Search

OSL fading with storage time after irradiation remains a major obstacle in the development of ideal OSL materials. Dy and Eu co-doped NaMgF 3 are attractive candidates for various rare earth doped matrix materials. In this study, NaMgF 3 :Dy,Eu was synthesized by a solid-state reaction, and the effects of heating temperature, duration, atmosphere, and cooling rate on XRD, TL and OSL properties were studied. A simple, safe, efficient, and time-saving solid-state reaction was identified as a potential method for the preparation of NaMgF 3 :Dy,Eu, which could be optimally prepared by heating at 750 °C for 2 h under nitrogen atmosphere (2 l/min) followed by rapid cooling. The results show that NaMgF 3 :Dy,Eu has a more stable OSL response and an excellent TL glow curve, with only a 0.4% decrease in the OSL signal read after 1 d of dose irradiation compared to that immediately after irradiation, and a high main TL peak at ∼320 °C. It has been indicated the OSL signal in this material seems to be strongly related to the main TL peak. The material has a considerable OSL sensitivity and decay rate than the Luxel Detector. NaMgF 3 :Dy,Eu will have a promising future in the field of OSL dosimetry due to its near tissue equivalence, low OSL fading without preheating, fast OSL decay rate, and predictable and easily reusable dose elimination. • The effects of preparation processes of NaMgF 3 :Dy,Eu synthesized by solid-state method on OSL and TL were investigated. • The preparation process of NaMgF 3 :Dy,Eu with the OSL short-term fading low up to 0.4% was obtained. • The main TL peak is located at ∼320 °C. • The material has a considerable OSL sensitivity and a more rapid decay rate than the Luxel Detector. • The material will have a promising future in the field of OSL dosimetry. [ABSTRACT FROM AUTHOR]

In this paper, Lu 2.97 Al 5–x Ga x O 12 :Ce 0.03 (x = 0, 1, 2, 3) nanophosphors were synthesized using sol-gel method and calcined at 1100 °C for 3 h. The effect of Ga content on the structural, photoluminescence (PL), and notably thermoluminescence (TL) glow curve, dose response, repeatability and fading properties were investigated. X-ray diffraction (XRD) results indicated that all synthesized samples were crystallized in a pure garnet phase. The PL emission spectra exhibited a broad emission band corresponding to the 5 d → 4f (2F 5/2 , 2F 7/2) transition of Ce3+ ions in the garnet lattice. Furthermore, a significant decrease in emission intensity was observed upon increasing Ga content. The TL characteristics of nanopowders irradiated with β-rays revealed a significant effect of Ga content on the peak position, shape and intensities of TL Glow curves, which can be explained by the reduction of the energy gap and the distribution of trap levels. The dose response linearity in the range of 0.125–100 Gy was examined for different Ga content, revealing a good linear behavior for x = 0 and 1 Ga. Additionally, samples prepared with x = 0, 1, and 2 Ga exhibited a high level of repeatability across a batch of 10 samples. Also, fading studies were performed for 128 h and revealed strong fading in samples synthesized with x = 0 and 1 Ga. These results suggest potential applications of Lu 3 Al 5 O 12 :Ce and Lu 3 Al 4 Ga 1 O 12 :Ce in ionizing radiation dosimetry. • Lu 3 Al 5-x Ga x O 12 :Ce3+ (x = 0, 1, 2 and 3) nanophosphors were successfully synthesized using sol–gel method. • Thermoluminescence properties of prepared nanophosphors exhibited a strong dependence on Ga content. • Single garnet phase was obtained for all prepared nanophosphors. • Lu 3 Al 5-x Ga x O 12 :Ce 0.03 demonstrated a good linear behavior within the range 0.125–100 Gy for x = 0 and x = 1. • Nanophosphors prepared with Ga content of x = 0 and x = 1 displayed perfect repeatability and indicated a remarkably strong fading. [ABSTRACT FROM AUTHOR]

The use of luminescence signals from single mineral grains for optical dating has become a valuable and frequently utilised tool in Quaternary Geochronology. Single grain luminescence dating is particularly beneficial in complex depositional settings, however the ability to measure single grain signals also offers the opportunity to assess intrinsic luminescence properties of individual mineral grains. The use of spatially resolved luminescence technologies such as an electron multiplier charge coupled device is of benefit when making luminescence measurements at single grain scales because they allow stimulation with light emitting diodes, and this offers a number of key benefits related to stimulation power when it comes to the assessment of characteristics such as optically stimulated luminescence (OSL) decay rate and the calculation of parameters such as the fast ratio and photo ionisation cross-sections. In this paper, the intra- and inter-sample variability of sensitised single grain thermoluminescence (TL) and OSL signals is considered. A comparison between TL and OSL signals is undertaken, as well as calculation of the fast ratio, OSL component photo ionisation cross-sections, thermal stability, and characteristic dose for a suite of quartz samples from a range of geographic locations and depositional settings. For these heated signals, key findings include the lack of relationship between OSL signal intensity and dominance of the fast component, the fitting of two components (a fast and slow component) is the most common fit for single grain OSL signals, characteristic doses from fast dominated signals suggesting saturation at c. 150 Gy, and the identification of the ultrafast OSL component. Intra-sample variability across all measured parameters is observed, suggesting that for this suite of samples, variability is the norm rather than the exception, and that the intrinsic luminescence characteristics of quartz are variable and diverse. • EMCCD imaging used for measurement of single grain quartz luminescence signal properties • Photo ionisation cross-section values calculated from single grain quartz OSL signals • Although not common, the ultra-fast component is observed in some quartz OSL signals • Thermal stability measurements suggest general stability of the signals measured • Characteristic dose assessment suggests an upper D0 limit of ∼150 Gy for fast dominated signals [ABSTRACT FROM AUTHOR]

A study on retrospective dosimetry was performed using electronic personal dosimeters (EPDs) for reconstructing doses received by radiographic testing workers. The dosimetric properties of the thermoluminescence (TL) peak in the temperature range of 100–200 °C were investigated by measuring the TL of the resistors extracted from the EPDs in a darkroom environment. Results showed that this TL peak exhibited optimal dosimetric properties, with a minimum detectable dose as low as 13 mGy. To calculate the absorbed dose using the resistors, a simplified single aliquot regenerative (SAR) dose method using the TL peak was employed. The zero dose of the commercial EPD (model CLOVER) was determined to be 58 ± 72 mGy through the random selection of six EPDs. Additionally, a dose overestimation correction factor for compensating rapid sensitivity changes after TL measurement of the natural sample was calculated as 1.73 ± 0.09. Furthermore, it was observed that the TL signal faded exponentially to approximately 60% over a period of 12 weeks. Subsequently, retrospective dosimetry was performed by irradiating EPDs with a standard gamma ray dose of 1 Gy. The radiation exposure dose calculated from the TL peak of the resistors was found to be approximately 10% lower. These findings showed that the retrospective dosimetry with EPD can be utilized for accurately estimating the radiation exposure dose. • Retrospective dosimetry was performed using resistors in electronic personal dosimeters. • The thermoluminescence dosimetric properties of resistors were investigated. • Electronic personal dosimeters are potentially suitable for retrospective dosimetry. [ABSTRACT FROM AUTHOR]

Opercula of the gastropod Bithynia tentaculata are composed of calcite, and are typically 2–4 mm in length. They emit a thermoluminescence (TL) signal that can be used for dose reconstruction, and spatially resolved TL data from them can be obtained using an electron multiplying charge coupled device (EMCCD). However, when multiple measurements are made of the same sample with imaging detectors such as the EMCCD, registering the different images is crucial so that when regions of interest (ROI) are defined they consistently relate to the same part of the specimen. Previous work on opercula has undertaken this registration by hand, but this is prohibitively time consuming and is also potentially prone to human error. An automated registration process is described, and its use is illustrated using a dose recovery experiment. Without registration more than half of the regions of interest defined across the operculum failed the recycling test, and for those ROIs which did pass recycling the dose recovery ratio varied from 0.7 to 1.2. After registration more than 97% of ROIs passed recycling and all these ROIs gave dose recovery ratios within two sigma of unity. The automated registration process described here has potential for application to other types of solid sample such as rock slices provided they are not perfectly circular. • Imaging detectors providing new insights for dosimetry. • Registration of images essential for accurate spatially resolved analysis. • Automated image registration described for calcitic opercula. [ABSTRACT FROM AUTHOR]

Abstract Durango apatite is a material that exhibits very strong athermal fading (AF) of luminescence signal. In this study, the EPR signals of natural Durango apatite in various different grain dimensions (ball milled for various durations up to 48 h and microscale grain size) were studied. The obtained EPR signal at room temperature yielded three different components with g values 2.0534 (hole center), 2.0398 (hole center) and 1.9920 (electron center). These components were observed for the reference grain size fraction of 100–180 μm; however, prolonged ball milling erases the two hole centers. The behaviour of all obtained components was investigated by step annealing processes (a) between room temperature and 400 °C in steps of 25 °C for 5 min and (b) between 400 °C and 1100 °C, in steps of 100 °C for 1 h. The EPR component with g value 1.9918 was almost totally removed until 1100 °C, while those with g values 2.0534, 2.0398 were erased after annealing at 500 °C and 400 °C respectively. The fading of EPR components was investigated for each ball milling (BM) and microscale grain size independently, at different storage times between 0 and 1000 min. Based on the results of fading and step annealing studies, the EPR component with g value 2.0398 could be directly correlated to the main dosimetric TL trap, while the component with g value 1.9920 appears to be responsible for TA – OSL signal for microscale grain size apatite, corresponding thus to a very deep trap. The behaviour of remnant EPR signal versus storage time could be successfully described by equations based on quantum mechanical tunnelling mechanism. Highlights • EPR signal of Durango apatite (grain size fraction of 100–180 μm) yields three different components at RT. • After ball milling, only one EPR component is monitored; the other two disappear. • EPR component with g = 1.9920 could be correlated to VDTs, as the origins of TA – OSL signal, based on thermal cleaning and athermal fading results. • EPR component with g = 2.0398 could be correlated to the main dosimetric TL trap. [ABSTRACT FROM AUTHOR]

Abstract A historical radium (226Ra) needle was found in a building in Prague. The needle was concealed in a wall under a window frame. Ambient dose equivalent rate measured in close proximity to the frame reached up to 2 mSv/h. The place was located between a corridor and a staircase where people normally did not stay; hence, any significant radiation exposure was not suspected. Because of a remarkable history of the building, our speculation was that the needle could have been concealed there during World War II. To verify this assumption, one adjacent brick nearest to the place of the find was removed. The brick was used for retrospective dosimetry based on optically stimulated luminescence (OSL) of quartz extracted from a chosen brick block. Dose rate values inside the brick block were determined by a laboratory reconstruction. The original exposure conditions were simulated using the needle and a brick wall containing thermoluminescence detectors (TLDs). We also performed a computational simulation with the Monte Carlo technique. The simulation provided us a more detailed dose rate distribution inside the brick block. Finally, we compared OSL quartz, TLD, and Monte Carlo results. A good agreement among the results supports the speculation that the radium needle was concealed during World War II. Highlights • A historical radium (226Ra) needle was found in a wall. • A brick was used for dose reconstruction based on optically stimulated luminescence (OSL) of quartz. • Dose rate values inside the brick block were determined by a laboratory reconstruction with thermoluminescence detectors (TLDs). • Dose distribution was calculated using the Monte Carlo technique. • OSL, TLD, and Monte Carlo results were in a good agreement. [ABSTRACT FROM AUTHOR]

Dental ceramics are radiation sensitive materials and exhibit luminescent properties. Their samples can be potentially used for individual dose assessment in situations where retrospective dosimetry is required. In this work, we investigated dosimetry properties of two leucite glass-based dental ceramics using Optically Stimulated Luminescence (OSL) and Thermoluminescence (TL). We concentrated on characteristics as reproducibility, fading, optical bleaching, minimum detectable dose (MDD), dose response and photon energy response of TL and OSL signals. Both the dental ceramics exhibited very good reproducibility (<5% at 2σ level) when irradiated and measured repeatedly. Their luminescence response was found to be linear for a wide range of doses up to 8.5 Gy. The MDD values for the samples investigated were a few mGy. The ceramics are not tissue equivalent materials, and their luminescent signals measured were strongly dependent on incident photon energy. Because of fading and optical bleaching the OSL and TL signals were not stable in time. Especially optical bleaching represents a main limiting factor for dose reconstruction. However, one of the ceramics provided a relatively resistant high temperature TL peak for dosimetry. [ABSTRACT FROM AUTHOR]

The decrease of the luminescence efficiency with increasing temperature is known as the thermal quenching effect. Various materials exhibit thermal quenching, among which quartz and AI 2 O 3 :C stand as the mostly well known. BeO, which is used generally as OSL dosimeter, has been reported to undergo thermal quenching effect; so far in the literature only one thermal quenching parameter was determined using various OSL techniques. This study is the first attempt in the literature to calculate both W and C thermal quenching parameters. TL glow curves of BeO ceramic chips were studied as a function of heating rates ranging between 0.25 K/s and 8 K/s. The procedure of analysis includes various steps dealing with de-convolution of the quenched TL glow curves, correction for temperature lag, evaluation of the experimental thermal quenching parameter values, reconstruction as well as de-convolution of the reconstructed TL glow curves. The reconstruction step is really important, while its aim is twofold: (a) to provide the most stringent criterion for selecting the physically meaningful W , C values for BeO and (b) to check the kinetic parameters of the unquenched glow curve. The first peak of BeO is not affected by the thermal quenching, while both second and third peaks suffer from thermal quenching. W and C parameters were determined as 0.54–0.66 (±0.07) eV, 1.8 · 10 5 –2.4 · 10 6 (±4 · 10 5 ) for peak 2 and 0.74–0.86 eV and 2.8 · 10 6 –2.1 · 10 7 for peak 3 respectively for U-340 filter by using indirect fit method. The same process was applied for BG-39 filter and W and C parameters were compared to those found through U-340 filter. The values for the main dosimetric peak 2, are independent on the detection filter used, as well as in great agreement with the W values previously reported in the literature. The difference in the W, C parameters for those two peaks in BeO provide a strong argument to the fact that each one of these two peaks uses different recombination centers. According to the results of the de-convolution before and after the reconstruction, it is indicated that the influence of the thermal quenching is mainly reflected to the value of the activation energy for the case of peak 3, which is under-estimated without reconstruction. [ABSTRACT FROM AUTHOR]

A new Dy doped CaNa 2 (SO 4 ) 2 nanophosphor has been synthesized using simple co-precipitation method and claimed to have good Thermoluminescence (TL) dosimetric properties. Structural, morphological, optical, compound identification and thermal analysis of the nanophosphor was studied by X-ray diffraction (XRD), High-Resolution Transmission electron microscope i.e. (HRTEM), UV–Visible, FTIR and TGA-DSC techniques. XRD studies showed a monoclinic structure and size of the particle found to be around ∼45 nm. HRTEM confirms the nanosize of the particles of the same order and SEAD pattern shows fringes perfectly match with inter planner spacing distance “d” of XRD i.e. 2.74 Å. UV–Visible and FTIR analysis revealed the absorption wavelength 246 nm which corresponds to the band gap of around ∼5.03 eV and formation of the compounds of different bonds such as S-O, S=O, SO 4 stretch, S S disulfide, respectively. The percentage of weight loss-gain, endothermic changes of the nanophosphor was measured using TGA-DSC analysis and corresponding weight loss of such a nanophosphor with increasing temperature was observed around 12.60%. The TL analysis shows that the CaNa 2 (SO 4 ) 2 :Dy has a typical single glow curve at 164 °C and gives excellent linear response curve over a wide range of gamma dose from 10 Gy to 10 kGy. Moreover, the reproducibility of the CaNa 2 (SO 4 ) 2 :Dy nanophosphor did not change after numerous cycles of exposures and readouts. Fading has been observed at around 9.55% for 30 days. Theoretical analysis of glow curves of samples irradiated by γ-rays was done by computerized glow curve deconvolution (CGCD) method to find out trapping parameters of various peaks. Finally, CaNa 2 (SO 4 ) 2 :Dy nanophosphor could be a potential candidate for applications in the field of accidental and reactor dosimetry. [ABSTRACT FROM AUTHOR]

This paper reviews recent research on the application of the physical dosimetry techniques of electron paramagnetic resonance (EPR) and luminescence (optically stimulated luminescence, OSL, and thermoluminescence, TL) to determine radiation dose following catastrophic, large-scale radiological events. Such data are used in dose reconstruction to obtain estimates of dose due to the exposure to external sources of radiation, primarily gamma radiation, by individual members of the public and by populations. The EPR and luminescence techniques have been applied to a wide range of radiological studies, including nuclear bomb detonation (e.g., Hiroshima and Nagasaki), nuclear power plant accidents (e.g., Chernobyl), radioactive pollution (e.g., Mayak plutonium facility), and in the future could include terrorist events involving the dispersal of radioactive materials. In this review we examine the application of these techniques in ‘emergency’ and ‘retrospective’ modes of operation that are conducted on two distinct timescales. For emergency dosimetry immediate action to evaluate dose to individuals following radiation exposure is required to assess deterministic biological effects and to enable rapid medical triage. Retrospective dosimetry, on the other hand, contributes to the reconstruction of doses to populations and individuals following external exposure, and contributes to the long-term study of stochastic processes and the consequential epidemiological effects. Although internal exposure, via ingestion of radionuclides for example, can be a potentially significant contributor to dose, this review is confined to those dose components arising from exposure to external radiation, which in most studies is gamma radiation. The nascent emergency dosimetry measurement techniques aim to perform direct dose evaluations for individuals who, as members of the public, are most unlikely to be carrying a dosimeter issued for radiation monitoring purposes in the event of a radiation incident. Hence attention has focused on biological or physical materials they may have in their possession that could be used as surrogate dosimeters. For EPR measurements, in particular, this includes material within the body (such as bone or tooth biopsy) requiring invasive procedures, but also materials collected non-invasively (such as clippings taken from finger- or toenails) and artefacts within their personal belongings (such as electronic devices of which smart phones are the most common). For luminescence measurements, attention has also focused on components within electronic devices, including smartphones, and a wide range of other personal belongings such as paper and other polymer-based materials (including currency, clothing, bank cards, etc .). The paper reviews progress made using both EPR and luminescence techniques, along with their current limitations. For the longer-established approach of retrospective dosimetry, luminescence has been the most extensively applied method and, by employing minerals found in construction materials, it consequently is employed in dosimetry using structures within the environment. Recent developments in its application to large-scale radiation releases are discussed, including the atomic bomb detonations at Hiroshima and Nagasaki, fallout from the Chernobyl reactor and atmospheric nuclear bomb tests within the Semipalatinsk Nuclear Test Site and fluvially transported pollution within the Techa River basin due to releases from the Mayak facility. The developments made in applying OSL and TL techniques are discussed in the context of these applications. EPR measurements with teeth have also provided benchmark values to test the dosimetry models used for Chernobyl liquidators (clean-up workers), residents of Semipalatinsk Nuclear Tests Sites and inhabitants of the Techa River basin. For both emergency and retrospective dosimetry applications, computational techniques employing radiation transport simulations based on Monte Carlo code form an essential component in the application of dose determinations by EPR and OSL to dose reconstruction problems. We include in the review examples where the translation from the physical quantity of cumulative dose determined in the sampled medium to a dose quantity that can be applied in the reconstruction of dose to individuals and/or populations; these take into account the source terms, release patterns and the movements of people in the affected areas. One role for retrospective luminescence dosimetry has been to provide benchmark dose determinations for testing the models employed in dose reconstruction for exposed populations, notably at Hiroshima and Nagasaki. The discussion is framed within the context of the well-known radiation incidents mentioned above. [ABSTRACT FROM AUTHOR]

The motivation of this work was to produce crystals of CaSO 4 doped with an unusual combination of RE elements such as terbium (Tb) and europium (Eu) in different concentrations, and analyze its thermoluminescent (TL) properties. The crystals were produced by the slow evaporation route using calcium carbonate (CaCO 3 ) as precursor, and incorporating the dopants (Tb 2 O 3 and Eu 2 O 3 ) in a solution of sulfuric acid, that is evaporated and collected again, leaving just CaSO 4 :Tb,Eu crystal powder. The terbium and europium ions were incorporated in concentration ratios of 1:1, 2:1 and 5:1 (weight proportions). X-ray diffraction analyses showed that samples of doped CaSO 4 exhibit only a single phase corresponding to the crystal structure of anhydrite. The radioluminescence confirmed the presence of Tb 3+ and Eu 2+ in the crystal matrix. The CaSO 4 :Tb,Eu crystal powders showed TL emission glow curves with three peaks centered around 170 °C, 270 °C and 340 °C, after irradiation with a 90 Sr/ 90 Y source. Thermoluminescent (TL) characteristics such as linearity, reproducibility and fading were evaluated. Samples produced with concentration ratio of 2:1 of Tb and Eu showed the highest TL intensity. The produced CaSO 4 :Tb,Eu samples present TL properties useful for dosimetric purposes. [ABSTRACT FROM AUTHOR]

Thermally assisted optically stimulated luminescence (TA-OSL) method is an excellent advancement of high-dose luminescent dosimetry with involvement of very deep traps. This specific method has been reported to be very efficient for the cases of anion deficient alumina doped with carbon and quartz. Nevertheless, reproducibility and sensitivity changes have been previously studied only for the case of quartz. In the present study, reproducibility was studied in both terms of quantitative and qualitative features, such as signal intensity and glow curve shape respectively, for both TL and TA-OSL signals on various TLD 500 dosimeters. Finally, for the case of the TL signal, sensitivity changes were studied with and without applying TA-OSL, towards studying the impact of the TA-OSL on the main dosimetric TL signal. [ABSTRACT FROM AUTHOR]

In the recent years, intensive research on the application of optically stimulated luminescence (OSL) from alumina rich electronic components, such as resistors and inductors of electronic gadgets, is being carried out for retrospective dosimetry in the event of radiological accidents or terroristic attacks. It was noted that in inductors of mobile phones, the OSL readout did not significantly affect the thermoluminescence (TL) signal of glow peaks above 200 °C which exhibited negligible fading. This effect was exploited to re-estimate the doses by using TL signal (“residual TL”) of the inductors and the resistors which were already subjected to OSL readout for the estimation of the given doses. The dose response of the residual TL signal was also found to be linear up to about 4 Gy for both the inductors and resistors. The estimation of doses by using OSL and the re-estimation by using residual TL was carried out for the nominal doses of 300 mGy, 1700 mGy and 3300 mGy. The estimated doses and the re-estimated doses were in the range of about 80%–97% of the nominal doses for the inductors and in the range of about 76%–111% for the resistors. It was concluded that the residual TL could be used for the re-estimation of doses in some cases of radiological accidents. [ABSTRACT FROM AUTHOR]

Thermoluminescence (TL) response of h-BN micropowder, characterized by two peaks near 337 and 584 K, was studied in the 380-nm band after excitation with monochromatic ultraviolet radiation (UVR). On the basis of the obtained results and independent data analysis, assumptions were made on the mechanisms of donor–acceptor recombination with the participation of 1B, O N, and C N centers, responsible for the observed thermally activated emission. TL excitation spectra in the 200–380-nm range were analyzed. It was observed that the resolved maxima correspond quite to the characteristic wavelengths of 260 nm (maximum bactericidal efficiency) and 297 nm (maximum skin erythema). It is found that the dose dependence for an integral intensity of high-temperature peak is linear in the suberythemal range of 0.01–0.35 mJ/cm 2 . [ABSTRACT FROM AUTHOR]

Efforts are aimed at finding a method that could serve TL dosimetric measurements in the range of low-dose but carried out in an environment with elevated temperature. The temperature at the position of the maximum intensity of LiF:Mg,Cu,P was about 280 °C when annealed at 460 °C. LiF:Mg,Cu,P with a maximum intensity at 280 °C should present good thermal stability. The TL intensity of LiF:Mg,Cu,P with a maximum intensity at 280 °C was about 54% of the standard LiF:Mg,Cu,P, it should have a minimum measurable dose in the range of micro-Gy. LiF:Mg,Cu,P with a maximum intensity at 280 °C could be re-used by the 660 °C/30 min annealing, followed by 270 °C/20 min, 240 °C/10 min and 460 °C/30 min. It's possible for LiF:Mg,Cu,P to be extended application for low dose test in an environment with elevated temperature. [ABSTRACT FROM AUTHOR]

This paper reports the Electron Spin Resonance (ESR) and Thermoluminescence (TL) dosimetric and kinetic characteristics of commercial watch glass. Both of the ESR and TL response of the watch glass sample yielded linear behavior in the 0.5–135 Gy gamma dose range. ESR dosimetric properties of watch glass sample like dose-rate dependence, signal reproducibility and fading behavior have also been studied in detail. Kinetic behavior and activation energy of the radiation induced free radicals responsible from the ESR spectra of watch glass sample were determined. The TL kinetic parameters such as activation energy (E), frequency factor (s), order of kinetics (b) were also calculated by applying the methods of initial rise (IR), isothermal decay (ID), variable heating rate (VHR) and de-convolution. [ABSTRACT FROM AUTHOR]

LiMgPO 4 (LMP) crystals were grown by micro pulling down technique. Samples were irradiated with different β-particle doses of the 90 Sr/ 90 Y source. Thermally and optically stimulated luminescence spectra were measured with the automatic Risø TL/OSL-DA20 reader under the different modes of stimulation. The dose–response dependence, reproducibility, the lowest measurable dose and short-time fading were investigated. TL and OSL dose–response of LiMgPO 4 crystals was found to be linear up to around 1 kGy, what makes this material suitable for high dose measurements. Discrepancies between successive measurements did not exceed 10%, regardless of the applied growth parameters. The lowest measurable dose, defined as three standard deviations of the signal of unexposed detector, was determined around 0.5 mGy. About 73% of the initial OSL signal value was measured 24 h after the irradiation. For longer periods of time the level of signal stabilizes so that there was no further loss of signal observed. In case of TL, the level of signal does not stabilize and decreases to 69% within 2 weeks after the irradiation. The obtained results tend to suggest that LiMgPO 4 crystals may be considered as promising dosimeters for both personal and high dose dosimetry. [ABSTRACT FROM AUTHOR]

This contribution presents a variety of different luminescence emission spectra from sedimentary feldspar and quartz samples under various stimulation modes. These are green stimulated quartz (OSL-) spectra, quartz TL spectra, feldspar IRSL and post-IR IRSL spectra. A focus was set at recording OSL and IRSL spectra at elevated stimulation temperatures such as routinely applied in luminescence dating. This was to test whether optical stimulation at elevated temperatures results in a shift of emission peaks. For OSL emissions of quartz, this has so far not been tested. In case of feldspar emissions, post-IR IRSL conditions, hence IRSL emissions at a low temperature, directly followed by high temperature post-IRSL emissions, are explicitly investigated. All spectra were recorded using a new system incorporated into a Lexsyg luminescence reader. Thus, this study, besides presenting new spectral data, also serves as a feasibility study for this new device. It is shown that (a) the new device is capable of automatically measuring different sorts of spectra, also at elevated temperatures, (b) known thermally and optically stimulated peak emissions of quartz and feldspar are confirmed, (c) obtained IRSL and OSL spectra indicate that there is no significant relation between peak emission and stimulation temperature. [ABSTRACT FROM AUTHOR]

In recent years opercula of the snail species Bithynia tentaculata have been shown to emit thermoluminescence (TL) signals that can be used to determine equivalent dose, and may be capable of dating events throughout the entire Quaternary period. Concentric growth lines are a notable feature of almost all B. tentaculata opercula, but it is not known whether the luminescence emitted by the opercula is influenced by these structures. This study uses a newly developed EMCCD imaging system to measure the TL signals from opercula. A combination of microscopic analysis of the opercula using visible imagery, and measurement of the TL using the EMCCD system has been undertaken. Variations in TL intensity and equivalent dose (D e ) are seen, but the two are not correlated. Changes in TL intensity broadly mimic the concentric growth structures, but the largest variations in intensity are between different margins of the opercula, not individual growth bands. The EMCCD system makes it possible to produce a two dimensional map of the D e measured from an operculum. Dose recovery experiments give D e values that are consistent with each other across the whole opercula. Measurement of the D e arising from irradiation in nature shows significant variability across a single operculum, but at present the reason for this variability is unknown. [ABSTRACT FROM AUTHOR]

Isothermal thermoluminescence (ITL) and thermoluminescence (TL) signals from quartz were studied. A single aliquot regenerative dose protocol has been applied for ITL D e determination (SAR-ITL). In the SAR-ITL protocol, the preheat condition was a cutheat to 10 °C higher than measurement temperature. The test dose was approximate to the expected D e , and a 450 °C heat was given at end of each cycle to minimize signal build-up. Based on signals strength and dose recovery test, temperatures of 235 and 255 °C were selected for the ITL D e measurement. A multiple aliquots regenerative protocol has been applied for TL D e determination (MAR-TL). The preheat procedure was a cutheat of 235 °C and a second glow TL of 175 Gy was used for normalization. The sensitivity change of first heating to 450 °C was negligible, supported by comparison between additive and regenerative dose growth curves. Based on the natural TL signal and preheat condition studies, D e values at temperatures of 250–330 °C were used for thermochronological study. These two protocols were applied to rock samples collected at different elevations from Nujiang River (also called Salween River) valley slope. The SAR-ITL gave D e results consistent with the MAR-TL at temperatures of 40–50 °C higher. The results clearly demonstrate the differences in the thermal histories between the analyzed samples. The SAR-ITL and MAR-TL protocols were both found to be suitable for application in thermochronology. [ABSTRACT FROM AUTHOR]

Here we compare the performance of an EMCCD-based imaging system with the standard laser-based single-grain Risø attachment. We first compare gamma dose distributions and the relative sensitivity of the two instruments is investigated using a single sample, by comparing the number of grains accepted into a dose distribution. EMCCD cross-talk is shown to be of concern at low light levels. We also make use of the fact that the EMCCD can observe TL signals from individual grains to examine the use of the correlation between the quartz 110 °C TL peak and the fast component OSL signal to correct for sensitivity change. Finally, we present the OSL dose distributions from a set of both well-bleached and poorly-bleached sedimentary samples. From a comparison of the measured doses, we conclude that the two instruments give indistinguishable dose estimates and dispersions, despite the fact that the laser-based system is effectively about four times as sensitive as the EMCCD. [ABSTRACT FROM AUTHOR]

In the present study, certain natural silicate minerals such as aquamarine (AB), morganite (PB), goshenite (WB), white jadeite (JW), green jadeite (JG), pink tourmaline (PT) and two varieties of jadeite-like quartz, denoted here by JQ1 and JQ2, were investigated using the thermoluminescence technique to evaluate their potential for use as very-high- and high-dose dosimeters. These minerals respond to high doses of γ-rays of up to 1000 kGy and often to very high doses of up to 3000 kGy. The TL response of these minerals may be considered to be satisfactory for applications in high-dose dosimetry. Investigations of electron paramagnetic resonance and optically stimulated luminescence dosimetry are in progress. [ABSTRACT FROM AUTHOR]

This work evaluates the dosimetric properties of crystals of CaSO 4 doped with unusual elements, such as europium (Eu) and silver (Ag), including their nanoparticle forms, after the incorporation of glass or Teflon and compares them with well-known thermoluminescent dosimeters (TLD). X-ray diffraction analyses showed that samples of doped CaSO 4 exhibit only a single phase corresponding to the crystal structure of anhydrite. Optical spectroscopy confirmed the presence of Eu 3+ in the crystal matrix and a luminescent gain due the presence of silver nanoparticles. The composites showed thermoluminescent emission glow curves, with a single peak centered at approximately 200 °C for pellets with Teflon and at 230 °C for pellets with glass. The dosimeters based on calcium sulfate doped with europium and silver nanoparticles provided the most intense thermoluminescent (TL) emission of the composites studied. In comparison with commercial TLD, such as LiF:Mg,Ti and CaSO 4 :Dy, the CaSO 4 :Eu,Ag(NP)+glass produced in this work presented similar low detection limits and higher sensitivity. The new methods for the preparation of dosimeters and the incorporation of glass are shown to be viable because all of the samples presented a linear, reproducible and first order kinetic TL emission. [ABSTRACT FROM AUTHOR]

In this work we evaluate the intensity and the spectral shape of the leakage radiation from the built-in beta and alpha sources of a Risø TL/OSL reader. LiF (TLD-100), fluorite-based pellets and Al 2 O 3 :C detectors were used in order to determine the dose rate delivered to the dosimeters when the sources are closed. The leakage spectra under both alpha and beta sources were registered with a CdTe semiconductor detector. The spectrum measured under the beta source shows the X-ray beam generated by the interaction of the beta particles with the lead used to shield the source. Besides, the 59.4 keV gamma ray from 241 Am was registered under the alpha source. Dose rates from 50 to 100 μGy/h were obtained for the dosimeter positions in the turntable under the beta and the alpha sources with the luminescent dosimeters. [ABSTRACT FROM AUTHOR]

Mobile phones are carried by a large part of the population and previous studies have shown that they may be able to function as individual fortuitous dosimeters in case of radiological accident. This study deals with thermoluminescence (TL) properties of mobile phone screen glass. The presence of a significant background signal which partially overlaps with the radiation-induced signal is a serious issue for dose reconstruction. A mechanical method to reduce this signal using a diamond grinding bit is presented. An over-response at low energy (∼50 keV) is observed for two investigated glasses. The results of a dose recovery test using a single-aliquot regenerative-dose (SAR) procedure are discussed. [ABSTRACT FROM AUTHOR]

The dependence of LiF:Mg,Cu,P samples with various concentrations of Mg on sintering temperatures was investigated to find a new dosimeter. The influence of high sintering temperatures on LiF:Mg,Cu,P chips depends strongly on Mg concentrations. The height of the main peak versus the sintering temperatures exhibits a maximum, the position of which varies between 690 °C and 750 °C, depending on the Mg concentration in the range studied. The high temperature peaks of LiF:Mg,Cu,P for various Mg concentrations reduce basically when the sintering temperature is increased. LiF:Mg,Cu,P is much less sensitive than LiF:Mg,Cu,Si to sintering temperature. LiF:Mg,Cu,P with 0.6 mol% of Mg can be re-used at annealing temperature of 260 °C, regardless of the sintering temperature. It was found that the optimum concentration is Mg: 0.6 mol%, the optimum sintering temperature is 750 °C, considering that LiF:Mg,Cu,P with a low residual signal and good sensitivity can be re-used at annealing temperature of 260 °C and produced in a large scale. The new optimum LiF:Mg,Cu,P formation has 52 times higher than that of the TLD-100, and an extremely low residual signal of 0.07% without an initialization readout procedure. [ABSTRACT FROM AUTHOR]

The influence of various annealing treatments with heating temperatures (T A ) from 240 to 700 °C, with re-annealing at 240 °C, and with a combined re-annealing procedure of 20 min at 270 °C followed by 10 min at 240 °C on LiF:Mg,Cu,P (GR-200A) was investigated. As the T A increased, the intensity decreased rapidly to almost no signal at 340–380 °C then increased clearly and achieved a maximum at 540 °C. The position of the maximum intensity of the glow curve shifted basically in the direction of higher temperatures with an increase at T A and achieved a maximum of 279 °C when annealed at 460 °C. The re-annealing influenced both the intensity and the glow curve structure at certain degree. The effect of re-annealing on the glow curve depended markedly on the T A . With re-annealing at 240 °C, the intensity decreased as T A increased up to 360 °C then increased and achieved a maximum at 540 °C. The intensity could be restored fully when annealed at above 500 °C, however, the glow curve couldn't be restored fully. With a combined annealing, the shape of glow curve of a sample annealed at above 540 °C or below 320 °C was similar to that of the standard glow curve of LiF:Mg,Cu,P and the intensity and glow curve could be restored completely when annealed in the range 620–660 °C. It seems that the main roles of the re-annealing at 240 °C are to restore partially the intensity of peak 4 and peak shape for LiF:Mg,Cu,P when annealed at above 260 °C, and restore fully the total TL intensity of LiF:Mg,Cu,P when annealed at above 500 °C and the main roles of the combined re-annealing are to reduce the intensity of peak 5 and the total TL intensity, increase the intensity of peak 4 and restore the glow curve shape. [ABSTRACT FROM AUTHOR]

Abstract: The pre-dosed thermoluminescence (TL) emission of quartz has been found to be useful in retrospective dosimetry and archaeometry. Though the pre-dosed optically stimulated luminescence (OSL) and TL emissions have been reported to be similar, the former has been found to be un-reliable for the equivalent dose estimation. As this measurement protocol involves thermal heating at around 400 °C, the work reported in this paper investigated the influence of this heating on the OSL using fired specimens from various regions. The results suggested that the discrepancy in the behaviour of two emissions is caused by the presence of the thermally transferred optically stimulated luminescence (TT-OSL) induced by thermal-activation involved in the pre-dose treatment. This transferred signal was observed to be very significant in the case of samples containing a prominent higher-temperature TL peak at ∼375 °C. The characterization of this signal based on (i) the nature of the glow curves, (ii) thermal-annealing of the OSL trap, (iii) observation of the TT-OSL, (iv) bleaching of the source trap and (v) the correlation between TL and OSL seems to suggest that the trap corresponding to this TL peak is the source trap in the TT-OSL emission mechanism. [Copyright &y& Elsevier]

Optically stimulated luminescence (OSL) signals from individual quartz grains are frequently used for equivalent dose and age determination in luminescence dating. Typically, signals from individual grains are stimulated with a focussed solid-state laser and detected via a photomultiplier tube. In contrast to the light-emitting diodes (LEDs) usually used when stimulating multiple-grain aliquots, the laser has a much higher stimulation power density. An absolute value for the effective stimulation power cannot easily be quantified, and the power delivered to each grain cannot be considered consistent throughout a measurement sequence. Both intra- and inter-sample variability in single grain luminescence signals parameters such as dose response form, decay rate, and sensitivity have long been recognised, however there remains uncertainty over how much of this variability is intrinsic to quartz grains or whether some should be attributed to variation in the effective stimulation power associated with the laser system. To better characterise intrinsic variability of single quartz OSL signals, an electron multiplier charge coupled device (EMCCD) attachment for the Risø reader was used for detecting and imaging luminescence signals. Whilst the EMCCD system currently offers a lower detection sensitivity when compared to the laser system, the ability to use LEDs for stimulation of the OSL signal circumvents the power variability associated with the laser system and allows an investigation of intrinsic variability to be made. In this paper, signal intensity and the composition of components in single grain luminescence signals are considered, and curve deconvolution is undertaken to calculate photo ionisation cross-sections for single grain quartz signals. For the samples considered, intra-sample variability in these characteristics is observed in single grain quartz luminescence signals imaged using an EMCCD. • Single grain quartz luminescence signal properties investigated using EMCCD imaging. • Intra- and inter-sample variability in single grain quartz signals observed. • Correlation between signal intensity and dominance of the fast component not observed. • Photo ionisation cross-section values calculated from single grain quartz OSL signals. [ABSTRACT FROM AUTHOR]

Tephras are significant markers in the stratigraphic record and play a key role in establishing paleoenvironmental and paleoclimate histories worldwide. Despite burgeoning research focused on tephra characterization and correlation techniques, there are still few techniques that allow for the direct dating of tephra, particularly below the lower age limit of K/Ar and Ar/Ar dating methods. In this study, we test different thermoluminescence (TL) dating approaches on the 4–11 μm volcanic glass constituents of three different independently different tephras. By comparing against independent age control, we demonstrate the utility of both blue (320–450 nm) and red (587–651 nm) TL emissions for dating volcanic glasses using single aliquot regenerative (SAR) dose techniques. We find that both blue and red TL emissions from the volcanic glass shards are dim but reproducible and show no evidence for significant sensitivity changes occurring between the natural TL and the first test dose during the SAR protocol. Fading tests on the blue TL signal show that g-values range from 1.6 ± 1.0 to 2.9 ± 1.1%/decade and are statistically indistinguishable with zero at 2σ for the red TL. Bleaching experiments show that both blue and red TL signals are sensitive to light exposure, with sensitivity corrected signals declining by ∼40% over a 2-h period. For all three tephras, both the fading-corrected blue and red SAR-TL ages are consistent with age expectation. These successful results demonstrate the effectiveness of TL techniques for determining the eruption ages of tephra deposits in primary position between ∼1 and at least 30 ka. • Blue and red TL signals are present in volcanic glasses. • Blue and red TL signals from volcanic glass are sensitive to light-exposure. • Both (fading-corrected) blue and red SAR-TL ages are consistent with age expectation. • TL dating of volcanic glass offers a viable direct dating method for use in tephrochronology. [ABSTRACT FROM AUTHOR]

Abstract: Optically Stimulated Luminescence (OSL) and Thermoluminescence (TL) properties of a fluorapatite glass-ceramic have been investigated, with a view to developing a dose assessment technique for medical triage following unplanned exposures of individuals to ionizing radiation. The ceramic is an innovative material used in dental prostheses and restorations. It is strongly sensitive to radiation and the intensity of both the OSL and TL signals are proportional to the absorbed radiation dose. We focused on the optimization of the measuring procedure and investigated characteristics such as reproducibility, fading, minimum detectable dose (MDD), dose response and photon energy response of TL and OSL signals. The dental ceramic exhibited very good reproducibility (<5% at 2σ level) when measured and a linear dose response for a wide range of doses (50 mGy–20 Gy). The MDD values for the samples investigated were ∼5 mGy. The material is not tissue equivalent and the OSL and TL signals are strongly dependent on incident photon energy. Both the luminescence signals exhibited significant fading during the first few hours after irradiation. Its rate was dependent on the parameters of measurement. The results indicate that the material can be used for the purposes of accident dosimetry, however, the fading and photon energy response have to be properly corrected for a reliable dose assessment. [Copyright &y& Elsevier]

Abstract: The shape of infrared stimulated luminescence signals (IRSL) from feldspars has been the subject of numerous studies in the field of luminescence dating. Specifically linearly modulated IRSL signals (LM-IRSL) are commonly assumed to consist of several first order components corresponding to distinct optical stimulation cross sections. This paper models the shape of LM-IRSL signals using a recently proposed kinetic model, which describes localized electronic recombination in donor–acceptor pairs of luminescent materials. Within this model, recombination is assumed to take place via the excited state of the donor, and nearest-neighbor recombinations take place within a random distribution of centers. The model has been used previously successfully to describe both thermally and optically stimulated luminescence (TL, OSL). This paper shows that it is possible to obtain approximate solutions for the distribution of donors in the ground state as a function of two variables, time and the distance between donors and acceptors. Approximate expressions are derived for several possible modes of optical and thermal stimulation, namely TL, OSL, linearly modulated OSL (LM-OSL), LM-IRSL and isothermal TL (ITL). Numerical integration of these expressions over the distance variable yields the distribution of remaining donors at any time t during these experimental situations. Examples are given for the derived distributions of donors in each experimental case, and similarities and differences are pointed out. The paper also demonstrates how LM-IRSL signals in feldspars can be analyzed using the model, and what physical information can be extracted from such experimental data. The equations developed in this paper are tested by fitting successfully a series of experimental LM-IRSL data for Na- and K-feldspar samples available in the literature. Finally, it is shown that the equations derived in this paper are a direct generalization of an equation previously derived for the case of ground state tunneling. [Copyright &y& Elsevier]

Abstract: The dependence of thermoluminescence (TL) of LiF:Mg,Cu,Si on sintering temperatures and dopants concentrations were investigated. The dependency of the TL in LiF:Mg,Cu,Si on sintering temperature exhibits a very sharp maximum at 830 °C. LiF:Mg,Cu,Si is much too sensitive than LiF:Mg,Cu,P to sintering temperature. The glow curve and the TL sensitivity depend on the concentration of Mg, Cu and Si, showing a distinct maximum for certain concentrations of these impurities. Mg seems to be the most essential dopant, as very small changes of the Mg content strongly influence both the glow curve and the TL sensitivity. Si is the main activator responsible for TL emission. The stability to heat treatments in LiF:Mg,Cu,Si was influenced greatly by Mg concentrations. The thermal instability in LiF:Mg,Cu,Si is caused not by Cu and Si but Mg ion state change. It was found that the optimum concentrations are Mg:0.6 mol%, Cu:0.03 mol% and Si:0.9 mol% for this material, which showed the best stability to heat treatment. [Copyright &y& Elsevier]

Abstract: The alkali halide NaCl (Common salt) is an environmentally-abundant phosphor of considerable potential for retrospective dosimetry and radiological event analysis due to its high sensitivity to ionising radiation when analysed by Thermoluminescence (TL), Optically-stimulated luminescence (OSL) or Infrared-stimulated luminescence (IRSL). We report here aspects of luminescence from NaCl relevant to the development of valid protocols for measurement of recent ionising radiation exposure. The timescale of interest in this application is from days to decades, hence our emphasis is on detection and characterisation of TL emission in the 100–300 °C range, and of OSL and IRSL emissions measured following only low temperature preheating (160 °C). A collection of 19 salt samples was assembled, including samples of rock salt and domestic salt produced by evaporation from brine. Analysis of TL emission spectral changes, together with previously reported TL, OSL and IRSL sensitivity changes, confirmed activation of sensitivity change by exposure to temperatures exceeding 160 °C. Kinetic analysis using Chen''s method found E = 0.943 eV and s = 5.1 × 1011 s−1 for the 100 °C TL peak, giving a lifetime at 20 °C consistent with previous calculations and in the range of 7–14 h. [Copyright &y& Elsevier]

Abstract: The effects of prior infrared stimulation on the TL emission of three feldspar minerals (albite, sanidine and orthoclase) were studied. Different reductions in the TL signal were observed in the three samples: albite (Na-rich feldspar) was only partially affected by stimulation while there was an important decrease of TL signal in sanidine and orthoclase (K-rich and intermediate K–Na feldspars). A similar behaviour was also detected when the samples were illuminated at different temperatures. Moreover, when the IR stimulation was performed at temperatures below 100 °C, there was a charge transfer effect (PTTL) that progressively rose, moving from albite to sanidine to orthoclase. A dose recovery experiment was also performed, varying both preheat and measurement temperature. Our results are a further confirmation of the complexity and variability of the luminescence processes in feldspars. They also indicate that the luminescence characteristics of the albite we dealt with are particularly useful for dosimetric application. [Copyright &y& Elsevier]

Abstract: Seventeen domestic and scientific glass specimens were investigated for thermoluminescence (TL) properties suitable for application to retrospective population dosimetry. Usefulness for retrospective dosimetry was initially judged by the presence of well-defined TL glow peaks and the absence of irradiation-independent luminescence. Of particular interest were TL glow peaks having relatively low trap depths, to prevent significant natural dose accumulation. Minimum useful trap lifetimes would be in the order of weeks. Surveys were undertaken to observe the TL and optically stimulated luminescence (OSL) behaviour of each sample. Most samples showed identifiable TL, with Pyrex in particular, and samples from a jar, a lampshade, and opaque blue beads all showing well-defined TL glow peaks with sensitivities that were not significantly affected by prior irradiation and heating of the sample. Kinetic analysis of these samples showed that their TL emission originates from traps with suitable stability for retrospective dosimetry. It is concluded that, while some glass samples show promising results, the inherent variability of an amorphous substance such as glass means that the suitability of each sample must be determined on a case-by-case basis. [Copyright &y& Elsevier]

Abstract: We present investigations of counting statistics for five different luminescence-measuring systems. The dark current background and the counts obtained for a PM tube under constant illumination at various light intensities were measured. Where no divider is present in the counting system, the standard deviation of the number of counts exceeds the value predicted by a Poisson distribution but by different amounts in the different systems. This has implications for analysis of the uncertainties in the estimated equivalent doses and other quantitative analyses of luminescence measurements. We suggest how to account for the observed overdispersion of count numbers in uncertainty estimation. [Copyright &y& Elsevier]

Abstract: The preparation method and some dosimetric properties of the new LiF:Mg,Cu,Si discs are presented. The effect of heat treatments on LiF:Mg,Cu,Si was investigated. The shape of the glow curve for LiF:Mg,Cu,Si is similar to that for standard LiF:Mg,Cu,P (GR-200A), and shows minimal differences when annealed in the range from 260 °C to 290 °C for 10 min. The TL sensitivity for LiF:Mg,Cu,Si is much lower than that for GR-200A, but is 35 times larger than that for TLD-100 and is slightly higher than that for HMCP. The height of the high-temperature peaks for LiF:Mg,Cu,Si is not only lower than that for GR-200A, but also lower than that for HMCP. The glow curve shape of LiF:Mg,Cu,Si annealed at 260 °C for different times shows minimal differences and TL response remains stable. These results indicate that the new LiF:Mg,Cu,Si disc has a good stability to thermal treatments and a lower residual TL signal. [Copyright &y& Elsevier]

Abstract: Non-destructive detection of very low concentrations of 90Sr (about 0.4 Bq g−1) inside powdered samples with masses below 200 mg (such as tooth enamel prepared for EPR measurements) is not a trivial task. Most of the conventional measurement techniques require a special chemical treatment or an enrichment process. Thin-layer α-Al2O3:C passive luminescence beta detectors have been successfully used for measuring dose rates due to beta decay of 90Sr inside small samples. In this paper, a new refinement is introduced for the assessment of 90Sr concentration in dental tissue using thin-layer α-Al2O3:C passive luminescence beta detectors. The performance parameters of passive luminescence beta detection (such as detection and quantification limits) have been evaluated using statistical analysis of the experimental results. The sources of uncertainty have been analyzed and the total uncertainty calculated using Monte Carlo simulations. The results of TL passive beta detection for measurement of 90Sr concentrations are shown to be in good agreement with those obtained using low-level beta counting. [Copyright &y& Elsevier]

Abstract: Thermoluminescence (TL), Optically-Stimulated Luminescence (OSL) and Infrared-Stimulated Luminescence (IRSL) emitted from a set of 19 salt (NaCl) samples were studied for potential application to retrospective dosimetry. TL emission spectra revealed intense TL emissions from most samples, centred on 590 nm; UV and blue emissions were also found. Significant thermally-induced sensitivity changes were observed and TL, OSL and IRSL growth curves were measured. Pulse anneal analysis was performed, as was quantitative imaging of the TL, OSL and IRSL to assess sample heterogeneity. Kinetic analysis found lifetimes at 20 °C of the 200 °C and 240 °C TL peaks to be 0.6 ka and 4 ka respectively; sufficient for application to retrospective dosimetry. [Copyright &y& Elsevier]

Abstract: The thermoluminescence (TL) of porcelain is investigated in order to develop better protocols for retrospective dosimetry. Spatial, spectral and kinetic measurements have been made on several electrical insulators. We broaden our search for suitable techniques by examining the TL emission spectra outside of the blue detection region commonly used by TL readers. The 230 °C TL emission at 620 nm is identified as potentially useful for retrospective dosimetry of radiological events over the past few decades. [Copyright &y& Elsevier]

Abstract: α-Al2O3 single crystals were irradiated to various thermal neutron fluences in the range of 1014 to 1018 n/cm2 with associated fast neutron fluence and gamma rays in the CIRUS reactor. The neutron irradiation of α-Al2O3 crystals in the reactor introduces considerable oxygen vacancies in the crystals, which is confirmed by the presence of F (203 nm) and F+ (225 and 255 nm) bands in their optical absorption (OA) spectra. The concentration of the F and F+ centers increases with the increase in neutron fluence and are responsible for the observed TL and OSL in the α-Al2O3 single crystals. The F/F+ concentration ratio of α-Al2O3 samples irradiated to thermal neutron fluence of 1018 n/cm2 (with an associated fast neutron fluence of 7 × 1015 n/cm2) is 0.68. The photoluminescence and OA studies indicate formation of excess F+ center in the neutron irradiated Al2O3 single crystals. The TL glow curve of the reactor neutron irradiated Al2O3 is different from the TL glow curve structure of the TLD-500 single crystal. [Copyright &y& Elsevier]

Abstract: The Photon Counting Imaging System (PCIS) has been developed to extend the capabilities of traditional luminescence dating technologies by providing a spatially-resolved (imaged) output and a significantly extended spectral range for the detection of luminescence signals, at an overall sensitivity comparable to that of non-imaging luminescence detectors. It is capable of a wide range of both luminescence dating and materials analysis applications, utilising a variety of optical stimulation sources in addition to thermal stimulation, and incorporates easily inter-changeable optical filters for the spectral discrimination of luminescence emissions. [Copyright &y& Elsevier]

Abstract: The LiF:Mg,Cu,Si thermoluminescence materials, recently developed at the laboratory, gain uprising popularity because the materials show several outstanding performance results such as high sensitivities for gamma radiation, flat energy responses with little fluctuation for photons, linear responses over the wide ranges of radiation doses and few residual electrons trapped in the holes. In this study, we investigated the impacts of the Mg concentration and the final thermal treatment conditions on the glow curve structure of LiF:Mg,Cu,Si material to enhance the ratio of high-temperature peak to main peak for the extended application of the two peaks in the high LET radiation dosimetry and in the high-temperature environment. Change in Mg concentration did not affect significantly the ratio of TL responses of high and main dosimetric glow peaks. With Mg concentration in the range from 0.35 to 0.45 mol% and a thermal treatment of 10 min in the range from 400 °C to 440 °C followed by the thermal treatment at 260 °C for 10 min (dual-step thermal treatment) resulted in the highest value of the ratio of TL response of high and main dosimetric glow peaks. [Copyright &y& Elsevier]

Abstract: The use of silicates as thermoluminescent material is well known and ranges from the identification of irradiated food to the dose reconstruction using quartz extracted from bricks and tiles. Recently the possibility to collect silicates from the dust present on personal objects for individual dosimetry in case of radiation accident or radiological attack, was investigated for dose of 10 Gy. The aim of the present work was to investigate the possibility to detect dose levels below 10 Gy. To this extent objects supposed to contain high amount of silicates such as keys, coins and cigarette tobacco () were tested in the dose range 0.1–5.0 Gy. The TL signal was distinguishable from the geological signal in the whole range of dose. To simulate a realistic situation, laboratory irradiation was performed directly on the objects before silicates collection and TL analysis were carried out at two different time points, within a week. The glow curves registered 7 days after laboratory irradiation at 5 Gy showed an artificially radiation-induced TL signal well distinguishable from the natural background. [Copyright &y& Elsevier]

Abstract: Energy-resolved optically stimulated luminescence (OSL) spectra and thermoluminescence (TL) glow curves of a powder sample of YPO4:Ce3+,Sm3+ were measured to investigate the nature of the trapping centre and to locate its energy level relative to the valence and conduction bands of the YPO4 host. The high-temperature glow peak could unequivocally be assigned to Sm2+ (thus Sm3+ acts as an electron trap). The trap depth of this centre, as derived from the OSL excitation spectra, is in good agreement with the Dorenbos model prediction. The OSL excitation spectra also reveal excited states of Sm2+ well below the conduction band. These excited states produce a broadening of the high-temperature TL glow peak and also cause the activation energy determined by the Hoogenstraten method to underestimate the trap depth. [Copyright &y& Elsevier]

Abstract: This review describes 40 years of experience gained at Risø National Laboratory in the development of facilities for irradiation, thermal/optical stimulation and luminescence signal detection. These facilities have mainly been used in luminescence dating and nuclear accident dosimetry. We focus especially on methods for light stimulation and irradiation, and developments of new portable TL/OSL readers for determining doses directly in the field on both Earth and the planet Mars. [Copyright &y& Elsevier]

Abstract: The feasibility of utilizing the pre-dosed OSL signal in the estimation of the equivalent dose has been investigated. The results based on (i) the behavior of growth curve, (ii) dose recovery tests and (iii) non-bleachability of reservoir centres, R-centres, suggests that (i) the pre-dosed OSL does not seem to work satisfactorily in dose estimation unlike the pre-dosed 110°C TL emission and (ii) it may not be applicable in case of bleached specimen. [Copyright &y& Elsevier]

Abstract: It is difficult to relate the IRSL signal from feldspar to a particular region of the TL curve; prior IR stimulation reduces the TL signal over a wide range of temperatures. Such data are apparently consistent with the observation from pulse anneal experiments that a laboratory-induced IRSL signal is detectably eroded by a relatively low temperature preheat. These results can be explained by a distribution of trap depths of IR sensitive traps, and/or by changes in recombination probability induced by IR exposure. To investigate the relative importance of these processes, we first examine the relationship between the loss of blue IRSL and TL signals with preheating, and the effect of prior IRSL on the TL signal. Using IRSL measured at 50°C and a SAR protocol, we then examine the dependence on preheat temperature of equivalent dose (De), laboratory fading rate (g), and the resulting luminescence age, from three sedimentary potassium-rich feldspar extracts. We demonstrate that there is no systematic increase in De for a preheat temperature range from ∼80°C to ∼320°C (60s duration). After fading correction, age plateaus vary slightly over the temperature range examined, but there is no evidence for an increase in age with preheat temperature. We therefore conclude that the main dosimetry trap(s) in feldspar are not significantly eroded by laboratory heating for up to 60s at 320°C, and we tentatively identify the source of this IRSL as a TL peak lying between 410 and 420°C; this suggestion is consistent with a kinetic analysis of sensitivity-corrected IRSL data. The corollary to our observations is that shallow (unstable) traps do not give rise to a significant IRSL signal. [Copyright &y& Elsevier]