Thermoluminescent Materials Research Articles

Investigation on various types of silica fibre as thermoluminescent sensors for ultra-high dose radiation dosimetry

With high-dose applications lacking the benefit of an economic yet versatile dosimeter that provides for a wide dynamic dose range, ongoing research is seeking to introduce suitable thermoluminescent (TL) material for such needs. Acknowledging the high potential of silica fibres, as developed by members of this group over the past few years, in present work evaluation has been made of 13 types of fibre, differing in dopant, dopant concentration and diameter including P−, Al−, Er−, Ge− and Al-Tm-doped fibres, ultra-high numerical aperture and borosilicate fibre, and two non-doped fibres, quartz and suprasil F300. Evaluation is made in terms of TL response to photon and electron irradiations with the objective of determining a TL material that can offer sensitive yet extended dose capability, saturating only above the few tens of kGy range. The various silica fibres that have been investigated were found to show saturation levels from 5 kGy for Ge-doped fibre (4 mol %) to 80 kGy for 2 mol % Al−doped silica fibre. Borosilicate fibres demonstrated the greatest potential for high dose dosimetry, maintaining a highly-linear response, any tendency towards saturation only being indicated to beyond receipt of doses of 100 kGy. For this fibre type detailed TL characterizations were conducted, including glow curve analysis, reproducibility and fading tests. The results suggest borosilicate fibre to be suitable for high dose TL dosimetry, providing sufficient sensitivity and appropriate dosimetric characteristics.

Tuff Rock as a New Thermoluminescent Material for Gamma Dosimetry

Tuff Rock as a New Thermoluminescent Material for Gamma Dosimetry

Effect of Si codoping on thermoluminescence properties of undoped and RE (RE:Ce/Tb/Pr/Eu/Yb/Nd) doped YAG phosphor under UV, and γ-ray irradiation

The objective of this work is to test an efficient material synthesis method, for the development of thermoluminescence (TL) material using yttrium aluminium garnet. The TL properties of undoped, Ce/Tb/Pr/Eu/Yb/Nd doped Y3Al5O12 (YAG) polycrystalline material, synthesized by combustion synthesis at low temperature, under ultra-violet (uv) and γ -rays irradiation is reported. The effect of controlled Si codoping is also inspected. The introduction of the doping ions induces changes in the trapping processes and the TL efficiency. The TL signal of Ce doped YAG samples indicates a high sensitivity to uv, γ-ray irradiation. It has been found that there is a prominent enhancement in TL glow peak with Si doping. Trapping parameters of uv irradiated YAG:Ce/Si were calculated from the TL data. The prepared ceramics have found potential application for uv and γ−ray radiation dosimetry purpose.

Evaluation of the thermoluminescence kinetic parameters of zinc‐borosilicate glass after gamma‐irradiation

AbstractUp until this moment, there was no detailed study concerning the kinetic parameters of zinc‐doped borosilicate glass thermoluminescent (TL) material. A significant TL peak was observed upon gamma irradiating the samples, at around 185°C. Evaluating activation energy (E), frequency factor (s), and order of kinetics (b) were conventionally obtained by peak shape (PS) method, repeated initial rise (RIR), and variable heating rate (VHR) methods. The obtained results indicated that the zinc‐doped borosilicate glass glow curve after gamma irradiation is legitimately a superposition of seven interfered glow peaks. Therefore, we cannot use computerized glow curve deconvolution (CGCD) method alone in determining the kinetic parameters in this case. Additive dose (AD), repeated initial raise (RIR), and variable heating rate (VHR) methods together with computerized deconvolution (CGCD) method by using the TolAnal software have been applied to determine the kinetic parameters of zinc‐borosilicate glass due to the existence of several nearby overlapped peaks. RIR method gives the value of ± 2.3% average variation, for the activation energies, compared with those obtained by GCDC. The obtained results clearly show the consequences reliability.

The effect of different dopant concentration of tailor-made silica fibers in radiotherapy dosimetry

In thermoluminescence (TL) material dopant concentration has an important effect on their characteristics as a “radiation-sensor”. The study investigates dosimetric properties of four different concentration (4mol%, 5mol%, 7mol% and 25mol%) tailor-made Ge-doped silica fibers. The intention is to seek development of alternative TL materials that offer exceptional advantages over existing passive systems of dosimetry, including improved spatial resolution, a water impervious nature and low cost. Photon beams (6MV and 10MV) from a clinical linear accelerator were used for irradiation of the fiber samples over radiation therapy doses, ranging from 0.5Gy to 8Gy. SEM-EDX analysis was also performed to investigate the homogeneity of distribution of Ge dopant concentration from the fiber samples. The results of measurement were also compared with two of the more commonly used standard TLDs, TLD-100 (LiF: Mg,Ti-7.5% 6LiF) and TLD-700 ((7LiF: Mg,Ti-99.9%7LiF) chips respectively. The TL intensity of the fiber samples was found to strongly depend on Ge dopant concentration, with samples showing enhanced TL yields with decreasing Ge dopant concentration. 4mol% Ge-doped silica fiber provided the greatest response whereas the 25mol% samples showed the least, indicative of the well-known concentration quenching effects All fiber TLDs provided linear dose response over the delivered radiotherapy dose-range, the fibers also showing a weak dependence on photon beam energies in comparing the TL yields at 6 and 10MV. The fading behavior of the different concentration Ge doped TLD-materials were also measured over a period of thirty (30) days subsequent to irradiation. The relative sensitivity of the samples with respect to standard TLD-100 were found to be 0.37, 0.26, 0.13 and 0.02 in respect of the 4, 5, 7 and 25mol% fibers. The primary dosimetry peak, which was by far the most prominent of any other feature covered by the glow curve, was found to be around 244°C using the most sensitive silica fiber. The study is expected to pave the way in making more comprehensive investigations aimed at defining improved TL response fiber samples.

Investigation of Optically Stimulated Luminescence and Signal Fading Properties of Several Materials.

Optically stimulated luminescence (OSL) dosimetry involves the illumination of an irradiated sample on an appropriate material to produce a stimulated emission of light, whose intensity is indicative of the radiation dose. This technique is currently used for personnel dosimetry, environmental dosimetry, and geological dating applications. While a great deal of published research focusing on α-Al2O3:C and natural materials used for geological dating exist, relatively little is known about the OSL properties of thermoluminescent (TL) materials. This paper reports the results of an experiment conducted to characterize the OSL behavior of KBr, CaSO4:Tm, CaSO4:Dy, CaSO4:Dy+P, LiF:Mg,Cu,Na,Si, and LiF:Mg,Cu,Si. The OSL signal responses to seven excitation wavelengths from 625 nm to 455 nm for each material were measured at 12 time periods post-irradiation from 6 h to 120 d. The magnitude and fading characteristics of the OSL response of each material were then analyzed. The data demonstrated that significant OSL responses exist for CaSO4:Tm, LiF:Mg,Cu,Na,Si, and LiF:Mg,Cu,Si. In addition, it was found that the fading rates of OSL signals depend on the excitation wavelength used to elicit the signals and that these fading rates and the corresponding excitation wavelengths correlate well with the material's TL behavior. Thus, the various fading rates with respect to the excitation wavelengths could be used to obtain temporal dose information.

PO-0764: A study of Tandem systems incorporating three thermoluminescent dosimetry materials

PO-0764: A study of Tandem systems incorporating three thermoluminescent dosimetry materials

New algorithm for analyzing phosphorescence curves: Its application to the K2YF5:Pr compound

Analysis of phosphorescence curves is an alternative procedure to glow curve analysis in order to find the parameters characterizing trap and recombination centers of thermoluminescence materials. In this article a new algorithm to analyze phosphorescence curves is reported, which is derived from the set of coupled differential equation describing the carrier traffic without resorting to approximations. The new algorithm has been employed to analyze the phosphorescence curves of the K2YF5:Pr compound.

Modified Pechini's method to prepare LaAlO3:RE thermoluminescent materials

This work presents an alternative method to prepare rare-earth doped lanthanum aluminates materials for thermoluminescent (TL) dosimetry applications. Modified Pechini´s method was using to prepare praseodymium doped LaAlO3 powders. LaAlO3:Pr3+ powders were prepared using La(NO3)3·6H2O, Al(NO3)3·6H2O, Pr(NO3)3·6H2O, citric acid, and ethylene glycol. The solution was heated to 80°C for its polyesterification reaction. The obtained powders were submitted at different thermal treatment from 700 up to 1600°C. The structural and morphological characterizations were carried out using X-ray diffraction (XRD) and scanning electron microscopy techniques. TL glow curves of the X-ray irradiated samples showed one peak for europium and praseodymium dopants, meanwhile for powders doped with dysprosium ion showed two peaks. The technique is low cost, faster and it produces homogeneous particles can be used as thermoluminescent phosphors.

Activation Energy of Modified Peak Shape Equations

The aim of this paper is to give some simplified expressions related to the peak shape method. The modified equations have been used to calculate the activation energy (E) of commercial thermoluminescent dosimeters (TLD), as well as of ZnO thermoluminescent material produced in laboratory; the values so determined have been compared to the values obtained using the classical expressions of the peak shape method. The modified equations proposed are as a function of peak shape parameters or the peak temperature at the maximum. This expression could be useful to obtain approximated E values in the case of complex glow curves as well, when the peaks are not well resolved but the peak temperature at the maximum may be easily determined.

Thermoluminescence and optically stimulated luminescence properties of Dy3+-doped CaO–Al2O3–B2O3-based glasses

We developed Dy3+-doped CaO–Al2O3–B2O3 based glasses with Dy concentrations of 0.5, 1.0, and 2.0mol% using a melt-quenching technique. The as-synthesized glasses were applicable as materials exhibiting thermoluminescence (TL) and optically stimulated luminescence (OSL). The optical and radiation response properties of the glasses were characterized. In the photoluminescence (PL) spectra, two emission bands due to the 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions of Dy3+ were observed at 480 and 580nm. In the OSL spectra, the emission band due to the 4F9/2→6H15/2 transition of Dy3+ was observed. Excellent TL and OSL responses were observed for dose ranges of 0.1–90Gy. In addition, TL fading behavior was better than that of OSL in term of the long-time storage. These results indicate that the Dy3+-doped CaO–Al2O3–B2O3-based glasses are applicable as TL materials.

Thermoluminescent microparticle thermal history sensors.

While there are innumerable devices that measure temperature, the nonvolatile measurement of thermal history is far more difficult, particularly for sensors embedded in extreme environments such as fires and explosions. In this review, an extensive analysis is given of one such technology: thermoluminescent microparticles. These are transparent dielectrics with a large distribution of trap states that can store charge carriers over very long periods of time. In their simplest form, the population of these traps is dictated by an Arrhenius expression, which is highly dependent on temperature. A particle with filled traps that is exposed to high temperatures over a short period of time will preferentially lose carriers in shallow traps. This depopulation leaves a signature on the particle luminescence, which can be used to determine the temperature and time of the thermal event. Particles are prepared—many months in advance of a test, if desired—by exposure to deep ultraviolet, X-ray, beta, or gamma radiation, which fills the traps with charge carriers. Luminescence can be extracted from one or more particles regardless of whether or not they are embedded in debris or other inert materials. Testing and analysis of the method is demonstrated using laboratory experiments with microheaters and high energy explosives in the field. It is shown that the thermoluminescent materials LiF:Mg,Ti, MgB4O7:Dy,Li, and CaSO4:Ce,Tb, among others, provide accurate measurements of temperature in the 200 to 500 °C range in a variety of high-explosive environments.

Preparation of new thermoluminescent material (100−x)B2O3–xLi2O: Cu2+ for sensing and detection of radiation

The copper-doped lithium borate glass as a thermoluminescent (TL) material (100−x) B2O3–xLi2O : Cu2+ (x= 20, 50 and 80 mol%) was prepared by the combustion method. The formation of (100 −x)B2O3–xLi2O : Cu2+ after doping 2, 3 and 5 ppm Cu2+, was characterized by Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The TL characteristics of the synthesized material were studied at different parameters. The synthesized glass 50B2O3–50i2O : Cu2+ with 3 ppm of doped Cu2+, exhibited the superior TL properties than other glasses prepared in the current study. The spin-Hamiltonian parameters were assessed using the electron spin resonance spectra of 50B2O3–50Li2O : Cu2+ doped with 3 ppm Cu2+. The spin-Hamiltonian parameter values in the case of Cu2+ revealed that the ground state of Cu2+ was dx 2–y 2 orbital (\(^{\mathbf {2}}\text {B}_{\mathbf {1g}}\)) and the site symmetry around Cu2+ ion was distorted octahedral. TL glow curves were recorded with different heating rates (1, 2, 5, 10, 15, and 20∘C s−1) at the fixed dose 10 × 103 Gy. The results revealed that the glow peak position shifted to higher temperature with heating rate and the heating rate of 10∘C s−1 showed the superior TL response with highest glow peak which is very good for dosimetry purposes.

Thermoluminescence Response of Germanium-Doped Silica (SiO<sub>2</sub>) Optical Fibers Subjected to X-Ray Irradiation

We have investigated the suitability of 8% mole of tailor-made germanium (Ge)- doped silica (Si02) cylindrical fibers to use as the detector, to map dose that received by the patient during the treatment especially for X-ray radiation. The diameters of these cylindrical optical fibers are; 362μm, 483μm and 604μm with different in masses and have been supplied by Telekom Malaysia (TM) group. To study the thermoluminescence reponse of these fibers, X-ray source with 60 kVp, 80 kVp and 100 kVp were used to irradiate the samples. The dosage of X-ray source was measured by the calibrated ionization chamber. The potential of these (Ge) - doped silica (Si02) cylindrical fibers as an efficient thermoluminescence (TL) material was investigated comparing the thermoluminescence response of the fibers with standard TLD 100. In confronting the variation of the dopant concentration (Germanium) along the core of the optical fibers, the individual calibrations so called as Elemental Correction Coefficient (ECC) were carried out. The results showed that, the best annealing temperature and time (to erase the previous signal) for the samples are 400 °C for one hour. The TL Yield (measured in counts per second per unit mass of fiber) increases as the dose of X-ray beams increases from 0.08 Gy up until 2.8 Gy. The results were clearly indicated that the TL response of SiO2 fibers were energy dependent. It can be concluded that, Ge-doped optical Silica (SiO2) optical fibers is very suitable to use as TLD to measure dose in medical applications.

Effective atomic numbers for photon energy absorption and energy dependence of some thermoluminescent dosimetric materials

Effective atomic number for photon energy absorption (Z peaeff ), the relative effective atomic number of the thermoluminescent dosimetric (TLD) materials with respect to air (Z reff ), and energy dependence (ED) of the TLD materials such as beryllium oxide (BeO), lithium tetraborate (Li 2 B 4 O 7 : Cu, Ag, P), aluminum oxide (Al 2 O 3 ), calcium fluoride (CaF 2 ), and titanium oxide (TiO 2 ) in the energy range of 1 keV to 20 MeV have been studied. The values of ZPEA eff and ZR eff show a broad peak and a maximum value around 20 keV for BeO, around 60 keV for CaF2 and TiO 2 , and around 40 keV for Al 2 O3 and Li 2 B 4 O 7 : Cu, Ag, P. Overall, the effective atomic number (Z eff ) varies linearly with ED for all the materials in the photon energy range of 1 keV to 20 MeV except TiO2 and thereby confirming the validity of a more commonly employed method of using the Z eff to calculate the measure of the ED in TLD. The ED values show a broad peak around 30 keV for CaF 2 and TiO 2 and around 20 keV for Al 2 O 3 and remain almost constant for the other two materials.

Thermoluminescent dosimetric properties of CaF2:Tm produced by combustion synthesis

Abstract Calcium Fluoride is one of the oldest known thermoluminescent materials and is considered to be one of the most sensitive. This work presents the dosimetric properties results of CaF2:Tm produced by combustion synthesis. The X-ray diffraction confirmed that CaF2 was successfully produced. TL emission spectra, obtained using a Hammamatsu optical spectrometer, have the same lines of commercial CaF2:Tm, although transitions 3P0→3F4 (455 nm) and 1G4→3H6 (482 nm) are shown to be proportionally more intense. The deconvolution technique was employed and seven glow peaks were found similar to the commercial CaF2:Tm. A linear dose response curve was obtained for the range 0.1 mGy to 100 Gy, with the onset of a supralinear behavior at 50 Gy up to 100 Gy. The minimum measurable dose for gamma was around 100 μGy for a 6.0 mm diameter by 1.0 mm in thickness pellet. No significant fading was observed in 60 days of storage, within experimental uncertainties, showing that the main dosimetric peak is stable.

Present status and future trends in the development of thermoluminescent materials

There is a continuous growing interest in developing materials for TL radiation dosimetry, especially in the fields of medical, environmental and personal applications. Although several phosphors are being used in these fields today, many efforts are being made in order to develop new TL materials, having better tissue equivalence, and increased sensitivity to gamma radiation, high energy photons, electrons, neutrons and heavy ions. Different preparation methods and properties of several TL materials have been studied so far and it is found that many of these materials constitute a class of TL phosphors with good performances, especially when they are doped with suitable activators.Most widely used and extensively studied materials for TL dosimetry (TLD) are fluorides, sulfates, borates and sulfides of alkali and alkaline earth elements. Besides these, have been developed other phosphors based on metal oxides and mixtures of metal oxides, halo sulfates and different kinds of glasses and perovskites. In this paper, a review of the status and future trends in the development of TL materials is presented.

Análise termoluminescente de compósitos de CaSO4 ativado com terras raras

Desde que a termoluminescência começou a ser aplicada à dosimetria das radiações ionizantes em 1940, diferentes materiais detectores têm sido propostos, sendo o CaSO4um dos mais usuais. A motivação deste trabalho foi produzir cristais de CaSO4dopados com elementos terras raras como o európio (Eu), o neodímio (Nd) e o túlio (Tm). Também foram produzidos cristais de CaSO4:Ag. O interesse na produção desses materiais foi o de investigar outras metodologias de produção de materiais termoluminescentes. Os resultados obtidos mostram que o CaSO4:Tm apresenta maior potencial para ser utilizado na dosimetria termoluminescente, pois, embora não sendo o mais intenso, o pico TL em 170°C pode servir como pico dosimétrico. Análises de linearidade mostraram que as respostas TL foram proporcionais às dosesabsorvidas.

THERMOLUMINESCENCE RESPONSE OF NANOPARTICLES GOLD DOPED LITHIUM BORATE GLASS SUBJECTED TO PHOTON IRRADIATION

The absorption coefficient of Borates glass is much closed to human body tissue. This fact makes borates as an ideal material for thermoluminescence material either for medical or environmental application. In this study, a glass system of 15% Li2CO3+ 85% H3BO3 doped with 0.1mol %nano-gold was prepared by using melt-quenching technique. Undoped and Au doped lithium borate glass samples were exposed to Co-60 gamma ray (1.25 MeV) with various doses ranging from 10 to 60 Gy by using Gammacell 220 excel. Various TL properties such as TL glow curve, linearity and sensitivity of the prepared glass were investigated. From the TL glow curve, it was found that the TL intensity increased by addition of Au into the glass system. The TL intensity of Au doped glass increases about 23 times higher than the undoped glass. The study also shows that the doped borate glass has a linear response subjected to Co-60 gamma irradiation at doses ranging from 10 to 60 Gy. The sensitivity of doped glass is about 22 times higher compared to un-doped glass

Thermoluminescence of LiF:Mg,Ti (TLD 100) Subject to 1.25 Mega Electron Volt Gamma Radiotherapy

Attempt has been made to investigate the thermoluminescence (TL) of LiF:Mg,Ti (TLD 100) chip irradiated with gamma energies of 1.25 MeV. The TL response increases over a wide photon dose range, from 1.0 to 10 Gy. The LiF:Mg,Ti demonstrates useful TL properties and represents as an excellent candidate for use in TL dosimetry of ionizing radiation. TLD 100 dosimeter has been found to yield a linear dose-TL signal relationship. Its linearity and sensitivity have been observed. The TL high sensitivity of TLD 100 makes it a very promising TL material for use in research and a variety of other applications.