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[en] Optically stimulated luminescence (OSL) and pulsed OSL have been utilized broadly for luminescence dosimetry as well as archaelogical and geological dating. It has been pointed out that in many cases, the decay of the OSL during continuous stimulating light (cw-OSL) and that of pulsed OSL following a pulse of stimulating light, do not generally behave according to a simple exponential function. In the present work, it is shown by the use of numerical simulation, that with the simplest model of a single trapping state and a single kind of recombination center, a decay curve significantly slower than a 'normal' exponential can emerge. These results could be fitted to a stretched-exponential law, exp[-(t/τ)β] with 0<β<1 with surprisingly good agreement for the decay of OSL following a stimulating light pulse. As for the decay of OSL during the exposure to stimulating light, a typical behavior found in the simulation is an initial nearly exponential decay, followed by stretched-exponential decay at longer times. In particular, the cases where β is significantly smaller than unity (e.g., β∼0.5) are of interest. It is to be pointed out that several relaxation phenomena in complex condensed-matter systems have been found to follow the mentioned stretched-exponential decay law. This includes some reports in the literature of stretched-exponential decay of luminescence, usually in the very short time range. It has been suggested, however, that this behavior is always associated with some kind of disorder in the sample, e.g. the disorder occurring in porous silicon. The main new points in the present work are that this kind of relaxation can be expected to occur in the two kinds of OSL mentioned above and that they result from a single crystal with only one trapping state and one kind of recombination center. The concept of half-life of the decay in these cases is considered in view of the present results
[en] This paper examines the effects of optically stimulated luminescence (OSL) components, other than that usually termed the fast component, on dose determination by the single-aliquot regenerative-dose (SAR) protocol. Results are presented for 'dose recovery tests', in which a known laboratory dose, delivered after optical bleaching at room temperature, is measured using the SAR protocol. Data obtained using either the initial OSL signal or the fast component, derived by curve fitting, are compared. Dose recovery tests are also carried out when an additional step is added to the SAR protocol, aimed at reducing recuperation, i.e. the residual signal observed in a SAR cycle when no regenerative dose is applied. The results for quartz from various sources indicate much improved dose recovery when only a well-separated fast component is analysed
[en] Radiation scattered throughout the room during fluoroscopy-guided interventional (FGI) procedures was quantified at different locations using nanoDot optically stimulated luminescence dosemeters. All the tube angulation imaging shows that the radiation spectrum resembled a single peak distribution. The left anterior oblique 90 deg. C shows the highest single peak distribution (28.65 mSv/h). The single peak distribution for standard anteroposterior, left anterior oblique 45 deg. C and right anterior oblique 45 deg. C imaging was 13.32, 22.99 and 17.40 mSv/h, respectively. All tube angulation shows that the position of the interventional radiologist experienced a higher radiation level compared to other staffs. The doses of radiation varied widely around the perimeter of the patient's table and changed in accordance to imaging angles during procedures. Knowledge pertaining to radiation exposure levels is integral in order to avoid adverse risks, particularly among staff. (authors)
[en] Bleaching spectra of the 'fast' and 'medium' optically stimulated luminescence (OSL) components of quartz are reported. A dependence of photoionization cross-section, σ, on wavelength was observed for the ast and medium components and a significant difference in their responses to stimulation wavelength was found. The ratio of the fast and medium photoionization cross-sections, σfast/σmedium, varied rom 30.6 when stimulated with 590 nm light to 1.4 at 375 nm. At 830 nm the ast and medium photoionization cross-sections were found to be sufficiently different that infrared bleaching at raised temperatures allowed the elective removal of the fast component with negligible depletion of the medium. A method for optically separating the OSL components of quartz is suggested, based on the wavelength dependence of photoionization ross-sections
[en] Nano composites based on ultrahigh molecular weight polyethylene UHMWPE and Cd0,5Zn0,5S were obtained with a component of 60/40 vol.% and dispersion of sulfides 80-100 nm. A comparative analysis of the photo -and radio thermoluminescence spectra with UV and / or γ-rays at 77 K was carried out, the values of T were determined, and the structural transitions were compared. The temperature dependences of the dielectric constant εk and dielectric loss tgδ (T) are obtained.
[en] In luminescence measurements of potassium-feldspar (K-feldspar), both infrared (IR) and blue light (BL) can be used as stimulation sources. Component analysis suggests that the blue light stimulated luminescence (BLSL) measured at 60 °C from K-feldspar can be fitted using three components, namely fast, medium and slow. In order to explore the relationship between the origin of the infrared stimulated luminescence (IRSL) signal and the different components of the BLSL, five sets of experiments were conducted, namely post-IR BLSL (pIR-BLSL), post-BL IRSL (pBL-IRSL), pulse annealing tests, dose response and laboratory fading rate tests. It is observed that most of the IRSL signal can be bleached by BL, while the BLSL signal can only be partially bleached by the IR. The sources for IRSL are mainly associated with the fast and medium components of the BLSL signal.
[en] A series of OSL properties of fragments from split feldspar grains have been investigated. These are (1) the response to a radiation dose, (2) the recycling of corrected induced luminescence (Li/Ti), (3) the corrected natural luminescence (LN/TN), (4) the corrected thermal transfer luminescence (termed herein Ltt/Ttt) and, (5) the rate of anomalous fading ('g'). It was found that the parameters of different parts of the same grain are the same. The relative uncertainty, at the 2 sigma level, at which we can claim that the measured parameters are correlated, is generally less than 5% but is ca 40% for the anomalous fading rate due to measurement uncertainty. For young partially bleached sediments, the result is that one could use one fragment to evaluate the equivalent dose and another to assess the contribution of thermal transfer resulting from preheating the natural luminescence
[en] In the past decade, as problems in luminescence dating have been encountered and addressed, the once simple and standard methods for measurement have been replaced with a myriad of variations, often ad hoc. As a consequence, it has become more difficult and time consuming to program the data taking, and to manage the resulting data. As methods change, new instrumentation often must be integrated into the measurement systems, usually with difficulty. We have implemented a number of approaches for improving this situation such as devising a simple but versatile scripting language for data acquisition, a means of handling arbitrary data formats, and a new modular architecture for luminescence instrumentation. The Daybreak 2AP/1 TL/OSL reader is described as an example using this architecture. We will also suggest a number of avenues that will lead to further improvements in data handling, archiving, and inter-laboratory data transfer
[en] The optically stimulated luminescence (OSL) from quartz is known to be the sum of several components with different rates of charge loss, originating from different trap types. The OSL components are clearly distinguished using the linear modulation (LM OSL) technique. A variety of pre-treatment and measurement conditions have been used on sedimentary samples in conjunction with linearly modulated optical stimulation to study in detail the behaviour of the OSL components of quartz. Single aliquots of different quartz samples have been found to contain typically five or six common LM OSL components when stimulated at 470 nm. The components have been parameterised in terms of thermal stability (i.e. E and s), photoionisation cross-section energy dependence and dose response. The results of studies concerning applications of component-resolved LM OSL measurements on quartz are also presented. These include the detection of partial bleaching in young samples, use of 'stepped wavelength' stimulation to observe OSL from single components and attempts to extend the age range of quartz OSL dating
[en] The sensitivity change of the blue-light stimulated luminescence (BSL), red thermoluminescence (RTL) and blue TL (BTL) signal with annealing treatment was investigated on several RTL-quartz samples. The BSL-signal from volcanic quartz was recognized to offer extremely weak emission in comparison with the one from archaeological burnt quartz. It was found that the BSL-sensitivity of the volcanic quartz was remarkably enhanced by up to a factor of 40 after annealing treatment, in comparison with the slight enhancement of 2.4 for archaeological burnt quartz, accompanied with a slight decrease of RTL-sensitivity. As a result, the archaeological burnt quartz has been verified to be datable using both BSL and RTL measurements, while RTL dating was recommendable from old age samples of volcanic origins