Solid Dosimetric Detector and Method Laboratory

Beijing, China

Solid Dosimetric Detector and Method Laboratory

Beijing, China

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Li H.,Beijing University of Technology | Zhang L.,Solid Dosimetric Detector and Method Laboratory | Guo Q.,Beijing University of Technology
Radiation Protection Dosimetry | Year: 2012

Passive measuring devices are comprehensively employed in thoron progeny surveys, while the deposition velocity of thoron progeny is the most critical parameter, which varies in different environments. In this study, to analyse the influence of environmental factors on thoron progeny deposition velocity, an improved model was proposed on the basis of Lai's aerosol deposition model and the Jacobi's model, and a series of measurements were carried out to verify the model. According to the calculations, deposition velocity decreases with increasing aerosol diameter and also aerosol concentration, while increases with increasing ventilation rate. In typical indoor environments, a typical value of 1.26x10-5m s-1 is recommended, with a range between 7.6x10-7 and 3.2x10-4 m s-1. © The Author 2012. Published by Oxford University Press. All rights reserved.


Guo L.,Beijing University of Technology | Zhang L.,Solid Dosimetric Detector and Method Laboratory | Guo Q.-J.,Beijing University of Technology
Yuanzineng Kexue Jishu/Atomic Energy Science and Technology | Year: 2016

Radon and its progeny contribute half of all radiation exposure of the public received from natural radiation, while the unattached fraction of radon progeny plays an important role on its dose conversion factor. To understand better on the variation of the unattached fraction of radon progeny and how environmental factors work on it, both 24 h integrated monitor and real-time continuous monitor were adopted by this study for the observation on annual variation and diurnal variation as well. The results of monthly field measurement show that the annual average of the unattached fraction of radon progeny is 8.8% (6.4%-12.5%) and 9.7% (4.9%-12.8%) for indoor and outdoor, respectively. In indoor environments, the unattached fraction of radon progeny is more stable compared with that of outdoors since indoor environmental factors are more stable. For diurnal variation, even though radon equilibrium equivalent concentration has a disciplinarian variation, higher in the morning and lower in the afternoon, the variation of the unattached fraction of radon progeny does not show any regularity. © 2016, Editorial Board of Atomic Energy Science and Technology. All right reserved.


Guo L.,Beijing University of Technology | Zhang L.,Solid Dosimetric Detector and Method Laboratory | Guo Q.,Beijing University of Technology
Journal of Radiological Protection | Year: 2016

The unattached fraction of radon progeny is one of the most important factors for radon exposure evaluation through the dosimetric approach. To better understand its level and variation in the real environment, a series of field measurements were carried out indoors and outdoors, and radon equilibrium equivalent concentration was also measured. The dose contribution of unattached radon progeny was evaluated in addition. The results show that no clear variation trend of the unattached fraction of radon progeny is observed in an indoor or outdoor environment. The average unattached fraction of radon progeny for the indoors and outdoors are (8.7 ± 1.6)% and (9.7 ± 2.1)%, respectively. The dose contribution of unattached radon progeny to total radon exposure is some 38.8% in an indoor environment, suggesting the importance of the evaluation on unattached radon progeny. © 2016 IOP Publishing Ltd.


PubMed | Solid Dosimetric Detector and Method Laboratory and Beijing University of Technology
Type: Evaluation Studies | Journal: Radiation protection dosimetry | Year: 2015

Alpha spectrum measurement is one of the most important methods to measure radon progeny concentration in environment. However, the accuracy of this method is affected by the peak tailing due to the energy losses of alpha particles. This article presents a peak shape fitting method that can overcome the peak tailing problem in most situations. On a typical measured alpha spectrum curve, consecutive peaks overlap even their energies are not close to each other, and it is difficult to calculate the exact count of each peak. The peak shape fitting method uses combination of Gaussian and exponential functions, which can depict features of those peaks, to fit the measured curve. It can provide net counts of each peak explicitly, which was used in the Kerr method of calculation procedure for radon progeny concentration measurement. The results show that the fitting curve fits well with the measured curve, and the influence of the peak tailing is reduced. The method was further validated by the agreement between radon equilibrium equivalent concentration based on this method and the measured values of some commercial radon monitors, such as EQF3220 and WLx. In addition, this method improves the accuracy of individual radon progeny concentration measurement. Especially for the (218)Po peak, after eliminating the peak tailing influence, the calculated result of (218)Po concentration has been reduced by 21 %.


PubMed | Solid Dosimetric Detector and Method Laboratory and State Key Laboratory of NBC Protection for Civilian
Type: Comparative Study | Journal: Radiation protection dosimetry | Year: 2015

One of the most important characteristics of thermoluminescent detectors, if they are intended to be used in a wide range of energies, is their energy response. A comparison of the energy characteristics of the newly developed LiF:Mg,Cu,P chips with additional PbO doping (GR-200E) against GR-200A LiF:Mg,Cu,P was attempted to improve further the accuracy of personal dosimetry. Hp(10) energy response of GR-200E is quite different from that of GR-200A. For GR-200E, the anomalous energy response can be eliminated and the over-response to low-energy photons should be filtered properly. The GR-200E under the copper filter provided results within 4 % with respect to the conventional quantity value over the energy range from 65 to 1250 keV. The ratio of the Hp(10) response of the Cu-covered filters for GR-200A to that of those covered with plastic for GR-200E is a very good tool for identifying the radiation quality in the range studied. The accuracy in the dose evaluated from TLD measurements can be greatly increased.


PubMed | Solid Dosimetric Detector and Method Laboratory and State Key Laboratory of NBC Protection for Civilian
Type: Journal Article | Journal: Radiation protection dosimetry | Year: 2015

The 3-D thermoluminescence spectra and glow curves of LiF:Mg,Cu,Si, LiF:Mg,Cu, LiF:Mg,Si and LiF:Cu,Si with low concentrations of Mg and Cu were measured and were compared with those with high concentrations to investigate further the role of dopants in LiF:Mg,Cu,Si material. The shape of glow curves of the four samples is similar; however, LiF:Cu,Si sample had no Mg dopant. It is concluded that the TL emission to be from self-trapped excitons in LiF, and this emission could be enhanced and altered by Mg, Cu and Si dopants in LiF:Mg,Cu,Si; all three dopants are necessary to obtain the bright TL emission and may be involved in the luminescence process; Mg seems to be the most essential dopant and Cu is involved in the trapping although the role of Mg dominates; both Cu and Si play a role in the main emission process and Cu also plays a role in reducing the emission around 610 nm.


PubMed | Solid Dosimetric Detector and Method Laboratory and State Key Laboratory of NBC Protection for Civilian
Type: Comparative Study | Journal: Radiation protection dosimetry | Year: 2016

The influence of various annealing treatments on radioluminescent (RL) and thermoluminescent (TL) spectra of LiF:Mg,Cu,Si and LiF:Mg,Cu,P was investigated. The TL and RL emission bands for LiF:Mg,Cu,P are not the same; however, the emission band peaking at 383 nm is predominant in the TL and RL emission for LiF:Mg,Cu,Si. With the increase in annealing temperatures in the range of 240-300C, for LiF:Mg,Cu,P, the intensity of TL decreases much more rapidly than that of RL. For LiF:Mg,Cu,Si, the area ratios of the two bands of RL and TL remain constant within experimental errors. It suggests that there is a significant decrease in the concentration of recombination centres in LiF:Mg,Cu,P after the annealing, in addition to the decrease in trapping centres, the recombination centres for main TL emission and RL emission in LiF:Mg,Cu,Si are the same, and the recombination centres for TL emission and RL emission in LiF:Mg,Cu,P are not the same. P is a more effective dopant than Si.


Tang K.,Solid dosimetric detector and method laboratory | Cui H.,Solid dosimetric detector and method laboratory | Zhu H.,Solid dosimetric detector and method laboratory | Liu Z.,Solid dosimetric detector and method laboratory | Fan H.,Solid dosimetric detector and method laboratory
Radiation Protection Dosimetry | Year: 2013

The 3D thermoluminescent spectra and glow curves of LiF:Mg,Cu,Si with various Mg, Cu and Si concentrations were measured. The shapes of the glow curves in LiF:Mg,Cu,Si, LiF:Mg,Cu and LiF:Mg,Si are similar and the glow curves have peaks at approximately the same temperatures, but with significantly different intensities. Neither the temperature of the glow peak nor the wavelength of the emission maximum changes with variation of dopants concentrations when Cu is more than 0.01 mol % in LiF:Mg,Cu,Si. The spectrum structure in LiF:Mg,Cu,Si, LiF:Mg,Cu and LiF:Mg,Si is similar in the 300- 550 nm range. Some weak emissions around 610 nm are shown in LiF:Mg,Cu,Si with a Cu concentration of 0.01 mol % and in LiF:Mg,Si. It is concluded that Mg dopant mainly plays a role in the formation of trapping centres, both Cu and Si play a role in the main emission process and Cu also plays a role in reducing the emission around 610 nm. © The Author 2013. Published by Oxford University Press. All rights reserved.


Tang K.,Solid Dosimetric Detector and Method Laboratory | Cui H.,Solid Dosimetric Detector and Method Laboratory | Zhu H.,Solid Dosimetric Detector and Method Laboratory | Liu Z.,Solid Dosimetric Detector and Method Laboratory | Fan H.,Solid Dosimetric Detector and Method Laboratory
Radiation Measurements | Year: 2013

The dependence of thermoluminescence (TL) of LiF:Mg,Cu,Si on sintering temperatures and dopants concentrations were investigated. The dependency of the TL in LiF:Mg,Cu,Si on sintering temperature exhibits a very sharp maximum at 830 °C. LiF:Mg,Cu,Si is much too sensitive than LiF:Mg,Cu,P to sintering temperature. The glow curve and the TL sensitivity depend on the concentration of Mg, Cu and Si, showing a distinct maximum for certain concentrations of these impurities. Mg seems to be the most essential dopant, as very small changes of the Mg content strongly influence both the glow curve and the TL sensitivity. Si is the main activator responsible for TL emission. The stability to heat treatments in LiF:Mg,Cu,Si was influenced greatly by Mg concentrations. The thermal instability in LiF:Mg,Cu,Si is caused not by Cu and Si but Mg ion state change. It was found that the optimum concentrations are Mg:0.6 mol%, Cu:0.03 mol% and Si:0.9 mol% for this material, which showed the best stability to heat treatment. © 2012 Elsevier Ltd. All rights reserved.


Tang K.,Solid Dosimetric Detector and Method Laboratory | Cui H.,Solid Dosimetric Detector and Method Laboratory | Zhu H.,Solid Dosimetric Detector and Method Laboratory | Liu Z.,Solid Dosimetric Detector and Method Laboratory | Fan H.,Solid Dosimetric Detector and Method Laboratory
Radiation Measurements | Year: 2012

The preparation method and some dosimetric properties of the new LiF:Mg,Cu,Si discs are presented. The effect of heat treatments on LiF:Mg,Cu,Si was investigated. The shape of the glow curve for LiF:Mg,Cu,Si is similar to that for standard LiF:Mg,Cu,P (GR-200A), and shows minimal differences when annealed in the range from 260°C to 290°C for 10 min. The TL sensitivity for LiF:Mg,Cu,Si is much lower than that for GR-200A, but is 35 times larger than that for TLD-100 and is slightly higher than that for HMCP. The height of the high-temperature peaks for LiF:Mg,Cu,Si is not only lower than that for GR-200A, but also lower than that for HMCP. The glow curve shape of LiF:Mg,Cu,Si annealed at 260°C for different times shows minimal differences and TL response remains stable. These results indicate that the new LiF:Mg,Cu,Si disc has a good stability to thermal treatments and a lower residual TL signal. © 2011 Elsevier Ltd. All rights reserved.

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