Thermoluminescent Materials Research Articles

Destruction of Doped Lithium Tetraborate under Exposure to Ionizing and Laser Radiation

The results of the study of the degradation of thermoluminescent materials Li2B4O7:Be + Mn and Li2B4O7:Zn + Mn under the effect of radiation (pulsed electron beam) and laser radiation are presented. As a result of exposure to high doses of radiation, the structure of the samples under study partially acquires an amorphous character, while the effect of radiation exposure is manifested in the optical properties in the appearance of green luminescence due to manganese centers in the tetrahedral environment. With subsequent irradiation with a laser at a wavelength of 350 nm, luminescence centers decay due to photochemical oxidation of manganese by the reaction of Mn2+ → Mn3+. It is shown that Li2B4O7:Be + Mn has a lower radiation resistance than Li2B4O7:Zn + Mn.

Thermoluminescence characteristic of CaSO4:Dy on β and γ radiation

The research on the developments of thermoluminescence (TL) material in nano- and microstructure are increasing in recent years. There are many new techniques developed for preparing TL material that aim to improve and investigate the structure, morphology, and TL characteristics. In this study, the TL characteristics of CaSO4 doped with Dysprosium (Dy) were being observed. CaSO4:Dy was performed by co-precipitation method with 0.1 mol% Dy concentration. The obtained sample was irradiated with Cs-137 for gamma source and Sr-90 for beta source with doses of 5, 10, 15, 20 and 25 mGy. After irradiation, the structure, morphology, and TL response were observed by using XRD, SEM, and TLD Reader Harshaw 3500. XRD results showed that the average crystallite size for CaSO4:Dy were 58 nm. But, the presence of dysprosium could not be clearly observed from XRD results. The characterization results from SEM for CaSO4:Dy had shape resembling needle-like crystal. The TL response of CaSO4:Dy was compared from beta and gamma radiation source. TL responses for Cs-137 source were 26.56, 34.09, 51.85, 75.97, and 86.29 nC for 5, 10, 15, 20, and 25 mGy, respectively. Sr-90 source with the same dose obtained TL responses as follows: 35.67, 68.60, 100.87, 121.69, and 179.85 nC. The shapes of the glow curves were almost identical, but these curves had different intensities. The TL response from β-ray source obtained a higher intensity than from γ-ray source because the beta source is a particle with mass so that it will have more interaction than gamma source in TLD material.

Versatility of thermoluminescence materials and radiation dosimetry - A review.

Thermoluminescence (TL) materials exhibit a wide range of applications in different areas such as personal dosimetry, environmental dosimetry, medical research etc. Doping of different rare earth impurities in different hosts is responsible for changing the properties of materials useful for various applications in different fields. These materials can be irradiated by different types of beams such as γ-rays, X-rays, electrons, neutrons etc. Various radiation regimes, as well as their dose-response range, play an important role in thermoluminescence dosimetry. Several TL materials, such as glass, microcrystalline, nanostructured inorganic materials and recently developed materials, are reviewed and described in this article.

OPTICALLY STIMULATED LUMINESCENCE OF LiF:Mg,Cu,P POWDER-INFLUENCE OF THERMAL TREATMENT.

It was recently found that LiF:Mg,Cu,P, which is a very well-known thermoluminescent (TL) material, exhibits also quite substantial optically stimulated luminescence (OSL). In the present work a study on the influence of thermal treatment on the LiF:Mg,Cu,P OSL intensity has been performed. The results revealed that the well-known 'gold standard' of 240°C annealing is not appropriate for OSL measurements. The annealing at lower temperatures produced significantly higher OSL intensity. The highest enhancement of the OSL signal, reaching 95% (compared to the initial signal after standard annealing at 240°C/10 min) was obtained after annealing at about 190-200°C/30 min. The OSL emission spectrum of LiF:Mg,Cu,P was also measured and found to be peaked at 360 nm.

Sonochemical synthesis of green emitting Ca2SiO4:Er3+ nanopowders: Promising applications in optical thermometry and radiation dosimeter

The Er3+-activated Ca2SiO4 nanopowders were fabricated via sonochemical method using Epigallocatechin gallate as a bio-surfactant. The X-ray diffraction results reveal that the prepared nanopowders consist of a single phase monoclinic structure. The energy band gap of the prepared samples was estimated and found in the range 4.95–5.18 eV. The photoluminescence emission spectra exhibit intense peaks centered at ∼517, 551, 613 and 662 nm, which were attributed to 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, 4F9/2 → 4I15/2 and 4F9/2(1) → 4I15/2 transitions of Er3+ ions, respectively. The photoluminescence emission intensity increases up to 5 mol % of Er3+ concentration and later diminishes. The decrement of emission intensity with increasing Er3+ concentration was related to a self-quenching of the concentration. The cause behind the concentration quenching was proposed as a dipole–dipole interaction among Er3+ ions. Photometric characterizations of Er3+-doped Ca2SiO4 nanopowders exhibit green light emission with high color purity indicates the present nanopowders were quite useful in the fabrication of cool light emitting diodes. The sensor sensitivity of the Ca2SiO4:Er3+ (5 mol %) nanopowders was found to be ∼0.0624 K−1 at lower temperature 303 K, suggesting suitability for the optical thermometry application. Further, thermoluminescence properties of the prepared samples were extensively investigated. The activation energy and frequency factor of the prepared nanopowders were estimated and obtained values were good agreement with standard thermoluminescence materials, which specify the suitability of the prepared nanopowders in dosimetry applications. The aforementioned results confirm the synthesized nanopowders exhibit excellent photometric, sensor sensitivity and thermoluminescence properties signifying suitability in solid state lighting, optical thermometry and dosimetry applications.

Application of XANES in gamma dosimetry

The thermoluminescence material, CaSO4:Dy, is widely used for the dosimetry of ionizing radiation due to its high sensitivity, low fading and wide dose range from μGy to few tens of gray. However, its application is limited at high doses due to non-linear and saturation effects. In this paper, X-ray Absorption Near Edge Structure (XANES) studies at the Dy L3-edge have been carried out on CaSO4:Dy discs exposed to gamma doses in the range 0–1000 Gy. The results show an increase in white line in XANES spectra with gamma dose. Structural change in CaSO4:Dy also has been studied using X-Ray Diffraction (XRD) and has found no structural change up to 1000 Gy. The study indicates that XANES can be used as an alternative dosimetry technique and is useful in the evaluation of absorbed dose in the case of accidental exposure to high radiation in a radiation facility or during a radiological accident.

Commercial kitchenware glass as a potential thermoluminescent media for retrospective dosimetry

Study has been made of the thermoluminescence (TL) yield of various glass-based commercial kitchenware (Reko-China, Skoja-France, Godis-China, Glass Tum-Malaysia, Lodrat-France). Interest focuses on their potential for retrospective dosimetry. Use was made of a60Co gamma-ray irradiator, delivering doses in the range 2–10 Gy. Results for the various media show all the glassware brands to yield linearity of response against dose, with a lower limit of detection of ∼0.06 and ∼0.08 Gy for loose and compact powdered samples. Among all of the brands under study, the Lodrat glassware provides the greatest sensitivity, at 6.0 E+02 nC g−1 Gy−1 and 1.5E+03 nC g−1 Gy−1 for compact- and loose-powdered forms respectively. This is sufficiently sensitive to allow its use as a TL material for accident dosimetry (2 Gy being the threshold dose for the onset of a number of deterministic biological effects, including skin erythema and sterility). Energy Dispersive X-ray (EDX) analyses have been conducted, showing the presence of a number of impurities (including C, O, Na, Mg, Al, Si, Ca and Br). Fading of the irradiated glasses show the amount of better than 3% and 5% of the stored energy for both loose and compact powdered samples within 9 days post irradiation. As such, commercial kitchenware glass has the potential to act as relatively good TL material for gamma radiation dosimetry at accident levels. This is the first endeavour reporting the TL properties of low cost commercial kitchenware glasses for gamma-ray doses in the few Gy range, literature existing for doses from 8 Gy to 200 Gy.

Trap level analysis of Ce3+ and Sm3+ in Li6Y(BO3)3

Abstract The polycrystalline compounds of Li6Y(BO3)3: Ce3+ and Sm3+ co-doped polycrystalline samples were prepared by using standard solid state reaction method. The energy levels of the doped lanthanide ions (Ce3+ and Sm3+) in the borate host materials were investigated by Thermoluminescence (TL) glow peak analysis. The co-doped samples, exhibits the TL peak at higher temperature region around 511 K whereas the Ce3+ individually doped sample has peak around 433 K. The X-ray excited emission spectra were carried out for all the prepared samples and found the characteristic emission bands. The trap depths (E) were calculated by using several standard methods, namely peak shape method or chen's (PS), variable heating rate (VHR), initial rise (IR) and computerized glow curve deconvolution (CGCD). The mean activation energy of the co-doped samples found to be 1.21 (0.07±) eV and the frequency factor around 1.38 × 1011 Sec−1. The calculated trap depths and the predicted energy level values were compared and found in good agreement. This primarily results suggest that the energy level scheme can help in the development of new TL materials suitable in dosimetry.

Energy-absorption buildup factors of some fluorides and sulfates: thermoluminescent dosimetric materials

Gamma ray energy-absorption buildup factors were computed, using the five-parameter Geometric Progression fitting formula and the ANSI/ANS-6.4.3 report, for some fluorides and sulfates in the energy range 0.015−15 MeV, and for penetration depths up to 40 mfp. The generated energy-absorption buildup factors are studied as functions of penetration depth and incident photon energy. At a given penetration depth, the buildup factor first increases, reaching a maximum value, and then decreases with increasing energy. The maximum value of the buildup factor occurs in the energy range 0.15–0.3 MeV. At these energies, Compton scattering is the major photon interaction process, and photoelectric absorption is of relatively little importance, leading to large buildup factors. The results of the present work should be useful in radiation dosimetry, diagnostics and therapy. The tissue equivalence of these materials is also discussed. It is found that lithium fluoride can be effectively used as a tissue equivalent material for cortical bone in the energy region 0.2−2 MeV.

Разрушение легированного тетрабората лития под воздействием радиации и лазерного излучения

AbstractThe results of the study of the degradation of thermoluminescent materials Li_2B_4O_7:Be + Mn and Li_2B_4O_7:Zn + Mn under the effect of radiation (pulsed electron beam) and laser radiation are presented. As a result of exposure to high doses of radiation, the structure of the samples under study partially acquires an amorphous character, while the effect of radiation exposure is manifested in the optical properties in the appearance of green luminescence due to manganese centers in the tetrahedral environment. With subsequent irradiation with a laser at a wavelength of 350 nm, luminescence centers decay due to photochemical oxidation of manganese by the reaction of Mn^2+ → Mn^3+. It is shown that Li_2B_4O_7:Be + Mn has a lower radiation resistance than Li_2B_4O_7:Zn + Mn.

Fine structure in high resolution 4f7–4f65d excitation and emission spectra of X-ray induced Eu2+ centers in LuPO4:Eu sintered ceramics

X-ray induced effects in LuPO4:Eu3+ sintered thermoluminescent material were investigated by absorption and photoluminescence measurements between 20 and 300 K. Evidence for Eu3+→Eu2+ conversion upon exposure to X-rays was obtained as narrow band blue Eu2+ photoluminescence was observed. The low temperature luminescence of Eu2+ ions in X-rayed LuPO4:Eu ceramics showed a unique fine structure with a sharp zero-phonon line at 425.8 nm and well-resolved vibronic structure. Excitation spectra of the Eu2+ luminescence revealed a rich structure in which individual 4f7→ 4f6(7FJ)5d1 zero-phonon lines accompanied by vibronic transitions were identified. A detailed analysis allowed an accurate calculation of the Eu3+-like 4 f6(7FJ) core levels in the 4 f65d1 excited configuration. The 4f6 core splitting is different from that of the 7FJ states for Eu3+ in LuPO4, providing evidence for the role of 4f6–5d interaction on the splitting of the 4f6 configuration. The unique luminescence of Eu2+ with a small Stokes shift and well-determined energies of 4f6(7FJ)5d1 excited states make LuPO4:Eu a model system for testing theoretical models which are presently developed to calculate and predict the energy level structure and Stokes shift of 4fn–4fn−15d1 transitions of lanthanides.

Thermoluminescence of single wall carbon nanotubes synthesized by hydrogen-arc-discharge method

Single Wall Carbon Nanotubes (SWNT) synthesized by the hydrogen-arc-discharge method were tested as thermoluminescent (TL) material and found to be highly resistant to gamma radiation. Gamma irradiation of the as-prepared material with doses between 1 and 20 kGy induced changes on the morphology of the SWNT, such as nanoloops, as observed by Scanning Electron Microscopy. From X-ray diffraction, the as-prepared material shows content of various forms of carbon, including nanotubes, hexagonal carbon (graphite), and rhombohedral carbon too. The full width at half maximum (FWHM) of diffraction peaks remain practically unchanged after irradiation. The glow curves show a single TL peak centered at about 449 K. Because the complex structure of the glow curves, it seems that the TL signal could be produced by a trap distribution instead of a single level of traps. To dilucidate the mechanism responsible of glow curves and the value of activation energy of traps, kinetic parameters like Eeff, ΔE, and s of experimental the glow curves have been analyzed using computerized glow curve deconvolution (CGCD) considering a continuous distribution of trapping levels, peak shape and initial rise methods, as well as heuristic equations. The measured TL dosimetric properties may be summarized as follows: (a) moderate reproducibility of the TL signal (coefficient of variation 24.87%); (b) main peak activation energy of 1.206 eV; (c) threshold dose of ~1 kGy; (d) TL-sensitivity of ~7.0 × 10−4; (e) human bone equivalence, i.e., high-Z material, Zeff = 15 and, (f) wide linear range of TL dose-response in the range 0.170–2.5 kGy.

P100] Calculations of dosimetric parameters from depth dose curve of electron beams, using radiophotoluminescent and thermoluminescent dosimeters

Purpose The aim of this study was to calculate the dosimetric parameters derived from percent depth dose curves by using RPL-GD and TLD-100 detectors for high-energy electron beams. Methods In this study, Monte Carlo simulation code MCNP5 was using to calculate the percent depth dose (PDD) in water phantom for 9, 12, 16 and 20 electron beam energies with utilizing the Radiophotoluminescent (FD-7glass series) and Thermoluminescent (TLD-100) materials. Results We found a good agreement with literature for Monte Carlo calculations parameters derived from the PDD curve such as various ranges R 100 , R 90 , R 80 , R 50 and R p and energies specification such us most probable energy E p , o and mean incident energy E 0 . Conclusion In conclusion, RPL-GD and TLD-100 dosimeters are a very useful detector for routine QA checks for electron therapy [1] .

Comparative study of the TL response of LiF:Mg,Ti and CaSO4:Dy in the clinical electron beams dosimetry applied to total skin irradiation (TSEB) treatments

The commissioning and quality assurance The Total Skin Electron Beam (TSEB) irradiation treatment is based on the AAPM's report 23, which describes the six-dual-field (Standford) technique, and the Hospital Israelita Albert Einstein (HIAE) follows this recommended guidance. The Dosimetric Materials Laboratory of the Instituto de Pesquisas Energéticas e Nucleares (IPEN-LMD) has tradition in research related to thermoluminescent materials and its clinical applications. Thus, aiming to apply the LiF:Mg,Ti, the most common TLD material, and CaSO4:Dy + Teflon produced at IPEN as easy-to-use alternatives to electron beams dosimetry and its parameters applied to TSEB, this paper reports a comparative study of the TL responses of both materials to dose evaluation in TSEB treatments. The TL response of both materials was evaluated in several TSEB parameter tests such as clinical field homogeneity, Monitor Units (MU) calculation, absorbed doses over the reference line and throughout the surface of the skin in a treatment simulation using AldersonRando anthropomorphic phantom. Results show that the field homogeneity measurements remained within ± 8% acceptance limit from AAPM Report 23, little to no energy dependency over the range of 4 o 9 MeV electron beams and, for clinical measurements and MU calculations, both TLDs present compatible results and can be used as alternative tools in TSEB dosimetry.

Thermoluminescence analysis for particle temperature sensing and thermochronometry: Principles and fundamental challenges

Thermoluminescence (TL) has traditionally been used to estimate the depth of trapping centers in luminescence materials and explain the isothermal decay in the case of synthetic dosimeters and natural materials used in luminescence dating. Nevertheless, new fields of application of TL and optically stimulated luminescence (OSL) materials, namely particle temperature sensing and thermochronometry, motivate a need for accurate models for the luminescence processes and estimation of the trapping parameters, in particular activation energy and frequency factor. Although calibration of the TL materials may be possible and recommended in some applications, using for example, microheaters, laser heating or pyroprobes, the procedures can be complicated and time consuming. With TL, however, appropriate models with parameters obtained in laboratory conditions can in principle be used to predict the temperature and time dependence of the stimulation processes in the microsecond to the second timescales (in the case of particle temperature sensing), and in the tens of thousands years (in the case of thermochronometry). In this paper we present the fundamentals of temperature sensing using TL, tracing parallels between the applications in thermochronometry and in particle temperature sensing, and review the main challenges, both fundamental and practical, for the advancement of the technique. Fundamental challenges are the very wide timescales involved in these applications, the need for better TL models, and the inherent time-temperature ambiguity in the Arrhenius equation, in addition to other practical problems. Possible solutions to these challenges and future research directions are discussed.

DETERMINATION OF THE KINETIC PARAMETERS OF BeO THERMOLUMINESCENT SAMPLES USING DIFFERENT METHODS

The objective of this work was to determine the kinetic parameters of BeO thermoluminescent (TL) samples. The knowledge of the kinetic parameters is important for the general description of the physical characteristics of a thermoluminescent material. Using a linear heating rate of 5K/s -1 , the BeO peak temperatures obtained were (474.7 ± 1.2) K and (620.5 ± 1.2) K, respectively, for the first and second TL peaks. The peak shape and the glow curve area measurement methods and the Urbach formula have been used for the trap parameter determination. A kinetic order of about two was determined for the first peak, whereas the second peak followed the first-order kinetics according to the geometrical factor. The energy activation values obtained using different kinds of measurements are in good agreement, including the Kitis method for deconvolution of the glow curve. Furthermore, the results agree with those presented by other authors.

Dosimetric properties of KMgF3:Tb + PTFE

This work presents the results obtained from the dosimetric properties of the new radiation detectors of KMgF3:Tb + PTFE. The thermoluminescent material was obtained by microwave technique. The polycrystalline powder obtained was mixed with polytetrafluoroethylene resin powder in the ratio 2:3 to make dosimeters in pellet form. The thermoluminescent response of these new detectors presented a linear behavior, in the dose range between 1 and 1000 Gy 60Co gamma radiation, the repeatability test in the measurements, during ten cycles of heat treatment, irradiation and readouts, showed ± 3.7% DS, the stability test of thermoluminescent signal, during two months showed that the fading is practically null. For the results obtained, this new detector could be very useful for radiation dosimetry, in clinical applications.

Study of Heating Rate Effect on Thermoluminescence Glow Curves of LiF: Mg, Cu, P

The samples of LiF: Mg,Cu,P powder (xeri: GR-200) were irradiated by the gamma radiation resource with varied exposed dose. The glow curves of thermoluminescence (TL) material were observed with the defferent heating rates. The influence of heating rate on the thermoluminescence property of LiF: Mg,Cu,P was analyzed. The results showed that as the heating rate increases, the peak intensity at the maximum decreases and shifts to higher temperature. The thermoluminesecnce sensitivity of the material also changes and has the optimal value at 6oC/s. This value is also adaptable for measurement of natural environmental and archaeologicaldose.

Thermoluminescence glow curve deconvolution and trapping parameters determination of dysprosium doped magnesium borate glass

In this paper, thermoluminescence glow curves of gamma irradiated magnesium borate glass doped with dysprosium were studied. The number of interfering peaks and in turn the number of electron trap levels are determined using the Repeated Initial Rise (RIR) method. At different heating rates (β), the glow curves were deconvoluted into two interfering peaks based on the results of RIR method. Kinetic parameters such as trap depth, kinetic order (b) and frequency factor (s) for each electron trap level is determined using the Peak Shape (PS) method. The obtained results indicated that, the magnesium borate glass doped with dysprosium has two electron trap levels with the average depth energies of 0.63 and 0.79 eV respectively. These two traps have second order kinetic and are formed at low temperature region. The obtained results due to the glow curve analysis could be used to explain some observed properties such as, high thermal fading and light sensitivity for such thermoluminescence material. In this work, systematic procedures to determine the kinetic parameters of any thermoluminescence material are successfully introduced.

Synthesis and dosimetry features of novel sensitive thermoluminescent phosphor of LiF doped with Mg and Dy impurities

Lithium fluoride doped with Mg and Dy was fabricated for the first time using melting method. The optimum concentrations of impurities and thermal treatment were studied to achieve high thermoluminescence (TL) sensitivity. TL sensitivity of the fabricated phosphor is close to that of TLD-100 powder. Tm-Tstop technique was used to identify the number of overlapped TL glow peaks. Initial rise, isothermal decay and computerized glow curve deconvolution (CGCD) methods were applied to obtain kinetic parameters of the prepared TL material. Three component glow peaks were distinguished at temperatures 395, 448 and 510 K. Other TL properties such as fading, linearity of dose response and reusability are also presented and discussed.