Thermoluminescence Dose Response Research Articles

The thermoluminescent properties of lithium triborate (LiB3O5) activated by aluminium

In this paper, the thermoluminescence (TL) dosimetric characteristics of Al-doped LiB3O5 compounds are presented. The powder samples were prepared by the solid-state reaction method and the formation of the compounds were confirmed by an X-ray diffraction study. The TL studies of undoped and Al-doped LiB3O5 samples showed similar glow curve structures. They have three TL glow peaks at about 60, 130 and 200°C after heating at a constant heating rate of 1°C/s. Their comparative TL studies indicated that 5wt% Al-doped LiB3O5 compound was approximately 240 times more sensitive than undoped compound. The TL emission spectra of Al-doped LiB3O5 showed a maximum band at around 520nm. The main dosimetric characteristics, which are namely the TL dose response, TL sensitivity, fading, minimum detectable dose, reproducibility, precision of dose measurement and annealing procedure, indicated that Al-doped LiB3O5 sample, can be used in dosimetric applications. The trap parameters namely order of kinetics (b), activation energy (E) and frequency factor (s) associated with the glow peaks in beta irradiated undoped and Al-doped LiB3O5 samples were obtained by glow curve deconvolution (GCD) program.

Thermoluminescence properties of undoped and nitrogen-doped CVD diamond exposed to gamma radiation

It is known that the thermoluminescence (TL) performance of CVD diamond depends on the impurity concentration and doping materials introduced during growing. We report on the TL properties of undoped and 750 ppm nitrogen-doped CVD diamond grown on (0 0 1) silicon substrate. The samples were exposed to gamma radiation from a Gammacell 200 Nordion irradiator in the 10–500 Gy dose range at 627 mGy/min dose rate. The nitrogen-doped CVD diamond sample exhibited a TL glow curve peaked around 537 K and a small shoulder about 411 K and a linear dose behavior in the 10–60 Gy dose range. In contrast, the undoped specimen showed a 591 K peaked TL glow curve and linear dose response for 10–100 Gy doses. However, both samples displayed a non-linear dose response for doses higher than 100 Gy. The doping effects seem to cause a higher TL efficiency, which may be attributed to the differences in the diamond bonding and amorphous carbon on the CVD samples as well as to the presence of nitrogen. In addition, the nitrogen content may produce some structural and morphological surface effects, which may account for the distinctive TL features and dose response of the diamond samples.

Letters to the Editor

Sir, Comments to the author's response to our letter on ‘The thermoluminescence dose–response and other characteristics of the high-temperature TL in LiF:Mg,Ti (TLD-100)’ by Y. S. Horowitz, L. Oster and H. Datz. The response of Horowitz(1) to our comments(2) to the above-mentioned article(3) contains inaccuracies which must be addressed. We object to the response to our previous letter to the editor(2) in the following respects. Even the most ardent believer in his cause should take care not to ignore facts and thereby come to biased conclusions, especially in a scientific dispute. In the opening sentence of his response to our comments 1 and 2, Horowitz incorrectly ‘quotes’ our claim that ‘the high-temperature thermoluminescence (HTTL) dose response is consistent with linearity’(1). It is definitely not what we mentioned in point 2(2). We must stress again that our true claim is that, for the low dose range, the gamma non-linearity is not observable, being within the experimental uncertainties range, which is obviously a different view. This point is mentioned also by other authors, but Horowitz continues to disregard the works of others in the field of application of HTTL to dosimetry by taking again into account our examples to be the only relevant material and ignoring other articles published on the subject. Almost from the beginning of studying the thermoluminescence phenomenon and its application to dosimetry and up to the present days, this subject has been dealt with. A review on this issue(4) mentions 12 works on the applications of HTTL with 6LiF for thermal neutron fields alone, many other works refer to fast neutrons. Out of the 12 works mentioned, 8 were published in international journals. One work reports practical routine application, and an American patent on the subject was registered as well.

Letters to the Editor

Sir, Comments on ‘The thermoluminescence dose-response and other characteristics of the high-temperature TL in LiF:Mg,Ti (TLD-100)’ by Y. S. Horowitz, L. Oster and H. Datz This recent article(1) was intended to be a review on the subject and it reflects the view of its authors, as already published in the past. When discussing the dose–response issue (by gas and contact heating) the works of two groups (us being one of them) are discussed at length and in much detail, somewhat outside the scope of a balanced review. The article contains claims that are problematic and need to be discussed in depth, yet we find it important to present here some short comments on several issues raised, in particular the ones related to the chapter ‘HTTL dose-response via hot gas non-linear chip heating’, which is entirely dedicated to criticism of the experimental method in our works(...

The thermoluminescence dose response and other characteristics of the high-temperature TL in LiF:Mg,Ti (TLD-100)

Various characteristics of the high-temperature thermoluminescence (HTTL) in the glow curve of LiF:Mg,Ti (TLD-100) are reviewed. The proposed applications of the HTTL to mixed-field radiation dosimetry are outlined with special emphasis on the question of the linearity/supralinearity of the HTTL dose-response at low dose levels from 2.5 to 250 mGy. Recent measurements of the HTTL dose-response using non-linear hot-gas heating and linear planchet heating are discussed in detail. It appears that a mild HTTL supralinearity of approximately 15-50% for each dose decade may be present, followed by an abrupt and rapid increase in the supralinearity >250 mGy. However, difficulty in the estimation of background and the great variability in the protocols of measurement do not allow a definitive conclusion. There is much work to be done in the areas of protocol standardisation, materials selection, methods of data analysis and especially the details of background behaviour, and subtraction before the HTTL can become a reliable dosimetric tool.

Investigation of the stability of the radiation sensitivity of TL peaks of quartz extracted from tiles

One of the most important mineral in dosimetric investigation is quartz, which is found abundantly in archaeological and geological materials. Although there are many studies about its thermoluminescence (TL) properties in the literature, it may exhibit different properties for each quartz mineral extracted from the different region of the world. In the present work, the stabilities and dose responses of glow peaks of quartz obtained from the tiles of Kubad Abad Palace in central Turkey were investigated after annealing at 500 and 600 °C for 1 h. The variation of radiation sensitivity of TL peaks of the quartz grains extracted from tiles are found to be more stable after annealing at 600 °C than 500 °C for 1 h. The TL dose responses of glow peaks of annealed and unannealed quartz samples were also studied up to approximately 3 kGy. It was observed that the pre-irradiation heat treatments affect the dose response behaviors of glow peaks.

Thermoluminescence properties of Ce 3+-doped LiSr 4(BO 3) 3 phosphor

Borates LiSr 4(BO 3) 3 were synthesized by high-temperature solid-state reaction. The thermoluminescence (TL) and some of the dosimetric characteristics of Ce 3+-activated LiSr 4(BO 3) 3 were reported. The TL glow curve is composed of only one peak located at about 209 °C between room temperature and 500 °C. The optimum Ce 3+ concentration is 1 mol% to obtain the highest TL intensity. The TL kinetic parameters of LiSr 4(BO 3) 3:0.01Ce 3+ were studied by the peak shape method. The TL dose response is linear in the protection dose ranging from 1 mGy to 1 Gy. The three-dimensional thermoluminescence emission spectra were also studied, peaking at 441 and 474 nm due to the characteristic transition of Ce 3+.

A quantitative kinetic model for Al 2O 3:C: TL response to ionizing radiation

This paper presents a quantitative kinetic model for the important dosimetric material Al 2O 3:C. The model consists of two traps and two centers, and reproduces the experimental thermoluminescence (TL) vs. dose behavior, as well as the experimental variation of the optical absorption coefficient K with beta dose. Initial estimates of the kinetic parameters in the model are obtained either from published experimental data, or by using reasonable physical assumptions. Good agreement between the experimental data and calculations from the model are obtained for three different types of samples of alumina. This is achieved by keeping the trapping and recombination probabilities constant for all three samples, while the concentrations of the carriers are varied. The kinetic model provides also a quantitative description of the experimentally observed nonmonotonic behavior of the TL dose–response curves for all three samples.

The effects of annealing and irradiation on the sensitivity and superlinearity properties of the [formula omitted] thermoluminescence peak of quartz

Quartz samples which undergo heating and irradiation treatments exhibit changes in their sensitivity to irradiation, as well as in their TL dose response. These changes of thermoluminescence (TL) sensitivity and superlinearity of the 110 ∘ C TL peak of quartz have been the subject of several experimental and theoretical studies, because they form the basis of the predose technique for dating ceramics and for accident dosimetry. In an effort to separate experimentally the effects of irradiation and annealing on the predose effect, three quartz samples of different origin were prepared under three different conditions: unannealed samples, samples annealed at 500 ∘ C , and samples annealed at 900 ∘ C . Complete TL versus dose and sensitivity S versus predose curves were obtained for the dose range of 0.1 < D < 400 Gy . Additional complete sets of data were obtained for samples that underwent a combined predose irradiation and a heat treatment to 500 ∘ C . Although the TL versus dose curves and the sensitivity versus predose data showed very different behaviors, preannealing the samples at 900 ∘ C removed the observed differences that are due to the thermal or irradiation history of the quartz samples. The experimental data is consistent with the assumption that high-temperature anneals and/or high dose irradiation of the samples reduces the concentration of available competitor sites. The concentration of these competitor sites, as described by the Zimmerman model of quartz, is identified as the most important factor in causing the observed differences in predose behavior between quartz samples of different origin. Strong evidence in support of this competitor theory is provided by the estimated equivalent doses (EDs) for the three quartz samples.

Thermoluminescence glow curves and optical stimulated luminescence of undoped α-Al2O3 crystals

The characteristics of thermoluminescence (TL) and optical stimulated luminescence (OSL) in undoped alpha-Al2O3 single crystals were studied. The TL glow curves of the crystal samples irradiated at various dose levels were measured by RisØ TL/OSL-DA-15B/C reader with U-340 or 7-59 filters at different heating rates. The glow peaks measured with U-340 at approximately 210 degrees C of the undoped alpha-Al2O3 can be well fitted by first-order kinetic equation whereas the glow peaks measured with 7-59 filters are a composite of two first-order glow peaks. It indicates that the TL glow curves are dependent upon the filter used in the reader that is related to the emission spectra of luminescence materials. The OSL were also measured and fitted by two exponential functions to get the luminescence intensities. The TL and OSL dose responses of the undoped alpha-Al2O3 crystal were obtained in the dose range of 0.12-248 Gy and fitted by the composite action dose-response function to get nonlinear characteristic parameters. The TL and OSL dose responses are linear-sublinear.

Search for ionisation density effects in the radiation absorption stage in LiF:Mg,Ti

Optical absorption (OA) dose-response of LiF:Mg,Ti (TLD-100) is studied as a function of electron energy (ionisation density) and irradiation dose. Contrary to the situation in thermoluminescence dose-response where the supralinearity is strongly energy-dependent, no dependence of the OA dose filling constants on energy is observed. This result is interpreted as indicating a lack of competitive process in the radiation absorption stage. The lack of an energy dependence of the dose filling constant also suggests that the charge carrier migration distances are sufficiently large to smear out the differences in the non-uniform distribution of ionisation events created by the impinging gamma/electron radiation of various energies.

Defect complexes in Re3+-doped magnesium sulphate phosphors

A series of magnesium sulphate phosphors MgSO4:RE3+,X ( RE = Dy, Tm, Eu and X = P, Mn) have been prepared and studied. Based on the experimental results of thermoluminescence (TL) emission spectra and dose responses studies, it is proposed that in these phosphors large defect complexes are formed, which include intrinsic imperfections and dopants. These defect complexes were formed in the course of preparation of phosphors and could be regarded as basic elements in the TL multi-stage processes. This defect model might be applicable to the most of TL materials.

TL and OSL of SrSO4 phosphors doped with Eu

The thermoluminescence (TL) and optically stimulated luminescence (OSL) of SrSO4:Eu (0.1 mol%) powder sample were studied. The TL and OSL emission spectrum are measured after irradiation (absorbed dose 100 Gy) of 90Sr source; both of them showed that the emission wavelength is at approximately 375 nm, which indicates that TL and OSL have the same luminescence centres, and the luminescence comes from transitions between the energy levels of Eu2+. The TL glow curves and OSL decay curves illustrate that there is only one main TL peak but two main components in OSL curves. By a comparative study of TL and OSL it is concluded that OSL traps are different from TL traps. The TL and OSL dose responses of SrSO4:Eu phosphor were measured, and it showed that phosphor has similar dose responses for OSL and TL.

A comparative study of the anomalous fading effects of TL and OSL signals of Durango apatite

AbstractThe Thermoluminescence (TL), Blue Stimulated Luminescence (BSL) and Infrared Stimulated Luminescence (IRSL) properties of apatite (originating from Durango, Mexico) are studied. The TL dose response of Durango apatite is linear to an extended dose region whereas the BSL and IRSL dose responses are sublinear. The TL, BSL and IRSL signals are found to exhibit strong anomalous fading (AF). All experimentally obtained BSL and IRSL decay curves were transformed into pseudo‐linear modulated (pseudo‐LM) ones. The resulting glow‐curve shaped pseudo‐LM curves were analyzed using a deconvolution analysis, similar to that used for the glow‐curve deconvolution (GCD) of TL glow‐curves. It was found that the pseudo‐LM BSL and IRSL decay curves consist of two components termed fast and slow and their individual contributions were estimated. The AF of the remnant TL, BSL and IRSL signals as a function of storage time were fitted to the tunneling model equations and the fading rate g, in terms of percentage per decade was evaluated. According to the g values found the AF properties are ordered as following: The AF of the BSL and IRSL signals is stronger than that of the TL. The AF of the fast components of BSL and IRSL signals is almost the same. The stimulation by blue light causes strong bleaching of the TL signal and alterations in the glow‐curve shape, whereas the IR light causes, only, a slight bleaching of the TL signal without changes in the glow‐curve shape. (© 2006 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Thermoluminescence studies of rare earth doped Sr 2Mg(BO 3) 2 phosphor

The Sr 2Mg(BO 3) 2 phosphors doped respectively with Tm 3+, Tb 3+ and Dy 3+ as activator were prepared by high temperature solid-state reaction. All the thermoluminescence curves of the phosphors consisted of two isolated peaks and the Dy 3+ activated sample exhibited the strongest thermoluminescence intensity. The kinetic parameters of the thermoluminescence of Sr 2Mg(BO 3) 2 : 0.04 Dy were calculated employing the peak shape method and 3 dimensional thermoluminescent emission spectra were observed peaking at 480, 579, 662 and 755 nm due to the characteristic transition of Dy 3+. In addition, the pre-irradiation heat-treatment and the thermoluminescence dose response of Sr 2Mg(BO 3) 2 : 0.04 Dy were investigated.

Thermoluminescence properties of Chile Guajillo (paprika) Mexicano

The thermoluminescence properties of the inorganic dust extracted from the Chile Guajillo (paprika) Mexicano, were studied in order to verify the possibility of using the TL technique to discriminate between irradiated and non irradiated peppers. The inorganic dust was found to consist of quartz 60%, albite (NaAlSi 3 O 8 ) 30%, and ortose (KAlSi 3 O 8 ) 10%. Its thermoluminescence dose response covers the wide dose range of 1 Gy – 10 kGy , which was attributed mainly to feldspars. Its high sensitivity and its stability over 10 irradiation-readout cycles allow the application of a single grain–single aliquot regeneration dosimetry in Chile Guajillo (paprika). Evaluations based on trapping parameters show that thermal fading at room temperature for glow-peaks above 180 ∘ C, is not a problem in the dosimetry of paprika.

Thermoluminescence characteristics of BaB 4O 7:Dy phosphor

The polycrystalline powder samples of dysprosium-doped BaB 4O 7:Dy phosphor were prepared by a solid-state reaction in air at high temperature and the thermoluminescence (TL) glow curves and three-dimensional (3D) TL emission spectrum after 60Co gamma-ray irradiation was studied in the 20–130 kGy dose range at 293 K. The emission bands about at 480, 575, 660 and 750 nm were observed in the three-dimensional (3D) emission spectrum. The 3D TL emission spectrum of the BaB 4O 7:Dy is attributed to the characteristic emission from transitions of Dy 3+ ion. That no emission spectrum is observed for Dy 2+ ions is probably due to the emission wavelengths lying outside the measurement range. The distributions of traps produced by the irradiation of gamma-ray can be altered greatly by the change of the concentrations of Dy 3+ ion doped in BaB 4O 7 and peaks temperatures shift to higher temperature, this will be favorable for TL output. The depth of trap E of the main peak of BaB 4O 7:Dy is calculated as 1.38 eV. The influence of the 60Co gamma-ray irradiation doses on thermoluminescence of BaB 4O 7:Dy phosphor and the order of kinetics of TL glow peaks were also discussed. The TL–dose response of the BaB 4O 7:Dy polycrystalline powder sample to gamma-ray radiation in the range from 1 to 100 Gy for clinical dose levels is almost linearity. The experiment results showed that BaB 4O 7:Dy potential use as the materials of gamma-ray thermoluminescence dosimeter (TLD) for clinical dosimetry.

Thermo and mechanoluminescence of Dy3+ activated K2Mg2(SO4)3 phosphor

A solid state diffusion method for the preparation of (K 2 :Dy)Mg 2 (SO 4 ) 3 and (K 2 :Dy,P)Mg 2 (SO 4 ) 3 phosphors is reported. Thermoluminescence (TL) and mechanoluminescence (ML) characteristics are studied. TL, shown by the (K 2 :Dy,P)Mg 2 (SO 4 ) 3 phosphor is 60% as intense as the conventional CaSO 4 :Dy phosphor used in the TLD of ionization radiation. It has a linear TL dose response and a negligible fading. These properties of (K 2 :Dy,P)Mg 2 (SO 4 ) 3 should be suitable in dosimetry of ionization radiation using TL technique. ML of (K 2 :Dy)Mg 2 (SO 4 ) 3 shows one peak which has been observed in ML intensity versus time curve. The ML peak shows the recombination of electrons with free radicals (anion radicals produced by γ-irradiation) released from traps during the mechanical pressure applied on the Dy activated K 2 Mg 2 (SO 4 ) 3 phosphor. This ML mechanism is proposed for γ-irradiated sulfate based phosphors. It has been found that the total light output, i.e. ML intensity, increases with concentration of dopant, strain rate and irradiation dose of the phosphor. Mechanoluminescence and ML emission spectra of (K 2 :Dy)Mg 2 (SO 4 ) 3 were recorded for better understanding of the ML process. The TL and ML measurements have also been performed to elucidate the mechanism of ML. Some correlation between ML and TL has also been found.

Characterization of Al 2O 3 single crystals grown by the laser-heated pedestal growth technique for potential use in radiation dosimetry

Al 2O 3 single crystals were grown by the laser heated pedestal growth (LHPG) technique for potential use in radiation dosimetry using optically stimulated luminescence. The crystals were grown in the form of short single crystal fibers under a variety of growth conditions. Thermoluminescence (TL), radioluminescence (RL), cathodoluminescence, photoluminescence and optically stimulated luminescence (OSL) measurements were carried out on all fibers to assess their potential in luminescence radiation dosimetry. Measurements of luminescence spectra and the TL and OSL dose response characteristics lead to the suggestion that LHPG fibers have attractive luminescence dosimetry properties and warrant further study for potential applications in radiotherapy using OSL.

Localized transitions in the thermoluminescence of LiF : Mg,Ti: potential for nanoscale dosimetry

We describe the effect of nanoscale spatially coupled trapping centre (TC)–luminescent centre (LC) pairs on the thermoluminescence (TL) properties of LiF : Mg,Ti. It is shown that glow peak 5a (a low-temperature satellite of the major glow peak 5) arises from localized electron–hole (e–h) recombination in a TC–LC pair believed to be based on Mg2+–Livac trimers (the TCs) coupled to Ti(OH)n molecules (the LCs). Due to the localized nature of the e–h pair, two important properties are affected: (i) heavy charged particle (HCP) TL efficiency: the intensity of peak 5a relative to peak 5 following HCP high-ionization density irradiation is greater than that following low ionization density irradiation in a manner somewhat similar to the ionization density dependence of the yield of double-strand breaks (DSBs) induced in DNA. Our experimental measurements in a variety of HCP and fast neutron radiation fields have demonstrated that the ratio of glow peaks 5a/5 is nearly independent of particle species for the protons, deuterons and He ions investigated, is somewhat dependent on HCP energy, and is roughly 2–3 times greater than the peak 5a/5 ratio in low ionization density electron and photon fields. The intensity ratio of peak 5a/5 thus has the potential of estimating the ratio of dose deposited via high ionization density interactions compared to low ionization density interactions in a nanoscale volume without any prior knowledge of the characteristics of the radiation field, (ii) non-linear TL dose response: the relative lack of competitive processes in the localized recombination transitions leading to the TL of composite peak 5 versus the dose-dependent competitive processes in conduction band-mediated delocalized luminescence recombination leads to non-linear dose response (supralinearity) for composite peak 5 and a dependence of the supralinearity on ionization density. This behaviour is modelled in the framework of the unified interaction model (UNIM).