In order to compare the dosimetric properties of two kinds of solid state detectors used for monitoring ex- ternal exposures,experiments were performed for the GD-300 series of radiophotoluminescent glass detectors (R...In order to compare the dosimetric properties of two kinds of solid state detectors used for monitoring ex- ternal exposures,experiments were performed for the GD-300 series of radiophotoluminescent glass detectors (RPLGD)and the GR-200 series of thermoluminescent detectors(TLD).X-rays and ^(137)Cs and ^(60)Coγ-rays were used to irradiate the RPLGDs and TLDs,their dose linearity,uniformity/reproducibility of signal,fading effect and energy dependence were compared.Both kinds of the detectors have generally good dosimetric properties.The dose linearity and energy dependence of the GD-351 dosimeters and the TLDs are nearly the same,but the RPLGD is much better than the TLD in terms of the uniformity and fading effect.展开更多
In the fine-grain TL dating the full o dose must be converted into the equivalent P dose. The conversion is finished by Keff-value, which is an effective or effectiveness. But the Keff can not be measured directly for...In the fine-grain TL dating the full o dose must be converted into the equivalent P dose. The conversion is finished by Keff-value, which is an effective or effectiveness. But the Keff can not be measured directly for each sample and only the external radiative efficiency K3.7 can be measured. In order to obtain the Keff a special study for the conversion factor of Keff to K3.t has been made using the ultrathin TLD. The results show that the conversion factor of tile TLD for archaeological samples is 0.847, which is in agreement with calculated value 0.85.展开更多
Pulsed photo-stimulated luminescence (PPSL) is a simple screening method that can be employed qualitatively at the spot for the detection of eggs treated with ionizing radiation.Due to the variations in the results du...Pulsed photo-stimulated luminescence (PPSL) is a simple screening method that can be employed qualitatively at the spot for the detection of eggs treated with ionizing radiation.Due to the variations in the results during storage,the eggs of ostrich,duck,hen,and quail were irradiated to doses of 0,1,2,and 3 kGy.Most of the samples were incorrectly identified during storage after four months of irradiation.Thermoluminescence (TL) technique was also tried by using egg shells in order to confirm the irradiation treatment in eggs.TL glow curves were recorded between the temperatures 50℃to 400℃at the rate of 5°/s for all the control and irradiated samples.On the basis of integrated areas of first glow curves (TL1),the glow curve ratios (TL1/TL2) and the shapes of maxima of TL1, the irradiation treatment of all the eggs was confirmed.Furthermore,the presence of calcite and aragonite minerals that cause the TL signal in the egg shells were studied using X-ray diffraction spectrometry.展开更多
Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food.Because of the rapid commercialization of irradiated foods throughout the...Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food.Because of the rapid commercialization of irradiated foods throughout the world,compliance of different regulations relating to use of technology in different countries and demand of consum- ers for clear labelling of irradiated foods,there is need for the development of analytical methods to detect radiation treatment of food.Among several methods studied so far,thermoluminescence (TL) is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles.In this study,the irradiated and unirradiated wheat and rice samples were analyzed using the TL method.The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture (NIFA),Peshawar.The mineral contaminants were isolated by jet water,ultrasonic treatment,and density gradient.TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50—500℃using a TL reader.Generally,the glow curves for irradiated samples showed much higher TL intensities (TL_1) than the unirradiated samples.The results were normalized by re-irradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves (TL_2).The ratio of the area of first glow curve to that of second glow curve (TL_1/TL_2) was calcu- lated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples.Finally,the shapes of the glow curves for irradiated and unirradiated samples were also analyzed.On the ba- sis of these results (comparison of TL-intensities,TL_1/TL_2 ratios and shapes of the glow curves),all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.展开更多
In routine thermoluminescence(TL) dating,there is often a tendency to omit an absolute determination of the thorium and uranium content in the sample and simply measure the total alpha count rate.The annual dose is th...In routine thermoluminescence(TL) dating,there is often a tendency to omit an absolute determination of the thorium and uranium content in the sample and simply measure the total alpha count rate.The annual dose is then calculated assuming equal activities for a Th/U weight ratio of about 3.17. In fact this ratio is varied significantly in pottery.Calculation of the annual dose conversion factors from data using the total alpha count rate in a selected range of Th/U weight ratios shows significant differences.The results indicate that the additional error contribution to the final TL age is in the range ±2.5%to±4.1% for most cases where the Th/U ratio lies between 1.1 and 9.5.展开更多
基金Supported by the National Natural Science Foundation of China(Grant No.10675036)
文摘In order to compare the dosimetric properties of two kinds of solid state detectors used for monitoring ex- ternal exposures,experiments were performed for the GD-300 series of radiophotoluminescent glass detectors (RPLGD)and the GR-200 series of thermoluminescent detectors(TLD).X-rays and ^(137)Cs and ^(60)Coγ-rays were used to irradiate the RPLGDs and TLDs,their dose linearity,uniformity/reproducibility of signal,fading effect and energy dependence were compared.Both kinds of the detectors have generally good dosimetric properties.The dose linearity and energy dependence of the GD-351 dosimeters and the TLDs are nearly the same,but the RPLGD is much better than the TLD in terms of the uniformity and fading effect.
文摘In the fine-grain TL dating the full o dose must be converted into the equivalent P dose. The conversion is finished by Keff-value, which is an effective or effectiveness. But the Keff can not be measured directly for each sample and only the external radiative efficiency K3.7 can be measured. In order to obtain the Keff a special study for the conversion factor of Keff to K3.t has been made using the ultrathin TLD. The results show that the conversion factor of tile TLD for archaeological samples is 0.847, which is in agreement with calculated value 0.85.
文摘Pulsed photo-stimulated luminescence (PPSL) is a simple screening method that can be employed qualitatively at the spot for the detection of eggs treated with ionizing radiation.Due to the variations in the results during storage,the eggs of ostrich,duck,hen,and quail were irradiated to doses of 0,1,2,and 3 kGy.Most of the samples were incorrectly identified during storage after four months of irradiation.Thermoluminescence (TL) technique was also tried by using egg shells in order to confirm the irradiation treatment in eggs.TL glow curves were recorded between the temperatures 50℃to 400℃at the rate of 5°/s for all the control and irradiated samples.On the basis of integrated areas of first glow curves (TL1),the glow curve ratios (TL1/TL2) and the shapes of maxima of TL1, the irradiation treatment of all the eggs was confirmed.Furthermore,the presence of calcite and aragonite minerals that cause the TL signal in the egg shells were studied using X-ray diffraction spectrometry.
文摘Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food.Because of the rapid commercialization of irradiated foods throughout the world,compliance of different regulations relating to use of technology in different countries and demand of consum- ers for clear labelling of irradiated foods,there is need for the development of analytical methods to detect radiation treatment of food.Among several methods studied so far,thermoluminescence (TL) is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles.In this study,the irradiated and unirradiated wheat and rice samples were analyzed using the TL method.The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture (NIFA),Peshawar.The mineral contaminants were isolated by jet water,ultrasonic treatment,and density gradient.TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50—500℃using a TL reader.Generally,the glow curves for irradiated samples showed much higher TL intensities (TL_1) than the unirradiated samples.The results were normalized by re-irradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves (TL_2).The ratio of the area of first glow curve to that of second glow curve (TL_1/TL_2) was calcu- lated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples.Finally,the shapes of the glow curves for irradiated and unirradiated samples were also analyzed.On the ba- sis of these results (comparison of TL-intensities,TL_1/TL_2 ratios and shapes of the glow curves),all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.
文摘In routine thermoluminescence(TL) dating,there is often a tendency to omit an absolute determination of the thorium and uranium content in the sample and simply measure the total alpha count rate.The annual dose is then calculated assuming equal activities for a Th/U weight ratio of about 3.17. In fact this ratio is varied significantly in pottery.Calculation of the annual dose conversion factors from data using the total alpha count rate in a selected range of Th/U weight ratios shows significant differences.The results indicate that the additional error contribution to the final TL age is in the range ±2.5%to±4.1% for most cases where the Th/U ratio lies between 1.1 and 9.5.
