped and doped with 0.5 % Eu³⁺, were synthesized using a microwave-assisted sol-gel method and analysed under beta irradiation doses ranging from 0.1 Gy to 700 Gy. The TL glow curves revealed prominent peaks at 100 °C and 285 °C for the Eu-doped sample. Activation energy values were calculated using the Hoogenstraaten and Booth-Bohun-Parfianovitch methods, yielding 1.52 eV and 1.48 eV for the undoped sample, and 2.07 eV and 2.01 eV for the Eu-doped sample, respectively. Eu³⁺ ions introduced deeper traps and enhanced the thermal stability of the material. Anomalous increases in TL intensity with rising heating rates were observed, deviating from typical thermal quenching behaviour; this phenomenon was explained using a semi-localized transition (SLT) model. The TL reusability measurements demonstrated a standard deviation of less than 5 %, indicating consistent and reliable performance across multiple cycles. The TL glow curve deconvolution identified six distinct peaks in the undoped sample, while the Eu-doped sample showed a more complex trap structure with eight peaks, indicating the introduction of additional or modified trapping sites by Eu doping. The figure of merit (FOM) values obtained from the deconvolution analysis were all below 2.5 %, indicating a good fit between the observed and fitted TL signals. These findings suggest that Eu³⁺-doped LACOB is a robust material for radiation dosimetry, with its enhanced sensitivity, stability, and versatility across various dosimetric applications.

Liquid nitrogen temperature to 700 K Bi3+ thermoluminescence: Toward wide-temperature-range light dosimeters for versatile anti-counterfeiting, information storage, and x-ray imaging

Discovering light dosimeters that can function effectively from liquid nitrogen temperature to 700 K presents significant challenges. Such dosimeters facilitate a range of cutting-edge applications, including anti-counterfeiting measures at low temperature for cryo-preservation. To facilitate such discovery, stacked vacuum referred binding energy diagrams for the LiYGeO4 cluster of crystals have been first constructed. They offer a robust method for controlling both electron and hole trapping depth in the LiYGeO4 cluster of crystals. Wide temperature shifting of Bi2+ and Eu2+ thermoluminescence (TL) glow bands emerges from 200 to 500 K for LiYxLu1-xGeO4:0.01Bi3+ and LiYxLu1-xGeO4:0.01Bi3+, 0.001Eu3+, by changing x, facilitating conduction band tailoring. Wide temperature shifting of Bi4+ TL glow bands emerges from 300 to 700 K for LiYGezSi1-zO4:0.01Bi3+, by tuning z, facilitating valence band tailoring. TL glow band peaks near 135, 185, 232, and 311 K emerge in LiyNa1-yYGeO4: 0.001Bi3+. Particularly, the discovered Bi3+ or/and lanthanide modified LiYGeO4 cluster of crystals exhibit superior charge carrier storage capacity and minimal TL fading properties. For instance, the ratio of TL intensity of the optimized LiYGe0.75Si0.25O4:0.001Bi3+ to that of industrial BaFBr(I):Eu2+ is as high as ∼4. Interestingly, imaging of intense optically driven Bi3+ ultraviolet-A (UVA) luminescence has been validated in 254 nm energized LiY0.25Lu0.75GeO4:0.01Bi3+ with a 100 lux white LED illumination. Together with ZnS:Mn2+, LiTaO3:Bi3+, Sm3+, and Cs2ZrCl6:Sb3+ perovskites, the realization of wide range liquid nitrogen temperature to 700 K Bi3+ thermoluminescence in Bi3+ or/and lanthanide modified LiYGeO4 cluster of crystals with superior charge carrier storage capacity offers promising use for versatile anti-counterfeiting, information storage, and delayed x-ray imaging purposes.

Persistence luminescence and thermoluminescence of 260 nm UVC irradiated mixed-phase (BaAl2O4 - BaAl12O19) barium aluminate

Persistence luminescence (PerL) and thermoluminescence (TL) of BaAl2O4 - BaAl12O19 mixed phase compound under 260 nm UVC irradiation are studied. The sample shows PerL for more than 1 hour post irradiation. TL glow curves of the sample recorded at 1 oC/s following irradiation to UVC radiation shows a composite glow peak between 30 and 230 oC. The TL intensity is found to be affected by thermal quenching. The activation energy for thermal quenching is estimated to be W=0.85±0.12 eV. A Tm-Tstop analysis reveals that the TL glow peak is composed of multiple first order components. The activation energy associated with the electron traps are found to vary from 0.66 to 1.70 eV. The density of traps is high between 0.60 and 1.20 eV. Due to presence of continuous distribution of electron traps, there is an excellent scope of developing colour tuneable persistence luminescence phosphor using mixed phase barium aluminate.

Thermoluminescence (TL) properties of Eu3+ incorporated with CaB4O7 phosphors prepared by solution-combustion process

The solution-combustion approach was used to create CaB4O7:Eu3+phosphors using Ba (NO3)2, Eu (NO3)3·5H2O, H3BO3, NH3(ON)H2, and NH4NO3 as source materials. We investigated the thermoluminescence (TL) characteristics of beta (β)-irradiated CaB4O7:Eu3+. When the TL intensity was evaluated at different dosages of β, it rose with the dose. Changes in peak temperature were observed because of the investigation of the effects of varying heating rates on TL glow curves. Moreover, the positions of the peak temperature and the TL intensity did not change when the same sample was measured again, suggesting that the sample was stable. Additionally, the study calculated several kinetic parameters, including activation energy (E), frequency factor (s), and geometrical factor (μg), for distinct TL glow curves. Through geometric analysis of TL glow peaks, the study determined activation energies and kinetic orders, enabling the calculation of the frequency factor. The findings highlight the suitability of the prepared phosphor for dosimetry and provide insights into trap characteristics crucial for continuous illumination at room temperature. The study also emphasises the importance of optimising trap depth for prolonged afterglow, shedding light on the interplay between trap energies and luminescence characteristics. These findings deepen our comprehension of phosphor behavior and open the door to better dosimetry applications.

Light-induced fading effects on TL and OSL signals and feasibility of dose re-assessment with PTTL signals in BeO dosimeters

Abstract This study aims to investigate both light-induced fading effects on thermoluminescence (TL) and optically stimulated luminescence (OSL) signals under three different light sources (fluorescent, UV-254 and daylight) and dose reassessment with phototransferred TL (PTTL) signals in Beryllium oxide dosimeters. TL and OSL signals were deconvoluted for each light source. Accordingly, variations in the maximum peak temperature, activation energy, peak area value for the TL signal, and intensity and lifetime values for the OSL signal were monitored. Each peak, OSL component, and total area value exhibited different behaviors depending on the light source. Considering the total area condition, the TL intensity decreased by ∼90%, ∼80%, and ∼70% in UV-254, daylight, and fluorescent light exposure, respectively, at the end of the 120 min. On the other hand, the OSL total area intensity faded quickly for both UV-254 and daylight, while it decreased by ∼45% for fluorescent light. According to these results, regardless of TL and OSL measurements, the dosimeters should be kept primarily away from daylight and fluorescent light after irradiation, instead of UV-254, which is rarely encountered in daily life. The feasibility of dose reassessment using PTTL signals under UV-254 light was investigated within a wide dose range from 0.1 to 128 Gy. It is feasible to reassess doses between 0.5 and 32 Gy considering the total area intensity of PTTL signals. In conclusion, PTTL signals can be easily used in fields of the order of Gy, such as in reevaluating doses in radiotherapy applications.

Enhanced OSL emission from α- Al2O3 produced in the presence of halloysite nanocrystals

Aluminum oxide (Al2O3) compounds are extensively used in ionizing radiation dosimetry due to their high sensitivity when doped with carbon. However, their production is difficult and expensive, leading to much research on alternative ways to increase its sensitivity. This paper proposes a seed-mediated synthesis of α-Al2O3 by the combustion method with halloysite nanocrystals as seeds, which also have the ability to scavenge heavy metal ions. The dosimetric features were studied by radioluminescence (RL), thermoluminescence (TL), and optically stimulated luminescence (OSL). Scanning electron microscopy images and X-ray diffraction patterns pointed to the halloysite nanotubes (HNT) acting as heterogeneous nucleation seeds, and as adsorber centers for the chromium ions (Cr3+), as evidenced by the decreased crystallite size and Cr3+ RL emission. Decreased TL intensity upon increasing HNT content in addition to the RL data suggested that the Cr3+ ions strongly participate in the TL emission process as a luminescent center. Remarkable 6-fold enhanced OSL area intensity and 69-fold OSL initial intensity enhancement were registered from the samples seed-mediated by HNT, revealing that, by scavenging Cr3+, the HNT eliminated a luminescent center that competes with the OSL emission. Therefore, HNTs are promising nanomaterials to enhance the sensitivity of Al2O3 dosimeters with potential application in medical physics, where a decrease in the density of concurrent luminescent centers and an increase in OSL intensity were evidenced by the presence of HNT in Al2O3.

Exploring γ and UV irradiation responses on thermoluminescence and optical thermometry studies on Y4Al2O9:Ho3+ nanophosphor

A series of green emitting Ho3+ (1–9 mol%) doped Y4Al2O9 nanophosphors (NPs) are synthesized via solution combustion technique. Photoluminescence (PL) studies shows emission peaks recorded at ∼ 522 nm (5F3→5I8), 545 (5F4, 5S2→5I8), 659 (5F5→5I8) and 730 (5F4→5I7) upon excited at 460 nm wavelength. With a tremendous potential for application in white light-emitting diodes (w-LEDs), the phosphors show a bright green emission under 460 nm excitation. They also have a notable activation energy (0.31 eV), high color purity (98.2 %), and a remarkable quantum yield (87.1 %). Most astonishingly, even at temperatures as high as 420 K, YAO:5Ho3+nanoparticles retain 88.9 % of their initial fluorescence intensity. Using the fluorescence intensity ratio (FIR) method, the temperature sensing potential is also investigated. Thermoluminescence (TL) glow curves of γ (1 kGy) and UV (1 h) irradiated YAO:Ho3+(1–9 mol%) NPs exhibit two glow curves and highest intensity is recorded for YAO:5Ho3+NPs. TL characteristics of 5 mol% Ho3+ doped YAO NPs are subjected to γ (1 Gy-5 kGy) and UV (0.25–6 h) irradiation. Two glow curves recorded at 475 K (major peak) and 567 K (shouldered peak) for γ irradiation. However, for UV irradiation two glow curves at 478 K (major peak) and 575 K (shouldered peak) are recorded utilizing a 5 °C per minute heating rate. TL intensity varies with γ and UV exposure is recorded for optimized NPs and major glow peaks showcase linear response for both γ and UV irradiations, indicating that the prepared phosphor can be used in TL personal dosimetry. Furthermore, compared to γ-irradiated phosphor, UV-irradiated phosphor shows greater fading. The overall results clearly demonstrate that the optimized phosphor has proven to be an outstanding candidate for multifunctional applications.

Non-empirical peak shape methods based on the physical model of the one trap one recombination center model

Any experimental Thermoluminescent (TL) glow-peak contains the activation energy information of its corresponding energy level within the band gap in insulating materials. The theory of peak shape methods (PSM) correlates the macroscopic geometrical characteristics of a single TL peak with activation energy of the level responsible for the TL peak by assuming that the area under a TL peak can be approximated by the area of a triangle. In this way the geometrical characteristics becomes the measure of the activation energy. In the present work new PSM expressions are derived, which are not empirical as the existing ones but are based of the physical model of one trap one recombination (OTOR) center. Three cases are considered. (I) Delocalized OTOR for re-trapping probability smaller than the recombination probability. (II) Delocalized OTOR for re-trapping probability greater than recombination probability. (III) Localized transitions OTOR model. The system of differential equations of each case model were solved analytically using the Lambert W function (or equivalently the Wright ω function). Then the resulted analytical expressions of TL intensity as a function of temperature were used to derive new PSM. The new PSM from all cases are formally exactly the same, having, however, strong differentiation in their coefficients. The functionality of the new expressions is tested and its comparison with pre-existing PSM is performed.

Thermoluminescence and ATR-FTIR study of UVC-irradiated low-density polyethylene (LDPE) food packaging

This research aims to study the effects of ultraviolet C (UVC) radiation on low-density polyethylene (LDPE) food packaging. Main objectives include evaluating LDPE degradation and detecting UVC radiation using thermoluminescent dosimeters (TLDs) placed under LDPE samples. Results confirm accurate UVC detection after one hour of exposure, providing a useful tool for optimize food treatment procedures.ATR-FTIR spectroscopy analysis revealed subtle alterations (<8 % transmittance relative) in UVC-irradiated LDPE samples, including possible CH breakage (2910 and 2848 cm−1) and potential CC bond vibrations (1470 cm−1), among others. However, observed variations may stem from LDPE properties rather than entirely from UVC radiation. A comparative study of UVC-induced thermoluminescence (TL) emissions provided insights into various TLDs materials. TL kinetic analysis, using computerised glow curve deconvolution (CGCD) method, unveiled trap charge activation due to UVC exposure, including partial ionization, bleaching effect and photo-transfer (PTTL) processes. LDPE samples amplified UVC-TL responses, revealing intensity differences between the TLDs attributed to the PTTL process, accentuated by the lack of an annealing treatment. Additionally, chemical composition of the TL detectors such as, type, concentration, number, oxidation states and ionic radii of their dopants may influence UVC-TL response. Consequently, TL intensity ratios follow as: GR-200 (LiF: Mg, Cu, P) > TLD-100 (LiF: Ti, Mg) > TLD-400 (CaF2: Mn) > TLD-200 (CaF2: Dy). Thus, GR-200 detects ionizing radiation but cannot distinguish between ionizing and non-ionizing UVC radiation, while TLD-100 has limited effectiveness as a UVC radiation detector. In contrast, TLD-400 is suitable for detecting UVC radiation and TLD-200 emerges as the most favorable UVC detector, showing consistent response levels and minimal PTTL effect placed under the LDPE samples without the need of a thermal annealing treatment that makes the TLD-200 to be reusable in a low-cost measurement protocol.

Photoluminescence and beta-ray irradiation induced thermoluminescence of Er(III) doped tungstate double perovskite

A luminescent double perovskite Ca3WO6 doped with Er3+ was successfully synthesized via traditional solid-state reaction. Structural analysis was performed through X-ray diffraction (XRD) patterns utilizing Rietveld refinement. When excited at 380 nm, the Ca3WO6:Er3+ phosphors displayed green spectral emission, corresponds to 2H11/2, 4S3/2 to 4I15/2 transitions of Er3+. The influence of Er3+ concentrations on photoluminescence (PL) intensity and concentration quenching was discussed, ascribing multipolar interaction as a cause of intensity quenching. The temperature-dependent PL analysis revealed the phosphor's excellent thermal stability, retaining approximately 79.6 % of its PL intensity at 150 °C. Furthermore, the Ca3WO6:Er3+ phosphors exhibited high-quality thermoluminescence (TL) after beta irradiation. The impact of Er3+ concentrations and beta dose on TL intensity was investigated comprehensively. The reproducibility of the phosphor was checked after several TL readouts. The various heating rate (VHR) experiments were conducted to examine the effect of HR and to determine the trapping parameters.

Impact of sample preparation temperature on Li and Ce co-doped MgB4O7 dosimetry performance: A plausible scenario for controlling defect clustering

MgB4O7 co-doped with Ce and Li has been recognized as a promising dosimetric material for spatially-resolved optically stimulated luminescence (OSL) measurements. Nevertheless, conflicting information exists in the literature regarding its dosimetric characteristics. These include discrepancies in fading, the proportion of shallow traps, the range of linear dose response, and a notable absence of direct sensitivity comparisons. These discrepancies are likely attributed to variations in the synthesis methods utilized to produce this material. As part of our research initiative aiming at elucidating the influence of synthesis on the luminescence properties, we are examining in this contribution a single parameter – specifically, the sample preparation temperature – and assessing its impact on the luminescence properties. For the first time, we identified a correlation between the width of the thermoluminescence (TL) glow curves, the TL, optically stimulated luminescence (OSL), and radioluminescence (RL) intensities, as well as the fading characteristics over time and annealing temperature. We show that annealing at higher temperature leads to narrowing of the main TL peak (c.a. 240 °C at 5 °C/s heating rate) compared with samples prepared at lower temperatures, which in turn leads to a decrease in the integrated TL intensity of that peak. Despite exhibiting lower intensity, samples prepared at temperatures above 800 °C show less than 10 % TL/OSL fading over 60 days. Our measurements suggest an involvement of clustered defects for the samples prepared at 600 °C, with a shift towards a scenario of delocalized transitions in samples prepared at higher temperatures.

Thermally stable luminescence and dosimetric features of Ho(III) activated tungstate double perovskite

Luminescent efficient tungstate double perovskites Ca3WO6 doped with Ho3+ were synthesized via the solid-state reaction at 1200 C°. The resulting phosphors were analyzed using Rietveld refinement of X-ray diffraction (XRD) data, confirming a monoclinic crystal structure with crystallite sizes ranging between 50 and 55 nm. Optical bandgap determination was facilitated by diffusion reflectance spectra (DRS). Fourier transform infrared (FTIR) studies were conducted to identify functional group vibrations. The optical excitation of the Ca3WO6:Ho3+ phosphors under different excitation conditions resulted in intense green photoluminescence (PL) emission at 545 nm, indicative of the 5F4–5I8 transition of Ho3+ ions. Thermal stability assessment of Ca3WO6:1 % Ho3+ phosphor under blue excitation (454 nm) revealed good thermally stable luminescence about 85.32 % at LED working temperature (150 °C). PL decay studies were conducted to analyze fluorescent behaviour, wherein by means of PL decay lifetime, the PL quantum efficiency of Ca3WO6:1 % Ho3+ phosphor is computed to be 91.1 %. The CIE color coordinates of the phosphors being investigated reside within the green spectral region, with a calculated color purity of 93.25 % observed for Ca3WO6:1%Ho3+. Furthermore, the phosphors under study exhibited high-quality thermoluminescence (TL) after beta irradiation. The detailed TL characterization conducted to assess dosimetric properties. The impact of Ho3+ concentrations and beta dose on TL intensity are two major aspects that have been investigated in detail. TL fading experiments were performed to determine dose storage capacity over a month after beta irradiation. Additionally, the various heating rate (VHR) experiments are conducted to determine the TL kinetic parameters. Besides, the glow curve deconvolution (GCD) for trap parameter determination is also applied, where the results obtained are comparable with the VHR results.

Gamma irradiated Er3+ ions doped Li2O–BaO–B2O3–P2O5 glasses: Structural, optical, and thermoluminescence glow curve analysis

Lithium barium borophosphate glasses doped with Er3+ rare earth ions are reported in terms of their physical, optical, structural, and thermoluminescence (TL) properties in this study. The melt quenching method was used to synthesize the glasses with varying concentration of the dopant (0.0, 0.2, 0.4 0.6, 0.8 and 1.0 mol%). A thorough analysis of physical characteristics, including their variation with erbium oxide, has been conducted. The amorphous phase of the as-quenched samples has been validated through X-ray diffraction patterns, while Fourier transform infrared spectroscopy confirmed the existence of different structural groups. UV–Vis–NIR spectroscopy at wavelengths ranging from 200 to 1100 nm has been utilized to investigate various optical properties. In the gamma dose range of 50 Gy to 10 kGy, the glass sample with 0.6 mol% of erbium concentration (LBPEr0.6) showed the maximum integrated TL intensity with an optimized heating rate of 5 °C/s and annealing temperature of 400 °C. The deconvolution of TL glow curves was done using the R-package “tgcd: Thermoluminescence Glow Curve Deconvolution" by employing the Kitis general order kinetics model. Chen's peak shape approach has been used to calculate the trapping parameters, including order of kinetics (b), shape factor (μg), frequency factor (s), and activation energy (E). The ideal thermoluminescence dosimeter characteristics showed that LBPEr0.6 glass has outstanding linearity, excellent sensitivity, minimal fading and good reproducibility over six cycles.

Thermoluminescence response of carbon ion beam irradiated LiCaAlF6: Tb phosphor

Accurate measurement of the dose delivered to patients is crucial in any radiation therapy, including C ion beam radiotherapy, to ensure effective treatment and minimize the risk of damage to healthy tissues. The accessibility of thermoluminescence (TL) - based materials for carbon ion beam dosimetry continues to be constrained. With the aim of this, an investigation has been done to study the TL properties of the Terbium (Tb) doped LiCaAlF6 phosphor following irradiation with C ion beam. The LiCaAlF6: Tb phosphor has been synthesized using melting method in argon gas atmosphere. TL glow curves has been analyzed on exposure to carbon ion beams at energies of 85 MeV and 50 MeV within the fluence range of 109 - 1012 ions/cm2. The TRIM code, relying on Monte Carlo simulation, has been employed to compute parameters such as absorbed dose, ion range, and energy loss. The Tb-doped LiCaAlF6 phosphor exhibits a glow curve structure with distinctly resolved peaks at 130 °C and 325 °C. Notably, the TL intensity has been significantly increased by 105 times than that of undoped LiCaAlF6. This enhancement is attributed to the generation of a high density of Tb-associated defects within the energy band gap. The TL enhancement has been elucidated based on charge compensation mechanism. Further, TL glow curve shape and structure remain consistent across different energies, i.e., 85 and 50 MeV C ion beams, indicating an energy-independent behavior of this phosphor. Nevertheless, the TL intensity at 85 MeV is higher compared to that at 50 MeV. Detailed dosimetry properties have been investigated for 85 MeV C ion beams within the fluence range 2x109-5x1012 ions/cm2. The phosphor exhibits a sublinear dependence against dose for the studied fluence range with no discernible shift in peak position. The favorable outcomes include low fading during the initial days of storage time and batch homogeneity. TL glow curve analysis indicate the formation of trapping level in the range of 0.90–1.72eV within the band gap of the phosphor which are responsible for TL process. The phosphor's simple glow curve structure, minimal fading, consistent batch homogeneity and high stability of the glow curve suggest that the material can be explored for C ion beam dosimetry application.

Thermoluminescence characterization of flooring tiles from Malaysia for potential use in retrospective dosimetry

In the event of natural disasters or technical malfunctions at nuclear sites, the surrounding media, including individuals, may be subject to unforeseen radiation exposure. Thus, it is not possible to determine the precise level of radiation exposure that each person has received in this scenario. To handle such a problem, the use of retrospective dosimetry can offer an accurate evaluation of the radiation dose acquired as a result of such incidents. This information enables the development of suitable remedial actions. Normally, in the region that has been impacted, several artifacts can serve as natural dosimeters. The study involved the utilization of locally available seven different brands of flooring tiles in Malaysia for the possibility of being used in retrospective dosimetry through exposures to 60Co gamma-rays within a range of 10–200 Gy. To understand the luminescence features of this material, a convenient thermoluminescence (TL) technique has been employed. The dosimetric features of the samples were investigated, including their effective atomic numbers (Zeff), reproducibility, glow curve, dose response, sensitivity, linearity index, energy dependency and fading, which is representative of the usual TL method. Additionally, by analyzing the glow curves of the irradiated samples together with the peak shape method and the initial rise methods, several kinetic parameters, including the kinetic orders (b), activation energy (E) or trap depth, frequency factor (s) or escape probability, and trap lifetime (τ) were calculated. Different kinds of tiles exhibit distinct scenarios in terms of kinetic characteristics. T1 sample exhibits the highest degree of sensitivity and a highly linear dose response among the tile samples that were evaluated. Also, T1, T3, and T5 samples show minimal loss of TL intensity (∼38–39%) one year after irradiation, making them ideal for use as a retrospective dosimeter.

A Study toward the Model Independence of Various Heating Rates Method in Thermoluminescence Glow Curve Analysis

This study analyzes thermoluminescence (TL) glow curves simulated in general order kinetics (GOK), one trap one recombination center (OTOR), and non‐interactive multi‐trap system (NMTS) models using various heating rates (VHR) method in linear heating scheme to extract the activation energy. A theoretical analysis to determine activation energy from TL curves using OTOR and NMTS models in an iterative manner, where the TL intensity is determined by using the Lambert‐W function, is proposed with its limitations. It is established that the activation energies in OTOR and NMTS models consist of the relevant GOK term and a respective correction term. Systematic analysis is carried out to study the improvement of the accuracy of activation energy derived from OTOR and NMTS model TL curves over the GOK model calculation. A quantitative analysis of the quasi‐equilibrium (QE) approximations is carried out for choosing appropriate system parameters. The validity of QE conditions are determined by studying variations of full width at half maximum as well as area under the curve as a function of heating rate. The present method is applied on some experimental data to estimate activation energies. This investigation reveals that the activation energy derived in VHR method has negligible dependence on the underlying theoretical models, i.e., the activation energy derived from GOK model calculation is significantly accurate for experimental scenario.

Usability of sand samples in TL Radiation Dosimetry.

This study investigated natural sand thermoluminescence (TL) response as a possible option for retrospective high-dose gamma dosimetry. The natural sand under investigation was collected from six locations with selection criteria for sampling sites covering the highest probability of exposure to unexpected radiation on the Egyptian coast. Dose-response, glow curve, chemical composition, linearity, and fading rate for different sand samples were studied. Energy Dispersive X-ray Spectroscopy (EDX) analysis revealed differences in chemical composition among the various geological sites, leading to variations in TL glow curve intensity. Sand samples collected from Ras Sedr, Taba, Suez, and Enshas showed similar TL patterns, although with different TL intensities. Beach sands of Matrouh and North Coastal with a high calcite content did not show a clear linear response to the TL technique, in the dose range of 10Gy up to 30kGy. The results show that most sand samples are suitable as a radiation dosimeter at accidental levels of exposure. It is proposed here that for high-dose gamma dosimetry with doses ranging from 3 to 10kGy, a single calibration factor might be enough for TL measurements using sand samples. However, proper calibration might allow dose assessment for doses even up to 30kGy. Most of the investigated sand samples had nearly stable fading rates after seven days of storage. The Ras Sedr sands sample was the most reliable for retrospective dose reconstruction.

Thermoluminescence studies of a Gothic church in Świebodzin from Silesia in Poland

The paper presents thermoluminescence (TL) studies that aim to establish the possibility of using such analysis to determine the date of the construction, transformation and/or rebuilding of a historical church. The determination of the age of building structures using the form of absolute dating that is now used by architects and archeologists is difficult and complex. A relatively large error of estimation can be observed in archeological studies. In the case of samples from the Middle Ages, such errors are not acceptable. The authors attempted to develop an alternative spectroscopic TL method for such studies, and proposed that the composition of bricks should be measured using X-ray diffraction, electron microscopy (EM) and TL spectra. The bricks for the testing were taken from internal walls and the walls in the attics of churches, i.e. from places built during the last stage of construction works. The TL measurements were made using x-ray and β source excitation within the temperature range of 25–500°C. Two different sizes of grains were studied: small (∼0.1 mm) and large (∼0.5 mm). A gothic church in Świebodzin from 1555, which has a well-known history of its construction, was selected for the investigations. Due to the fact that this church is 326 years younger than the two churches evaluated and described in [1], the composition of its bricks could be different. Therefore, the authors decided to compare the XRD data, EM results and TL spectra for bricks taken from all three churches. The intensities of the TL and the integrated TL intensities were determined. The measurement results are important for creating a relationship between the TL intensity and the date a building object was constructed. Moreover, thanks to this it was possible to verify the construction date of Saski Palace in Warsaw.

Effect of IRSL-BLSL-TSL reading modes combination on thermoluminescence (TL) response of BeO dosimeter.

The ultimate goal of this work is the study of the effect of luminescence stimulations and signals reading modes combinations on the thermoluminescence intensity and glow curve behaviour for the same X-ray irradiation dose. Three interesting stimulating and reading modes are considered, namely, infrared stimulated luminescence (IRSL), blue light-emitting diode stimulated luminescence (BLSL) and thermally stimulated luminescence (TSL). The studied stimulation and reading modes combination protocols are (Protocol 1) IRSL-TSL, (Protocol 2) IRSL-BLSL-TSL and (Protocol 3) BLSL-IRSL-TSL. Experiments are performed on beryllium oxide (BeO) dosimeter. Results demonstrate well that the combination of reading modes have direct impact on the TL signal in terms of intensity and glow curve shape. It was also found that when reading modes are correctly combined, particularly when IRSL is applied first, then BLSL and TL, it is possible to collect two or more exploitable signals of different stimulation types for the same irradiation that can be used for different purposes and final applications.

Exploring beta irradiation responses in Sr2+-Doped hydroxyapatite: A thermoluminescence study

This research investigates the structural and thermoluminescence (TL) properties of Sr2+-doped Ca5(PO4)3OH (HAp) phosphors. X-ray diffraction (XRD) analysis confirms that HAp has a hexagonal structure with a P63/m space group. The TL behaviour of HAp:Sr2+ phosphors is examined under beta irradiation in the temperature range of 25–500 °C. The study reveals three TL glow peaks at temperatures of 75, 212, and 296 °C. Investigation of TL responses across heating rates (HR) ranging from 0.1 to 5 °C/s shows that higher HRs result in increased maximum TL peak temperatures and reduced TL intensities. This trend suggests an augmented contribution from non-radiative transitions as the heating rate increases. Importantly, no evidence of thermal quenching is found in the HAp samples. Two different methods, Hoogenstraaten's and Booth-Bohun-Porfianovitch, yield consistent activation energy values of 0.50, 1.22, 1.67 eV, and 0.48, 1.19, 1.63 eV, respectively. Reusability assessments indicate a standard deviation of less than 5 %, confirming the reliability of the materials. Tm−Tstop analysis reveals a continuous distribution of trap levels. TL properties in HAp samples have been comprehensively characterized, contributing not only to enhancing our understanding of their behaviour, but also highlighting their potential applications in various areas. The findings of this study have provided valuable insight into the development of efficient catalysts that are suitable for a variety of applications.