• Nuclear Engineering and Technology
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• v.29 no.5
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• pp.385-392
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• 1997

The shape of TL glow curve is a useful indicator for assurance of correct reading of the personal dosimeter. Since the reading procedure of TLD is irreversible, however, an analytic remedy should be considered to procure reliable dosimetric information for the readings with irregular glow con shape. In this study, kinetic trapping parameters of CaSO$_4$ : Dy Teflon personal dosimeter(Teledyne PB-6A) were analyzed by Halperin and Braner's model for general-order kinetics. From these kinetic tapping parameters, we also developed a simple procedure to retrieve the dosimetric information from abnormally distorted glow curves. The computerized glow curve deconvolution(CGCD) fitting of the reference glow curve with kinetic parameters from this study yields relative errors of about 5% from the expected integral. It was also found that the glow curve remedial procedure developed could retrieve the distorted TL glow curves within ewer ranges of 1575. With the glow curve retrieval techniques, doses incurred by gamma radiation can now be successfully re-constructed for the CaSO$_4$ : Dy Teflon dosimeter resulting abnormal glow curves.

• Progress in Medical Physics
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• v.4 no.2
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• pp.49-58
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• 1993

The complex glow curves were split into isolated glow curves to be calculated the values of kinetic order, activation energy, escape frequency and density of initial trap from the independent glow curves using the mathematical method of thermally stimulated processes. The minimization of the intensity difference between measured and theoretical glow curve was done by the nonlinear least-square program. The results of the fitted curves were almost equal to the actual values of the parameters. Thermoluminescence from gamma ray irradiated ${\alpha}$-Al$_2$ $O_3$ over the range of 300K to 600K was split into six glow curves. The kinetic order, activation energy and escape frequency of first glow curve were obtained as 1, 1.12eV and 6.79X10$\^$12/sec$\^$-1/, respectively, which were similar to the results of other method. Also the parameters of the second and the third glow curve and so forth were calculated.

• Preventive Nutrition and Food Science
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• v.7 no.2
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• pp.188-194
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• 2002

This study was carried out to observe changes in several detection factors derived from thermoluminescence (TL) of minerals separated from irradiated Korean perilla and sesame seeds during storage under normal room and darkroom conditions. The TL intensities of the first glow curves increased from 0 to 5 kGy but only slightly increase from 5 to 10 kGy. Maximum TL temperatures of the first glow curves in all irradiated samples were around 20$0^{\circ}C$, ranging from 150 to 25$0^{\circ}C$. Since the control (0 day of storage) glow curve ratios of G3 and G4, calculated from re-irradiated (1 kGy) sample were over 0.5, detection of irradiation was possible. However, because Gl ratios were below 0.1, they were classified as non-irradiated. There was n unique first glow curve shape that could be clearly seen in all irradiated samples, regardless of storage conditions, that was never seen in non-irradiated samples. In all samples, the maximum TL temperatures and shape of the second glow curve was in a lower temperature range than that of the first glow curve. Therefore, detection of irradiated Korean perilla and sesame seeds was possible fur up to 3 months after irradiation, regardless of storage conditions, by examining several TL detection factors; including TL intensity, glow curve ratios maximum TL temperatures, and the shapes of glow curves.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.1
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• pp.149-153
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• 2001

Three-dimensional thermoluminescence(TL) spectra of LiF: Mg, Cu, Na, Si TL material based on temperature, wavelength and intensity were measured and analyzed. The glow curves were obtained by integration of luminescence intensity for wavelength at each temperature, and various trapping parameters related to the trap formation were determined by analyzing these curves. Computerized glow curve deconvolution(CGCD) method which based on general order kinetics(GOK) model were used for the glow curve analysis. The glow curves of LiF:Mg, Cu, Na, Si TL material were deconvoluted to six isolated glow curves which have peak temperature at 333 K, 374 K, 426 K, 466 K, 483 K and 516 K, respectively. The 466 K main glow peak had an activation energy of 2.06 eV and a kinetic order of 1.05. This TL material was also found to have three recombination centers, 1.80 eV, 2.88 eV and 3.27 eV by TL spectra analysis based on Franck-Condon model. It showed that 2.88 eV is the dominant center, followed by 3.27 eV level, and 1.80 eV center is ascertained as emission center of this material even though its very weak emission intensity.

• Preventive Nutrition and Food Science
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• v.5 no.3
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• pp.142-147
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• 2000

To establish a detection method of irradiated perilla and sesame seeds, studies were performed with pulsed photostimulated luminescence (PPSL) and thermoluminescence (TL). The PPSL photon counts of the mineral separated from irradiated sesame and perilla seeds were higher than unirradiated one and exhibited an increase with increasing irradiation dose and mineral content. Also TL intensities of minerals separated from irradiated sesame and perilla seeds increased with increasing irradiation dose. In all samples, detection was possible with shapes and maximum TL temperatures of the second glow curves showing lower regions than those of the first glow curves and correctly classified as irradiated samples. Glow curve ratios of irradiated samples were higher than 0.5. These results suggest that PPSL and TL are applicable methods for the detection of irradiated perilla and sesame seeds.

• Preventive Nutrition and Food Science
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• v.6 no.1
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• pp.23-28
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• 2001

A study was carried out to establish a detection method of irradiated shellfish through thermoluminescence (TL). The TL intensity of first glow curves for irradiated bloody, freshwater, and short-neck shellfish increased from control until 5 kGy and increased slightly room 5 kGy until 10 kGy. Maximum TL temperatures of all irradiated samples tested were below 23$0^{\circ}C$, within temperature interval of 150~25$0^{\circ}C$ recommended for evaluation. Since just in control, glow curve ratios of G3 and G4 calculated from re-irradiated (1 kGy) bloody, freshwater and shortneck were over 0.5, detection in control was possible. However, as glow curve ratios after three months were below 0.5, detection by glow curve ratios after three months was impossible. Gl, which calculated from unirradiated samples, exhibited below 0.1, they were classified as unirradiated. In all samples, all the irradiated shellfish could be classified correctly as irradiated by hemaximum TL temperatures and shape of the second glow curve because those were shown in a lower temperature region than those of the first glow curve.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.1
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• pp.8-13
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• 1990

The microscopic relaxation parameters for the single crystal were measured by using thermally stimulated depolarization (TSD). Initial rise method, various heating rate method and total glow peak method were used for the determination of the activation energy and Debye relaxation time from TSD glow curves. Activation energy, pre-exponential factor and relaxation time for impurity-vacancy dipole reorientation were 0.55eV, 1.97$\times$10 super(-12) sec and 12.19sec in average, respectively. Dielectric dissipation factor for the crystal was calculated from the measured TSD glow curve, its value being about 3$\times$10 super(-2).

• Preventive Nutrition and Food Science
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• v.10 no.1
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• pp.17-21
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• 2005

This study was carried out to determine whether detection of minerals separated from irradiated mussel could be could be done by thermoluminescence (TL) method. After the minerals were separated by sodium polytungstate solution (2.0 g/mL) from irradiated mussel, organic compounds remaining in the minerals were removed by acid-base treatment and dried at 50℃ overnight, and then the minerals were measured through TL. The TL intensities of separated minerals at different irradiation doses during storage conditions of room and darkroom were obtained. TL intensity of first glow curves for minerals separated from irradiated mussel showed linear increase from the control to 5 kGy and slight increase from 5 kGy to 10 kGy. Since glow curve ratios of G2, G3 and G4, calculated from re-irradiated minerals measured immediately after irradiation and after storage of three months were over 0.5, detection of irradiation was possible. G1, which showed the glow curve ratios above 0.1, was classified as non-irradiated samples because the unique first glow curve was not found within the recommended temperature interval (150-230℃). Hence, on the basis of TL intensity, and glow curve ratio and shape, it is possible to correctly identify irradaited mussels after mineral separation during storage.

• Korean Journal of Food Science and Technology
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• v.32 no.3
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• pp.525-530
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• 2000

A study was carried out to establish the detection method of irradiated agricultural products cultivated in Korea by Thermoluminscece(TL). Samples were irradiated using Co-60 gamma rays at various doses(0.05, 0.1, 0.2, 0.3 and 0.5 kGy). After irradiation, separated minerals of the samples measured by TL. TL intensity increased with increasing doses and the irradiated samples were higher than the non-irradiated samples. TL first and second glow curves showed maximum TL temperature point at $176.16{\sim}190.08^{\circ}C$ and $143.84{\sim}146.56^{\circ}C$, respectively. All the irradiated samples can be classified correctly by the shape of the glow curve and the glow curve ratio. Correlation coefficients of ginger, carrot, potato and sweet potato were 0.9968, 0.8522, 0.9612 and 0.9071, respectively, that showed very high correlation between irradiation dose and TL intensity. Therefore, these results suggest that TL measurement is an useful detection method for irradiated agricultural products.

• Journal of Ginseng Research
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• v.37 no.4
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• pp.483-490
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• 2013

Gamma-irradiation (0-7 kGy) of ginseng is permitted in Korea for the purpose of microbial decontamination; with strict labeling, traceability and monitoring requirements. An identification study was conducted to determine the photostimulated-luminescence (PSL) and thermoluminescence (TL) properties of gamma-irradiated fresh and white ginsengs cultivated in different areas. Dose- dependent PSL-based screening was possible for white ginseng samples; however, inappropriate results from non-irradiated fresh ginseng samples were obtained, showing intermediate (700 to 5,000) or positive ($T_2$ >5,000, irradiated) PSL counts due to the abundance of minerals on the surfaces of the samples. TL analysis of separated minerals from all non-irradiated samples gave TL glow curves of low intensity with a maximum peak after $300^{\circ}C$. However, well-defined irradiation-specific (high intensity with a maximum peak at about $200^{\circ}C$) glow curves were observed for all the irradiated samples, regardless of their type and origins. TL ratios (first glow curve /second glow curve) were also determined to confirm the irradiated (>0.1) and non-irradiated (<0.1) results. SEM-EDX (scanning electron microscope-energy dispersive X-ray) and XRD (X-ray diffraction) spectroscopic analyses showed that feldspar and quartz minerals were the main source for the typical radiation-specific luminescence properties.