Hüseyin Toktamiş

Thermoluminescence glow curve analysis of natural onyx from Turkey.

In this study, the thermoluminesce (TL) properties of natural onyx were determined after β-irradiation ((90)Sr/(90)Y) at room temperature. The effect of the additive dose and variable heating rate for TL glow peaks of the sample were investigated. Computerized glow curve deconvolution (CGCD) methods were used to determine the number of peaks and kinetic parameters related to the TL glow peaks in natural onyx from Turkey. It was also determined kinetic parameters of onyx by means of the variable heating rate (VHR) method. The sample was exposed to β-irradiation between 2.4 Gy and 2.457 kGy. The CGCD methods showed that the glow curve of sample is the superposition of at least six first order components which were ascribed as P1-P6. The dose responses of some peaks have similar patterns and they follow linearity. The effect of heating rates on the response of dosimetric glow peaks of sample was studied. The maximum TL peak intensities of glow curve are decreasing with increasing heating rate and maximum TL peak intensities at 1 °C/s drops to 20% of the initial value when the sample is read at 6 °C/s.

Effects of Annealing on Thermoluminescence Peak Positions and Trap Depths of Synthetic and Natural Quartz by Means of the Various Heating Rate Method

Some environmental and experimental variables such as annealing process alter the structure of glow curves of some thermoluminescence materials. We investigate the effects of annnealing on thermoluminescence peaks of synthetic and natural quartz at different heating rates. The experimental results show that the peak temperatures of glow peaks in annealed samples shift to higher temperature sides. The amount of shifting is higher for low temperature peaks than high temperature peaks. The trap depths of annealed and unannealed samples of both synthetic and natural quartz are also obtained by various heating rate methods. It is noted that the annealing process affects the trap depth of all glow peaks and the trap depth increases after the annealing process.

Thermoluminescent dosimetric characteristics of annealed quartz

In the given present study, the effect of pre-irradiation heat treatment at 500 and 600 °C on the glow peaks of synthetic quartz was examined as a function of annealing time to obtain an optimum annealing procedure. It was observed that the annealing time is not a strongly sensitive parameter to change the intensities of glow peaks. On the other hand, the intensities of glow peaks between room temperature (RT) and 200 °C were continuously increased during successive readings after heat treatments. Moreover, the intensities of glow peaks above 250 °C have good stabilities. The obtained repeatability of a glow peak at ∼320 °C over 10 cycles is within 5% after the application of annealing at 600 °C for 1 h. The general thermoluminescent dosimetric characteristics of synthetic quartz, such as the dose–response, signal fading as a function of storage time, and reusability were also tested using the annealing condition at 600 °C for 1 h. It was observed that dose-response behaviours of all glow peaks are similar to each other. They first follow linear part and then saturated at different dose levels. Peak 1 completely disappeared after 1 month storage in the dark room at RT. On the other hand, the intensity of peaks 2+3 was approximately reduced to 15% of its original value whereas the other peaks (P4–P5) were not sufficiently affected during this period.

Thermoluminescence behavior of basaltic rocks collected in southeastern region of Turkey

Basalt is well known as an extrusive igneous rock erupts on land by volcanic eruption. It is darker, denser and finer grained compared to the familiar granite of the continents. The study reveals the thermoluminescence properties (TL) of basaltic rocks which collected in southeastern region of Turkey. With this study, the variations of glow curve of the basalt at the different grain sizes, different annealing temperature and different annealing time have been investigated. This study also includes, dose response and heating rate experiments. As a result, the basalt sample shows thermoluminescence properties with a wide peak about 200°C. The best TL sensitivity was observed at samples whose grain size is ~100µm. The basalt sample has a wide TL glow curve. A linearity for the values up to 155Gy and supralinearity between 155Gy and 615Gy in dose response are observed and it reaches to saturation beyond 615Gy. Thermal treatments at higher temperatures decrease the TL sensitivity.

The effects of thermal treatments on the thermoluminescence properties of biogenic minerals present in the seashells

ABSTRACT In this study, thermoluminescence (TL) properties of the biogenic minerals present in the seashell samples at different temperatures and annealing times have been studied. Three explicit peaks are seen in the glow curves roughly at 100°C, 180°C, and 380°C. One of the prominent results is that annealing above 600°C affects enormously the TL intensity, whereas no remarkable TL intensity is observed for unannealed samples. The highest intensity and area under the curve were observed at 700°C annealing temperature, and 180 minutes annealing time and 1500 times bigger than the unannealed samples. A linear dose response is observed between 2.4 and 72 Gy and beyond this value, a sublinear relation is observed. Unfortunately, a huge decrease in TL intensity is observed about 51% of its initial value, after 5 hours of storage time.