Thermoluminescence Of Quartz Research Articles

South American precipitation dipole forced by interhemispheric temperature gradient

Tropical South American hydroclimate sustains the world’s highest biodiversity and hundreds of millions of people. Whitin this region, Amazonia and northeastern Brazil have attracted much attention due to their high biological and social vulnerabilities to climate change (i.e. considered climate change hotspots). Still, their future response to climate change remains uncertain. On precession timescale, it has been suggested that periods of decreased western Amazonian precipitation were accompanied by increased northeastern Brazilian precipitation and vice-versa, setting an east–west tropical South American precipitation dipole. However, the very existence of this precession-driven precipitation dipole remains unsettled given the scarcity of long and appropriate northeastern Brazilian records. Here we show that the precession-driven South American precipitation dipole has persisted over the last 113 ka as revealed by a northern northeastern Brazilian precipitation record obtained from quartz thermoluminescence sensitivity measured in marine sediment cores. Precession-induced austral summer insolation changes drove the precipitation dipole through the interhemispheric temperature gradient control over the regional Walker circulation and the Intertropical Convergence Zone seasonal migration range. Since modern global warming affects the interhemispheric temperature gradient, our study provides insights about possible future tropical South American hydroclimate responses.

Internal Radiation Levels in Natural Quartz Crystals Collected from Southwestern Nigeria; Implications on Thermoluminescence Studies

The relationship between natural thermoluminescence (TL) signal, activity concentrations and the TL sensitivities of twelve (12) quartz samples from different origins were investigated in this study. Gamma spectrometry measurements on the samples were carried out with coaxial-type Germanium detectors (Canberra Industries Inc., Meriden, CT, USA). The TL measurements on the samples were measured using a RISØ TL/OSL reader (model TL/OSL–DA–15). Concentrations of radionuclide activities were only detected in three samples with very low values as compared with world’s average. The highest dose rate in one of the samples was observed to be a factor of 15 lesser than a case of self-dose reported in the literature. The three samples with detectable activity concentrations are the one that possess highest TL signals. All the samples with an exception of one exhibit dependence of sensitization factor of 110 °C TL glow-peak on the equivalent dose (ED). This observation suggested a correlation between the ED of quartz and the sensitization factor of its 110 °C TL peak, an indication of the importance of ED in quartz TL and Optically Stimulated Luminescence (OSL) characteristics. There was no possibility of self-dose effect in all the samples and their radiation safety in exploration and applications in electronics and gemology are validated.

Quartz thermoluminescence spectra in the high-dose range

The red thermoluminescence (RTL) emission of quartz is associated with advantageous features such as high saturation dose and good reproducibility. Previous studies, however, noted inexplicable RTL glow curve shapes with new peaks at large doses (kGy range). Here we present TL spectra of two granitic quartz samples over the additive γ-dose range 0.1–47.9 kGy. While for doses between 0.4 and 1 kGy the TL spectra are dominated by the red emission at 1.95 eV (630 nm), a blue emission at 2.67 eV (465 nm) becomes prominent for higher doses. For one sample, this blue component completely dominates the spectrum for doses > 12.2 kGy with intensity maxima around 200 °C and > 350 °C (heating rate 2 K s−1). The other sample still contains well resolvable red and blue emissions at the largest dose with similar TL peak positions. Signal saturation for the blue emission in the glow curve range 260–300 °C is not yet reached following an additive γ-dose of 47.9 kGy, whereas the red emission generally shows a more subdued signal response for doses > 5–12 kGy. These findings agree qualitatively with additional monochromatic blue and red TL measurements on the same samples. The evolution of supplementary radiofluorescence spectra over the entire γ-dose range is more complex, but suggests that the sensitisation of the blue wavelength region occurs during heating and not during irradiation and through creation of electron traps rather than recombination centres (most likely [AlO4]0 sites). The sharp sensitivity increase at 1 kGy might likewise be related to alkali ion redistribution and/or the removal of non-radiative competitive recombination pathways. While the blue emission still requires thorough investigation, care should be taken when recording RTL using optical filters since significant portions of the registered TL could originate from the blue component entering the RTL transmission window. In practical terms, the dose-dependent change in relative intensities of blue and red TL emissions might help in detecting exposure to high doses.

Defect pair mechanism for quartz intermediate temperature thermoluminescence bands

The well-known 160 °C and 220 °C intermediate temperature bands in quartz thermoluminescence are attributed to the same defect reaction pair proposed previously to explain the 110 °C predose band. In particular, the trend towards longer spectral wavelengths as the glow proceeds across the 110 °C, 160 °C and 220 °C bands is shown to be consistent with the known energy levels of the [AlO4−/h+]0 substitutional defect.

New numerical model for thermal quenching mechanism in quartz based on two-stage thermal stimulation of thermoluminescence model

The effect of thermal quenching plays an important role in the thermoluminescence (TL) of quartz on which many applications of TL are based. The studies of the stability and kinetics of the 325°C thermoluminescence peak in quartz are described by Wintle (1975), which show the occurrence of thermal quenching, the decrease in luminescence efficiency with rise in temperature. The thermal quenching of thermoluminescence in quartz was studied experimentally by several authors. The simulations work presented in the literature is based on the single-stage thermal stimulation model of thermoluminescence, in spite of that the mechanisms of this effect remain incomplete. This paper presents a new numerical model for thermal quenching in quartz, using the previously published two-stage thermal stimulation of thermoluminescence model.

The Chernobyl experience in the area of retrospective dosimetry

The Chernobyl accident, which occurred on 26 April 1986 at a nuclear power plant locatedless than 150 km north of Kiev, was the largest nuclear accident to date. Theunprecedented scale of the accident was determined not only by the amount ofreleased activity, but also by the number of workers and of the general publicinvolved, and therefore exposed to increased doses of ionising radiation. Due to theunexpected and large scale of the accident, dosimetry techniques and practices were farfrom the optimum; personal dosimetry of cleanup workers (liquidators) was notcomplete, and there were no direct measurements of the exposures of membersof the public. As a result, an acute need for retrospective dose assessment wasdictated by radiation protection and research considerations. In response, substantialefforts have been made to reconstruct doses for the main exposed cohorts, using abroad variety of newly developed methods: analytical, biological and physical(electron paramagnetic resonance spectroscopy of teeth, thermoluminescenceof quartz) and modelling. This paper reviews the extensive experience gainedby the National Research Center for Radiation Medicine, Academy of MedicalSciences, Ukraine in the field of retrospective dosimetry of large cohorts of exposedpopulation and professionals. These dose reconstruction projects were implemented, inparticular, in the framework of epidemiological studies, designed to follow-up themedical consequences of the Chernobyl accident and study health effects of ionizingradiation, particularly Ukrainian–American studies of cataracts and leukaemia amongliquidators.

Correlation between thermoluminescence sensitivity and crystallization temperatures of quartz: Potential application in geothermometry

Abstract The thermoluminescence (TL) characteristics of quartz are highly dependent of its thermal history. Based on the enhancement of quartz luminescence occurred after heating, some authors proposed to use quartz TL to recover thermal events that affected quartz crystals. However, little is know about the influence of the temperature of quartz crystallization on its TL characteristics. In the present study, we evaluate the TL sensitivity and dose–response curves of hydrothermal and metamorphic quartz with crystallization temperatures from 209 ± 15 to 633 ± 27 °C determined through fluid inclusion and mineral chemistry analysis. The studied crystals present a cooling thermal history, which allow the acquiring of their natural TL without influence of heating after crystallization. The TL curves of the studied samples present two main components formed by different peaks overlapped around 110 °C and 200–400 °C. The TL sensitivity in the 200–400 °C region increases linearly with the temperature of quartz crystallization. No relationship was observed between temperatures of quartz crystallization and saturation doses (

Determination of trap parameters for thermoluminescence glow peaks of red thermoluminescence of quartz from Japan

Red thermoluminescence in quartz has been generally observed in samples from volcanic deposits or archaeological burnt materials. Red thermoluminescence emission quartz has gained attention as a radiation dosimeter for thermoluminescence dating due to the high-dose saturation level and long-term stability of the thermoluminescence signal. The technique for this application can be improved with an understanding of various trap parameters associated with thermoluminescence glow peaks. The repeated initial rise and computerized glow curve deconvolution methods are used to determine the number of thermoluminescence glow peaks and trap parameters for red thermoluminescence from two types of quartz (Tazawa and Yuda samples) from Japan. For both quartz samples, the glow curves were best described as a superposition of seven glow peaks with activation energies of 0.76–1.95 eV and 0.89–1.91 eV for the Tazawa and Yuda samples, respectively. These results provide useful information for the investigation of the intrinsic characteristics of quartz crystals in the research fields relevant to dating and dosimetry.

Thermoluminescence of Quartz in the Borehole Cores from the Minase Geothermal area, Akita Prefecture, Japan

Thermoluminescence of Quartz in the Borehole Cores from the Minase Geothermal area, Akita Prefecture, Japan

Thermoluminescence of quartz from Shihu gold deposit, western Hebei province, China: some implications for gold exploration

AbstractThermoluminescence (TL) of monomineralic separates have been widely used in various geosciences fields in order to trace the thermal history and aid in prospecting for gold deposits. Quartz is a ubiquitous mineral in the Shihu gold deposit, which is situated in the northern part of the Taihang orogenic belt in the North China craton (NCC). The deposit is hosted by ductile-brittle faults within an Archean metamorphic core complex of the Fuping Group. This deposit is characterized by gold-bearing quartz-polymetallic sulfides and quartz veins. New TL results have been obtained for quartz, in which four type-TL glow curves were identified. The gold-bearing quartz present type III glow curves that consist of two peak glow curves at the middle and high peak temperatures with the similar TL intensity. In addition, the cross-sections of peak temperatures and TL intensity highlight the valuable area where the Au-bearing quartz present weak TL intensity and low-middle peak temperatures. Our results significantly enhance the usefulness of quartz in metallogenic studies of the North China craton and as an indicator mineral in mineral exploration of the Taihang Mountain region.

Quartz Thermoluminescence—Another Potential Paleo‐Thermometer for Studies of Sedimentary Basin Thermal History

AbstractGood reproducibility of quartz thermal stimulated luminescence phenomenon offers the possibility of dating geological events in the subsurface and exploring environmental temperature history. As sandstones in basins generally experienced one certain pattern of thermal history due to effects of temporal and spatial dependent temperature fields, the quartz minerals extracted from these sandstones can be evaluated to explore the thermal regime structure information by thermoluminescence analyzing technique. In terms of equivalence for certain burial depths in the petroleum basin, the mean quantitative temperature field was investigated using both the quartz thermoluminescence apparent age method and laboratory isothermal thermoluminescence simulation measurements. The result shows that the variations of both thermoluminescence glow‐curve pattern and intensity of certain natural thermoluminescence peaks correlate well with the environmental temperature field at corresponding burial depths where the quartz grains were extracted. The quartz natural thermoluminescence glow‐curves peaks shift to high temperature and the thermoluminescence intensity reduction results from the increase of both environmental temperature and burial time for quartz due to deepening burial depth. Both the additive dose thermoluminescence (TL) and isothermal TL (SA‐ITL) techniques were used for quartz mineral TL dating and the resultant apparent ages agree well with each other, and thus one parameter called equivalent temperature was tentatively presented and deducted from apparent TL ages of quartz minerals to evaluate the basin's thermal regime structure. Quartz thermoluminescence signal can be recognized as one potential paleothermometer if the good correlation of calculated equivalent temperature of buried quartz mineral with other paleothermometers can be supported by more lines of future independent geological evidence.

Aberrant thermoluminescence dates obtained from primary volcanic quartz

This study deals with the dating by thermoluminescence (TL) of quartz from six volcanic formations of the Saint Lucia Island (Lesser Antilles Arc). Quartz microcrystals up to one millimetre in size were extracted from dacites and pumice flows and prepared in a way similar to the well-known inclusion technique. The TL properties of these quartz were used to estimate apparent palaeodoses using the multi-aliquot protocol. The quartz TL was studied in three different spectral domains: red, green and ultraviolet/blue. The calculated annual dose-rates yielded a set of 18 age-estimates. For some samples complementary dates were obtained using high temperature TL (HTTL) of plagioclase feldspars. These latter dates combined with previously determined radiocarbon and unspiked K–Ar dates were used to explore the validity of ages computed from the TL of quartz. Individual values for quartz appear to be scattered and do not match ages deduced from 14C, unspiked K–Ar or HTTL on plagioclase dates. These results indicate that when conventional TL methodologies derived from the inclusion method are applied to volcanic quartz major dating problems are to be expected.

The dose dependence and the firing effects on the thermoluminescence of quartz

AbstractPapers on the dose dependence of thermoluminescence of quartz have been published in recent years by research groups from various countries. These papers show that untreated quartz gives very strong superlinearity (up to slopes of 3 in a log‐log scale). Almost all the investigators who describe the above effects refer to a theoretical paper by Kristianpoller et al. (J. Phys. D: Appl. Phys. 7, 1063 (1974) [6]) which shows that adding a competing trap to the energy system of quartz, gives a set of equations which can be solved numerically for various sets of given parameters, when results explain all the above effects. Unlike other investigators who used quartz powders, we preferred to use single crystals of quartz. For better resolution of two or more neighboring thermoluminescence peaks, we reduced the rate of heating in the thermoluminescence measurements to 10 degrees per minute. We found that limiting the temperature in the TL heatings during the set of doses to 400‐450 K, gave extremely high superlinearity (slopes close to 7). A set of decreasing doses was found to reduce the high superlinearity and to increase the 430 K peak by more than 3 orders of magnitude without any firing. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Isothermal thermoluminescence signals from quartz

Dating sediment older than ∼ 150 ka still remains difficult because of a lack of suitable chronological tools. Here we report on studies to determine whether measurements of quartz thermoluminescence made at constant temperature (isothermal luminescence) can be used to extend the dose limit in sediment dating. The origins and dosimetric characteristics of the quartz isothermal signal at 310 ∘ C are investigated. It is shown that, in general, application of a single aliquot regenerative (SAR) dose protocol with this signal overestimates the expected equivalent doses in sedimentary samples, from a variety of environments and locations. This anomaly originates from a change of luminescence sensitivity, during or after the initial thermal measurement. A single aliquot regenerated and added dose (SARA) protocol suggested as the only approach known to compensate for this initial change of sensitivity was unsuccessful.

Finding model parameters: Genetic algorithms and the numerical modelling of quartz luminescence

The paper presents an application of genetic algorithms (GAs) to the problem of finding appropriate parameter values for the numerical simulation of quartz thermoluminescence (TL). We show that with the use of GAs it is possible to achieve a very good match between simulated and experimentally measured characteristics of quartz, for example the thermal activation characteristics of fired quartz. The rate equations of charge transport in the numerical model of luminescence in quartz contain a large number of parameters (trap depths, frequency factors, populations, charge capture probabilities, optical detrapping probabilities, and recombination probabilities). Given that comprehensive models consist of over 10 traps, finding model parameters proves a very difficult task. Manual parameter changes are very time consuming and allow only a limited degree of accuracy. GAs provide a semi-automatic way of finding appropriate parameters.

Estimation of equivalent dose using quartz isothermal TL and the SAR procedure

Optically stimulated luminescence (OSL) from quartz is now widely applied to the dating of Quaternary sediments. Unfortunately, quartz OSL ages are often limited to 100–200 ka by the saturation level of the dose–response curve (∼300 Gy), unless the annual dose from the surrounding sediments is sufficiently low. Quartz thermoluminescence (TL) has been used in the past to date beyond this range, but this signal is no longer widely employed because of the poor reproducibility obtained from multiple-aliquot procedures, and because of the greater uncertainty in the degree of bleaching compared to the OSL signal. Here we investigate, for the first time, the possibility of using the quartz isothermal thermoluminescence (ITL) signal at 310 °C for dating sediments from various depositional environments. The single-aliquot regenerative-dose (SAR) procedure is shown to be applicable to this signal, and a protocol is developed. Dose recovery tests are used to examine the reliability of the new protocol for equivalent dose ( D e) estimation using quartz ITL. The D e values obtained using the new protocol are compared to those from conventional SAR OSL. We estimate D e values as high as 550±50 Gy, corresponding to a luminescence age of 147±13 ka, for a natural loess sample from Korea. Our results suggest that quartz ITL shows potential for dating samples well beyond the OSL age range. The new ITL SAR protocol has several advantages common to all applications of the SAR procedure: D e estimation from a single aliquot using interpolation, excellent reproducibility, high throughput (allowing routine testing of protocol performance), and the ability to examine the distribution of D e within a sample.

Thermoluminescence parameters and kinetics of irradiated inorganic dust collected from black peppers

Irradiated foods can be detected by thermoluminescence (TL) of contaminating inorganic dust particles. In this study, black peppers were irradiated with gamma rays at doses of 1, 3, 5 and 10 kGy. The inorganic dust particles collected from irradiated black pepper are investigated. This study reports the mineral composition of this dust being, mainly quartz, feldspar and little amount clay minerals. The TL detection method is clearly able to distinguish irradiated and non-irradiated black peppers at the doses ranging from 1 to 10 kGy. The paper provides a detailed calculation of the activation energy ( E), frequency factor ( s) and the order of kinetics of the 240 °C TL identification peak in polymineral dust material. The experimental and computerized deconvolution results are consistent with the presence of a closely overlapping second-order TL peaks in the identification peak at 240 °C. The TL kinetic parameters of overlapping peaks were estimated by computerized deconvolution method. The computer deconvolution shows the existence of four well-defined TL peaks at 118, 210, 270 and 305 °C. These four peaks probably due to the combined TL of quartz and feldspar minerals.

Isothermal decay studies of intermediate energy levels in quartz.

The recent interest in the thermoluminescence of quartz extracted from unfired building materials, such as mortar and concrete for dose reconstruction applications, led to the requirement of an accurate determination of the lifetime of the intermediate glow peaks in this mineral. The prediction of the lifetimes of these peaks is helpful in establishing the likely time range within which retrospective measurements can be carried out. These peaks, corresponding to intermediate energy levels, occur in the glow curve in the temperature range 150-250 degrees C (heating rate 2 degrees C/s). Lifetimes of 720+/-70 days and 580+/-70 years (at a temperature of 15 degrees C) were derived for the two main peaks placed in the glow curve at approximately 150 degrees C and 200 degrees C, respectively, using the isothermal decay technique. These results as well as the estimated values of the trap parameters (thermal activation energy and frequency factor) have been compared with the data already available in the literature.

Modelling thermal activation characteristics of the sensitization of thermoluminescence in quartz

The sensitization of the ∼110°C thermoluminescence peak in quartz, also termed the ‘pre-dose’ effect, was previously explained using an energy level model including two electron trapping states and two hole centres. The experimental procedure includes a stage of high temperature activation following a relatively large irradiation of the sample. The response to a small test-dose was found to depend on this activation temperature. With different quartz samples, different behaviours of the thermal activation characteristics (TACs) were found. In typical TACs, the sensitivity reached a maximum at ∼500°C, followed by a rather sharp decline in some samples; in others a maximum was reached at ∼350°C followed by a slight decline towards a plateau level. In this work, we show that these behaviours can rather easily be explained within the framework of the two traps–two centres model. This is done by numerical solution of the relevant sets of differential equations governing the different stages of the experimental procedure. The different kinds of dependence were simulated with different sets of trapping parameters. A better insight into the processes taking place is reached, which may have implications in the application of pre-dose dating of archaeological quartz samples and in retrospective dosimetry.

Measuring the external exposure dose in the contaminated area near the Chernobyl nuclear power station using the thermoluminescence of quartz in bricks.

We collected bricks from buildings in the heavily contaminated evacuated area of Belarus in a 30-km zone around the Chernobyl nuclear power station and the Gomel-Bryansk area of 150-250 km from Chernobyl and estimated the cumulative radiation dose caused by the reactor accident by measuring the thermoluminescence (TL) of the bricks. The annual dose at each location was measured using glass dosimeters and thermoluminescence dosimeters (TLD). The dose rate was measured using an energy-compensated NaI scintillation survey meter. The soil contamination near the location of each brick was measured using a germanium semiconductor detector. The main purpose of the project was to extrapolate the relation between the cumulative external dose and the present dose rate or contamination level to the lower contaminated areas. The results of the glass dosimeter, TLD, and survey meter determinations were almost identical. For a determination of the annual dose higher than 10 mGy y(-1), the cumulative dose by TL (TL dose) was roughly proportional to the annual dose and about 1.5 times larger than the cumulative dose calculated from the annual dose and 137Cs half life. The difference is expected due to the contribution of short-lived nuclides immediately after the accident or localized heavy contamination of the ground surface with 137Cs that migrated afterwards. For annual dose smaller than 10 mGy y(-1), the proportionality was not observed and most of the locations facing indoors showed TL doses very much larger than that expected from the proportionality. The cumulative dose outdoors by TL was also roughly proportional to the regional 137Cs contamination level and the proportional constant is about 10(-1) mGy per GBq km(-2), and is about 250 times larger than the present annual internal dose derived from published results. The correlation between the present dose rate where the brick was sampled and the average 137Cs concentration in the ground soil near the point is not clear, possibly because of the large spatial fluctuation in the 137Cs concentration in the soil.