Thermoluminescence Sensitivity 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.

Thermoluminescence dosimetry and microstructural characteristics of gamma-irradiated natural flake graphite

Thermoluminescence (TL) and microstructural analysis were conducted on natural flake graphite (NFG) to assess its suitability for radiotherapeutic x-ray dose measurements. The investigations encompassed the examination of TL glow curves, linearity, sensitivity, signal decay, and repeatability. NFG samples were exposed to 60Co gamma radiation doses ranging from 2 Gy to 20 Gy. The microstructure of the irradiated NFG was probed using a 532 nm laser Raman spectrometer. Promisingly, the NFG exhibited remarkable characteristics, including a moderately higher response to dose (R2 of about 96%), increased sensitivity at lower doses, and good repeatability (∼4%). Nevertheless, its fading rate reached about 80% after 14 days of irradiation. Additionally, the NFG intensity ratios of defect (D) to graphite (G), denoted as ID/IG, closely mirrored the oscillatory pattern observed in 50 μm thick graphite sheets and were approximately 1.6 times lower than those of similar graphite sheets with comparable carbon content (about 98% carbon). These findings suggest that NFG holds potential for the development of an affordable, non-hygroscopic, and tissue-equivalent TL dosimeter, with possible applications in the medical field.

Investigation of structural, photo and thermoluminescence properties of YAGG:Ce nanogarnet for medical dosimetry application

Cerium-doped yttrium aluminum gallium garnet (YAGG:Ce3+) nanophosphors were synthesized using the sol-gel method. Mixed garnet of Y2.97Al5-xGaxO12:Ce0.03 was prepared with varying gallium content: x = 0, 1, 2 and 3 Ga. The effect of gallium substitutions on the structural, photo and thermoluminescence properties of the prepared nanophosphors were studied by X-ray diffraction (XRD), photoluminescence (PL) and thermoluminescence (TL) techniques. XRD results indicated that the single and pure cubic crystal phase was formed for all nanophosphor samples regardless of the Ga content. The PL spectra of all the samples exhibited a green-yellow emission band centered at 522 nm attributed to the 5d → 4f transitions of Ce3+ ions. The TL glow curve spectra recorded after β-particle irradiation showed a strong dependence in terms of position, shape and intensity, of all temperature peaks with the Ga content. The highest TL sensitivity was observed for the sample prepared with x = 2 Ga, with main peak arising at low temperature (85 °C). The sample prepared at x = 1 Ga exhibited also high TL sensitivity with a simple glow curve spectrum showing a main peak at high temperature (∼158 °C). Thus, the linear dose response of this sample has been investigated in the wide dose range from 0.125 to 100 Gy in order to evaluate the potentiality of this material for radiation dosimetry applications.

Dosimetric properties of Cr–La, Cr–Cu, and Cu–La ions codoped Ca9 Al (PO4)7 nanostructure

In the present work, Cr–La, Cr–Cu, and Cu–La ions codoped Ca9Al (PO4)7 nanostructures (symbolized as Cr–La, Cr–Cu, and Cu–La) were prepared using the sol-gel method for their dosimetric properties. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results reflected the existence of the nanoparticle structure. This confirmed the successful sol-gel preparation method used. The surface morphological properties of the prepared samples were scrutinized by scanning electron microscopy (SEM). The presence and distribution of the constituent elements of the samples were determined using energy-dispersive X-ray (EDX) spectroscopy. The thermoluminescence (TL) sensitivity enhancement and homogenous properties of the prepared samples were assessed using a γ-radiation dose of 5 Gy. TL sensitivity of the Cr–Cu sample was found to be optimum. The relative standard deviations (RSD) of the homogenous study were found to be 6.5, 5.7, and 3.9% for Cr–La, Cr–Cu, and Cu–La, respectively, which were acceptable according to the ISO requirements (<10%). The dose-linearity response was investigated in 0.5 up to 20 Gy γ-dose ranges. The sample Cr–Cu had a good dose-linearity of up to 20 Gy while the others (Cr–La and Cu–La samples) had a dose-linearity of up to 13 Gy. The threshold doses (MDD) of the Cr–La, Cr–Cu, and Cu–La samples were computed and found to be approximately 110, 32, and 134 μGy, respectively. The photon attenuation parameters of the prepared samples were computed using the Phy-X PSD program, and the acquired data showed that the Ca9Al (PO4)7 composition had bone-equivalent material characteristics. Results of the dosimetric properties of Cr–La, Cr–Cu, and Cu–La co-doped Ca9Al (PO4)7 samples suggested that these compositions had potentially excellent TL characteristics to be used in various dosimetric applications across a broad range of gamma doses.

Thermoluminescence (TL) and electron paramagnetic resonance (EPR) of dumortierite sensitized by heat treatments

The present study presents the effect of heat treatment on TL and EPR of dumortierite. It was found that applying a heat treatment at 1200 °C for 1h, followed by slow cooling to room temperature, is optimal for improving its TL sensitivity. The glow curves of the sensitized dumortierite sample show TL emission bands centered at 350, 475, and 580 nm. The kinetic parameters of the TL peaks were obtained using the Tm-Tstop and deconvolution methods. In addition, sensitized dumortierite exhibits a linear response with γ-radiation dose and low fading in its TL response. Studies using the technique of EPR were carried out to investigate the defect center EPR signals observed after γ-irradiation. A single defect center with an axially symmetric g-tensor was observed with principal values g∥ = 2.0009 and g⊥ = 2.0017. The center was attributed to an F+ center and appears to correlate with the TL peak at 200 °C.

Synthesis and characterization of high-sensitivity Dy,Eu co-doped CaSO4 thermoluminescent phosphor using coprecipitation technique.

In this work, (99 - x)CaSO4 -Dy2 O3 -xEu2 O3 , (where x = 0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) thermoluminescence phosphors were prepared using a coprecipitation method. The thermoluminescence (TL) dosimetry (TLD) characteristics such as TL sensitivity, dose-response, minimum detectable dose, thermal fading, and the effect of sunlight on the prepared phosphors were investigated. The obtained results indicated that the most sensitive phosphor was obtained at x = 0.05. Large thermal fading of 6% after 1 h and 26% after 24 h from irradiation followed by 71% after 1 month with no additional fading was observed within a time frame exceeding 2 months throughout the remaining duration of the investigation, which also spanned over 2 months. Despite the phosphor's high fading rate, the relative sensitivity of the prepared samples was ~90% compared with TLD-100. The marked effect of day sunlight was also determined. High dose-response within the low-dose range from 0.01 to 5 Gy was observed. The obtained results suggested that the synthesized phosphor is well suited for applications involving radiation biology and radiotherapy dosimetry.

Effect of route production and doping concentration on luminescence response of MgB4O7: Gd phosphor

This work studied the synthesis route and gadolinium (Gd) doping concentration on magnesium tetraborate (MBO) luminescence response. The material was synthesized by solid-state reaction techniques with two different procedures (Routes A and B) for three different Gd concentrations (0.2, 0.3, and 0.7 %wt). Route A consisted of the synthesis of the MBO matrix and subsequently add Gd2O3 as an activator. Route B the material was obtained after mixing and co-milling the precursors and the activator together prior to synthesis. Rietveld refinement of experimental X-ray diffraction data indicates that the MgB4O7:Gd compounds exhibit single phases consistent with orthorhombic symmetry (space group Pbca (61)). These compounds also evidenced contributions Gd dopant concentrations in MgB4O7 matching the cubic symmetry of the material. The electron microscopic scan surface morphological study exhibited the formation of polycrystalline material with diverse grain shapes for the two production routes. Compositional characterization by electron X-ray energy spectroscopy suggested that there were no other elements besides the expected elements in the material. The optical response by diffuse reflectance spectroscopy estimated the energy gap from the fundamental absorption of the undoped host. Optically stimulated luminescence response suggested that MgB4O7:Gd 0.7%wt (route B) sensitivity is 2.1 times higher than that presented in MgB4O7:Gd 0.3 % (route A). Thermoluminescence experiments showed that the optimum Gd dopant concentrations for the most intense dosimetric peak of phosphorus MgB4O7 fabricated using routes A and B were 0.3 % (main peak: 209 °C) and 0.7 % (main peak: 276 °C), respectively. The thermoluminescence sensitivity of MgB4O7:Gd 0.3%wt (route A) is 3.5 times higher than the sensitivity of MgB4O7:Gd 0.7%wt (route B).

Synthesis, characterization and thermoluminescence properties of LiCaPO4 phosphor for ionizing radiation dosimetry

Many minerals and compounds show thermoluminescence (TL) properties but only a few of them can meet the requirements of an ideal dosimeter. Several phosphate materials have been studied for low-dose dosimetryin recent times. Among the various phosphates, ABPO4-type material shows interesting TL properties. In this study, an ABPO4-type (A = Lithium, B=Calcium) phosphor is synthesized using a modified solid-state diffusion method. Temperature is maintained below 800 °C in every step of phosphor preparation to obtain the pure phase of Lithium calcium phosphate (LiCaPO4). The purpose of this work is to synthesize LiCaPO4 using a simple method, examine its structural and luminescence properties in order to gain a deeper understanding of its TL characteristics. The general TL properties, such as TL glow curve, dose linearity, sensitivity, and fading, are investigated. Additionally, this study aims to determine various kinetic parameters through Glow Curve Deconvolution (GCD) method using the Origin Lab software together with the Chen model. XRD analysis confirmed the phase purity of the phosphor with a rhombohedral structure. Lattice parameters, unit cell volume, grain size, dislocated density, and microstrain were also calculated from XRD data. Raman analysis and Fourier Transform Infrared analysis were used to collect information about molecular bonds, vibrations, identity, and structure of the phosphor. To investigate TL properties and associated kinetic parameters, the phosphor was irradiated with 6.0 MV (photon energy) and 6.0 MeV (electron energy) from a linear accelerator for doses ranging from 0.5 Gy to 6.0 Gy. For both photon and electron energy, TL glow curves have two identical peaks near 200 °C and 240 °C.The TL glow curves for 0.5 Gy–6 Gy are deconvoluted, then fitted with the appropriate model and then calculated the kinetic parameters. Kinetic parameters such as geometric factor (μg), order of kinetics, activation energy (E), and frequency factor (s) are obtained from Chen's peak shape method. The dose against the TL intensity curve shows that the response is almost linear in the investigated dose range. For photon and electron energy, the phosphor is found to be the most sensitive at 2.0 Gy and 4.0 Gy, respectively. The phosphor shows a low fading and after 28 days of exposure, it shows a signal loss of better than 3%. The studied TL properties suggest the suitability of LiCaPO4 in radiation dosimetry and associated fields.

Thermoluminescence studies of NaMgF3:Tb for gamma dosimetry applications

NaMgF3 is a recognized sensitive thermoluminescence (TL) dosimeter but it shows fading at room temperature which limits its use as a radiation dosimeter. It is important to improve this parameter of NaMgF3 for its potential application in the field of radiation dosimetry. Thus, the current work focuses on enhancing the dosimetric properties of NaMgF3 exclusively the TL fading characteristics. In the present study, Tb doped NaMgF3 has been synthesized by two different methods i.e. solid state reaction method (SSR) and melting method (MT). A comparative and detailed TL studies have been carried out after irradiation with gamma rays which has not been reported so far. Detailed analysis of TL and Photoluminescence (PL) properties reveal that NaMgF3:Tb prepared via MT shows good luminescence properties in comparison to SSR and previously reported results. Thus, Tb doped NaMgF3 synthesized by melting method can be a potential dosimeter for the detection of gamma rays.

Study on the thermoluminescence and optically stimulated luminescence of LiMgPO4:Dy phosphors synthesized by different methods

LiMgPO4:Dy phosphors were synthesized by high-temperature solid-state method and sol-gel method. The effects of different synthesis methods on crystal structure, morphology, thermoluminescence (TL) properties, and optically stimulated luminescence (OSL) properties of LiMgPO4:Dy were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), TL glow curve and continuous wave OSL (CW-OSL) curves. XRD patterns showed that the crystal phase of the samples synthesized by the two methods is LiMgPO4. The morphology of the samples synthesized by sol-gel method was better than that synthesized by high-temperature solid-state method. The TL sensitivity of the samples synthesized by sol-gel method was higher than that synthesized by high-temperature solid-state method. The TL strongest glow peak of the LiMgPO4:Dy sample synthesized by high-temperature solid-state method was 363 K, while that the LiMgPO4:Dy sample synthesized by sol-gel method was 380 K. The OSL sensitivity of the samples synthesized by sol-gel method was significantly higher than that synthesized by high-temperature solid-state method. The synthesis method had no effect on the OSL decay of the sample. LiMgPO4:Dy phosphor synthesized by sol-gel method may be a suitable candidate material for radiation dosimetry.

Beta particle excited thermoluminescence of new ZnO:Ce phosphors

This work reports on the beta particle excited thermoluminescence (TL) of ZnO:Ce phosphors, synthesized through a controlled chemical precipitation reaction followed by thermal annealing at 900 °C in an air atmosphere during 24 h. The successful obtention of crystalline hexagonal zincite structure was confirmed by X-Ray diffraction. By milling ZnO:Ce powder precipitated during the reaction before carrying out the thermal annealing, there are improved reproducibility and enhanced TL features of interest for dosimetry. Ce doping strongly increases the TL sensitivity and leads to a simpler glow curve shape. The TL – dose response exhibits a linear behavior at least up to 128 Gy. The sensitivity of the synthesized ZnO:Ce is ca. 103 times greater than that of undoped ZnO. The TL fades 22% two days after radiation exposure, and then it becomes negligible.

Investigation of dosimetric properties of CaSO4:Mn phosphor prepared using slow evaporation route

The objective of this work was to investigate the luminescent properties of CaSO4:Mn synthesized by slow evaporation route. The crystalline structure, morphology, thermal and optical properties of the phosphors were characterized by X-ray diffraction analysis (XRD), Scanning electron microscopy (SEM), photoluminescence (PL) and thermogravimetric analysis (TGA). Moreover, using thermoluminescence (TL) and optically stimulated luminescence (OSL) techniques, the dosimetric properties of the phosphors, such as emission spectra, glow curve reproducibility, dose-response linearity, fading of the luminescent signal, variation of the TL intensity with the heating rate, OSL decay curves, correlation between TL and OSL emissions and minimum detectable dose (MDD) were comprehensively investigated. For dosimetric analyses, the samples were irradiated with doses from 169 mGy to 10 Gy. The emission band fits with the characteristic line of the Mn2+ emission features, ascribed to 6A1→4T1 transition. CaSO4:Mn pellets present a TL glow curve with a single typical peak centered around 494 nm, an OSL decay curve with predominance of a fast decay component, and a MDD on the order of mGy. The luminescent signals showed to be linear and reproducible in the studied dose range. The trapping centers located between 0.83 eV and 1.07 eV were revealed for different heating rates in the TL study. The high TL sensitivity of CaSO4:Mn was proven when comparing with commercially available dosimeters. The luminescent signals exhibit a smaller fading than described in the literature for CaSO4:Mn produced by other methods.

Thermoluminescence investigations and kinetic analysis of highly sensitive LiCaAlF6: Eu,Y phosphor for dosimetric applications

The paper presents detailed thermoluminescence characterization and kinetic analysis of highly sensitive and dosimetric grade lithium calcium aluminum fluoride doped with europium and co-doped with yttrium (LiCaAlF6:Eu,Y). It is synthesized by melt processing technique. The thermoluminescence (TL) and optically stimulated luminescence (OSL) correlation was systematically studied. The study reveals that the OSL signal is attributed to the observed TL peaks in this material. Thus, same defects are responsible for TL and OSL in LiCaAlF6:Eu,Y. Further characterization involved measurement of TL emission spectrum, OSL emission spectrum, steady state photoluminescence (PL) spectra, phosphorescence, sensitivity, fading, dose response etc. The TL sensitivity of this phosphor was observed to be ∼5 times and ∼3 times to that of CaSO4:Dy and commercially available Al2O3:C respectively. PL, TL and OSL emission spectra suggest that Eu2+ ion acts as a luminescence center in this material. Minimum measureable dose for the phosphor in TL mode was found to be 0.3 μGy with negligible fading post 10 days of irradiation. The fading of TL signal in this material is similar to the one observed for OSL signal. The thermal stability and hygroscopic nature of LiCaAlF6:Eu, Y were studied using thermogravimetric and differential scanning calorimetry techniques. Owing to the attributes like high sensitivity, wide dynamic dose range it stands as a viable and excellent phosphor material for various radiological and 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.

New perspectives on traps and radiative recombination centers for optically stimulated luminescence in LiF:Mg,Cu,P

LiF:Mg,Cu,P (MCP) is well-known for its high thermoluminescence (TL) sensitivity and is widely used for TL dosimetry. Following recent studies, highlighting its optically stimulated luminescence (OSL), the properties of MCP have been studied for OSL-based 2D and 3D dosimetry. Here, we have measured the spectrally resolved OSL emission as a function of stimulation time, identifying the peak of the emission band to be at ∼355 nm during the early stimulation period before shifting to peaking at ∼382 nm during the remaining part of the experiment. By assuming the spectra to originate from radiative recombination centers with Gaussian emission bands, we identified two recombination centers with emission centered at ∼355 nm (RC1) and ∼394 nm (RC2), respectively. From the OSL decay curves, we have identified two dominating types of OSL traps (fast and slowly decaying OSL traps). We provide indicative values for the photoexcitation cross section of these OSL traps. The fast-decaying OSL traps were found to predominantly emit OSL through RC1. By depleting the fast-decaying OSL traps before TL measurements, we have identified these traps to be associated with a previously undetected TL peak at ∼87 ° C (1 °C/s heating rate), located between the TL peaks usually denoted as peaks one and two. We further found that the features related to the fast-decaying OSL traps were not observable for powder samples without a heat treatment at ∼560–700 °C. Pellet samples show these features without the heat treatment, but could potentially have undergone a similar treatment during sintering.

Luminescence and thermoluminescence of Er3+-doped CaF2 nanomaterials

Er3+-doped calcium fluoride (CaF2:Er3+) nanoparticles (NPs) have been synthesized by a chemical co-precipitation method. A solution of water ethanol in a 1:1 ratio was used as a solvent. X-ray diffraction and scanning electron microscopy (SEM) results indicated that the fabricated material had a cubic crystal structure and a characteristic cubic shape of Caionscrystals. The main grain size calculated from Scherer’s formula was about 30 nm. The photoluminescence (PL) spectrum of the material showed the specific emissions of Er3+ ion in the CaF2 host lattice and the highest emission intensity was obtained at 2 mol% Er3+ ion. Under a 980 nm laser excitation, the up-conversion luminescence spectra with predominance of red emission were recorded. The thermoluminescence (TL) characteristics of the material were also studied. The obtained CaF2:Er3+ nanocrystals exhibit a high TL sensitivity and linearity to beta (β) radiation doses. The main TL peak is located at 235°C (508 K) and the kinetic parameters corresponding to the trap have been determined by TLAnal software These properties make the phosphor useful for application to estimate exposures of beta rays.

Synthesis, structural characteristics and thermoluminscence features of KCl:Mn and KCl:Ce phosphors

Manganese and cerium doped potassium chloride (KCl:Mn and KCl:Ce) were produced by the co-precipitation method with ultrasonic waves. Characterization of the samples material was carried out using X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS) patterns. The optimum amount of manganese and cerium concentration with the most thermoluminescence (TL) sensitivity was obtained at 0.3 mol% in KCl:Mn and 0.5 mol% in KCl:Ce samples. To evaluate the number of component glow peaks and the kinetic parameters of the TL glow curve of synthesized materials, computerized glow curve deconvolution (CGCD) and Tm-Tstop methods were used. The thermoluminescence properties of phosphors were studied at different doses. The TL response was linear in the range of 10–1000 Gy. Other TL features of the prepared material are also discussed.

Thermoluminescence analysis of beta particle irradiated Gd1-xEuxAlO3 phosphors

The suitable choice of an activator and host combination is essential for synthesizing very sensitive thermoluminescence phosphors. In addition, conspicuous synthesis variables must be optimized to achieve the maximal response. The research presented herein shows that the most recommendable conditions to improve the thermoluminescence response of beta irradiated Gd1-xEuxAlO3 phosphors were: x = 0.02 for europium stoichiometry and 1500 °C for the calcination temperature. The glow curve recorded for the most sensitive phosphor was partially erased by photo-bleaching, and thus, should yield optically stimulated luminescence.

Structural, compositional and luminescence studies of Y2O3:Eu3+ nanophosphor synthesized by sol-gel method

Europium doped Yttrium oxide (Y2O3) nanophosphors with different doping concentrations were synthesized by simple and efficient sol-gel method. The structural, morphological and compositional study was carried out by using XRD, FE-SEM, TEM, EDS, XPS, etc. Results demonstrated that the material is highly crystalline with cubic (body centered) structure and the particles apparently are of spherical shape with particle size around ∼10–20 nm. EDS results show the presence of Eu-impurity evenly distributed. Optimization of luminescence properties of the material by varying the concentration and annealing temperature show maximum thermoluminescence (TL) sensitivity at 1600 °C for 10.0 M% of Eu, however, maximum photoluminescence (PL) intensity was achieved after annealing the nanophosphor at 1200 °C. It exhibits a strong red emission with a sharp peak at 612 nm under excitation with UV and visible light (λex = 260, 393, 466 nm). TL studies showed four peaks at 100, 117, 139, and 301 °C. However, the first peak fades completely in a day (apparently due to low peak temperature) but the other three peaks are quite stable. The TL response was found to be linear from 120 Gy to 1.0 kGy but becomes sub-linear later in the dose range 1.0–100 kGy.

Low temperature luminescence and tunnelling effect in the Sr4Al14O25 co-doped with Eu2+and Dy3+ persistent luminescent phosphor

Thermoluminescence (TL) technique is very useful in the research of persistent Luminescence (PL) phosphors. It gives information about the existence of energy levels within the forbidden band and lifetime. The TL glow curve of Sr4Al14O25: Eu2+,Dy3+ persistent phosphor consists of two well-separated glow peaks at around 353 K and 438 K after both UV radiation and beta irradiation. To study the low temperature (≤ room temperature) glow peaks, low temperature TL (LTTL) measurements were performed with a homemade system after exposed to UV radiation. The sample was heated according to T(t)=T∞−(T∞−T0)e−αt equation starting from liquid nitrogen temperature, 77K. Besides the peaks at around 345 and 445 K according to LTTL results, Sr4Al14O25: Eu2+,Dy3+ has two more well-separated low temperature TL peaks at around 170 K and 295 K.The lifetime of the TL glow peaks (at 353 K and 438 K) was calculated according to s−1exp(EkT) and the results were checked with fading tests. Moreover, TL sensitivity tests were carried out both with and without preheating. Finally, tunnelling effect was evaluated by using the results of sensitivity tests and fading tests. Interesting results were observed at sensitivity tests performed with preheating. The results indicates that the behaviour of two glow peaks is very different from each other. The mechanism behind the peak around 438 K is localised transition involving a tunnelling effect.