MCNP simulations of a glass display used in a mobile phone as an accident dosimeter

It has been demonstrated that glass display of mobile phones can be used as a device for accident dosimetry. Published studies concentrated on the experimental investigation of parts of the glass display. In the work presented here, the experimental results are compared with results of radiation transport calculations using the Monte Carlo code MCNP5.An experimental setup of an irradiation of an extracted glass display is simulated. The simulation is then extended to a simulation of a modern day mobile phone consisting of all major parts. Simulations are performed for various irradiation conditions and different geometric and material properties.The results of the simulation show a good agreement with the experiments for an extracted glass sample as well as for an actual modern mobile phone. The glass display is exposed to radiation in various angular and energy distributions. Simulated results were compared to experimentally determined results. The effects of the irradiation condition on the photon energy dependence were investigated and variations in the material constants of the display glass composition were discussed. This work affirms the usability of a mobile phone as a versatile and flexible accident radiation detector.     

新疆特克斯河下游河段断层活动性研究

新疆特克斯河上拟修建的恰普其海电站和山口电站位于断裂构造发育、新活动强烈的天山地区。野外地质研究表明，工程区的5条主要断层在第四纪均有活动。对采自工程区的特克斯河断层和F_1断层上的各种断层岩样品，应用变形岩石显微构造分析法、石英颗粒表面形貌法和热释光测年法进行了综合分析测试，结果表明，早期沿断层部位发生过慢速率的韧性变形作用，后沿韧性变形带发生脆性破裂。断层主活动期在上新世末期到早更新世，断层活动时的差异应力为130MPa,以挤压为主。更新世以后，断层活动强度大大减弱，但仍有明显活动，断层最后一次较强烈活动的下限时代为晚更新世末或全新世初。为确保工程安全，在最后确定场址时应尽可能避开活断层，在工程设计上也应增加一定的安全措施。     

嵌入式组合导航系统中多路异步串口的设计

随着捷联惯导技术的发展,高速数字信号处理芯片（DSP）在嵌入式组合导航系统中得到了广泛的应用,在这类器件中,大部分没有异步通信串口,使得其与低速设备的通信受到限制。为了使DSP与其他设备通过异步串口进行实时的数据交换,在剖析TL16C752B内部寄存器功能的基础上,结合其在嵌入式组合导航系统中的具体应用,重点研究了TL16C752B的FIFO通信方式的基本过程并设计了通用异步收发器（UART）初始化程序和中断方式接收数据程序。试验结果表明,利用TL16C752B的FIFO通信方式有效地解决了高速DSP和外部低速设备通过异步串口通信的问题,提高了系统串行通信的实时性和可靠性。     

Comparative investigations of TL and OSL in KCI:Eu2+ crystals irradiated with UV and X-rays

Abstract

We present thermoluminescence (TL) glow curves and optical stimulated luminescence (OSL) response from both KCl:Eu²⁺ crystals irradiated with soft X-rays (20 KV, 80 μA) and ultraviolet light (230 nm). Two situations take place. First, we observed that for long time F-light bleaching (560 nm) the typical TL glow curve of X-rays irradiated KCl:Eu²⁺ resembles the TL glow curve of UV-irradiated samples. Second, along with OSL measurements, we have performed a thermal bleaching and we have addressed F and F_z participation in OSL. These results provide us a supportable correlation between F and F_z as responsible centers for OSL and TL processes.     

一种基于简化左右手复合传输线的带通滤波器

根据等效介质理论和Bloch-Floquet理论,研究了简化左右手复合传输线(SCRLH TL:Simplified Composite Right/Left Handed Transmission Line)的等效介质参量(ε,μ)、等效折射率(n)和传播参量(γB,ZB)的频响特性;设计、制作了中心频率约为7.49...     

An algorithm for unified analysis on the thermoluminescence glow curve

An algorithm was developed to integrally handle excitation by radiation, relaxation and luminescence by thermal or optical stimulation in thermoluminescence (TL) and optically stimulated luminescence (OSL) processes. This algorithm reflects the mutual interaction between traps through a conduction band. Electrons and holes are created by radiation in the beginning, and these electrons move to the trap through the conduction band. These holes move to the recombination center through a valence band. The ratio of the electrons allocated to each trap differs with the recombination probability and these values also relevant to the process of luminescence. Accordingly, the glow curve can be interpreted by taking the rate of electron–hole pairs created by ionizing radiation as a unique initial condition. This method differs from the conventional method of interpreting the measured glow curve with the initial electron concentration allocated to each trap at the end of irradiation. A program using the Visual Studio's C# subsystem was made to realize such a developed algorithm. To verify this algorithm it was applied to LiF:Mg,Cu,Si. The TL glow curve was deconvoluted with a model of five traps, one deep trap and one recombination center (RC).     

Thermoluminescence and optically stimulated luminescence characteristics of Al2O3 doped with Tb

In the present work policrystals of α − Al₂O₃ doped with terbium were synthesized using the solvent evaporation method. The samples were prepared using Al(NO₃)₃·9H₂O and Tb(NO₃)₃·5H₂O reagents, with Tb concentrations between 1 and 5 mol% and thermally treated at high temperature above ∼1400 °C. X-ray diffraction measurements showed the α-phase formation of samples. TL glow curve presented an intense peak at ∼190 °C and two other with low intensity at 290 and 350 °C after gamma irradiation. The best doping concentration which presented high luminescence was the sample doped with 3 mol% of Tb. TL spectra and fluorescence measurements showed similar luminescence spectra with lines attribute to Tb³⁺ ions. A linear behavior to gamma dose between 1 and 20 Gy was observed in TL, using 190 °C peak as well as in OSL signal, this last carried out using 532 nm wavelength stimulation.     

Feasibility study of CaSO4:Eu,CaSO4:Eu,Ag and CaSO4:Eu,Ag(NP) as thermoluminescent dosimeters

This work evaluates the dosimetric properties of crystals of CaSO₄ doped with unusual elements, such as europium (Eu) and silver (Ag), including their nanoparticle forms, after the incorporation of glass or Teflon and compares them with well-known thermoluminescent dosimeters (TLD). X-ray diffraction analyses showed that samples of doped CaSO₄ exhibit only a single phase corresponding to the crystal structure of anhydrite. Optical spectroscopy confirmed the presence of Eu³⁺ in the crystal matrix and a luminescent gain due the presence of silver nanoparticles. The composites showed thermoluminescent emission glow curves, with a single peak centered at approximately 200 °C for pellets with Teflon and at 230 °C for pellets with glass. The dosimeters based on calcium sulfate doped with europium and silver nanoparticles provided the most intense thermoluminescent (TL) emission of the composites studied. In comparison with commercial TLD, such as LiF:Mg,Ti and CaSO₄:Dy, the CaSO₄:Eu,Ag(NP)+glass produced in this work presented similar low detection limits and higher sensitivity. The new methods for the preparation of dosimeters and the incorporation of glass are shown to be viable because all of the samples presented a linear, reproducible and first order kinetic TL emission.     

The thermoluminescence response of Ge-doped optical fibre subjected to photon irradiation

A radiation dosimeter based on Ge-doped silica fibre is described. Parameters concerning thermoluminescence (TL) induced by ⁶⁰Co irradiation are investigated, including activation energies, frequency factors, and reproducibility with dose and fading. It is concluded that Ge-doped silica fibres provide a good basis for medical radiation dosimetry at therapy levels. In particular, doses are reproducible to within 3%, the fibres are reusable and show linearity of dose versus TL output over the approximate range of dose 1 Gy to in excess of 100 Gy. At room temperatures, fading within the first 30 d following irradiation has been found to be of the order of 7%.     

Performance parameters and uncertainty of the method for assessment of Sr concentration in small powder samples using α-Al2O3:C beta detectors

Non-destructive detection of very low concentrations of ⁹⁰Sr (about 0.4 Bq g⁻¹) inside powdered samples with masses below 200 mg (such as tooth enamel prepared for EPR measurements) is not a trivial task. Most of the conventional measurement techniques require a special chemical treatment or an enrichment process. Thin-layer α-Al₂O₃:C passive luminescence beta detectors have been successfully used for measuring dose rates due to beta decay of ⁹⁰Sr inside small samples. In this paper, a new refinement is introduced for the assessment of ⁹⁰Sr concentration in dental tissue using thin-layer α-Al₂O₃:C passive luminescence beta detectors. The performance parameters of passive luminescence beta detection (such as detection and quantification limits) have been evaluated using statistical analysis of the experimental results. The sources of uncertainty have been analyzed and the total uncertainty calculated using Monte Carlo simulations. The results of TL passive beta detection for measurement of ⁹⁰Sr concentrations are shown to be in good agreement with those obtained using low-level beta counting.