热释光油气勘查的机理模型与实验

多年放射性油气勘查工作研究发现,多数油气藏上方存在放射性异常区.但是,油气藏与其上方放射性异常区是否存在必然联系尚无定论.本文就地表砂土热释光勘查油气藏的机理模型,进行了室内微缩模拟实验,试图证明油气迁移可以引起其上方地层中放射性元素的重新分布与富集.实验中排除了环境辐射差异、地下水活动、地形变化、土质不同等带来的干扰,观察到油气藏上方土层中放射性元素重新分布的迹象.结合前期研究工作可以认为,"油气迁移引起上覆地层中放射性元素重新分布"的假设成立,为研究地表热释光油气勘查方法提供了进一步的理论和事实依据.     

The effect of lithium fluoride on the thermal stability and thermoluminescence properties of borosilicate glass and glass-ceramics

The oxyfluoride glass and glass-ceramics from the LiF-B₂O₃-SiO₂ system are developed. The stable glass can be produced in the range of 20–40 mol% LiF. The effect of LiF admixture on the thermal stability of the glass as well as the thermoluminescence (TL) properties such as glow curves shape is studied. The results show that the increase of lithium fluoride content in the borosilicate glass causes efficiency enhancement of the thermoluminescence signal. We have clearly stated that the process of controlled crystallization of the oxyfluoride glasses can lead again to increased intensity of the TL process. The glass-ceramics with 40 mol% LiF reveals similar level of TL signal to commercially used doped LiF material and can be considered as active material for alpha and beta radiation detectors.     

热释光计量仪在鱼耳石成因矿物学研究中的应用

利用FJ427A1型微机热释光剂量仪对采自河北白洋淀及北京密云水库的45尾野生鲤鱼的鱼耳石进行热释光特征研究。结果表明,以上两个不同水域鱼耳石的热发光曲线的峰高、半高宽、峰位等参数均存在明显差异,与水体的水质特点呈较好的相关性。此外,热释光半高宽,尤其是第二峰半高宽可以作为区分两个不同污染程度水域的生物矿物学标型。     

湖南水口山矿区石英的热释光特征及找矿意义

对湖南水口山矿区硅化角砾岩体中的石英进行了热释光分析.石英的热释光特征与成矿作用密切相关,热释光特征能较好反映出成矿信息.石英的热释光强度(峰值)与成矿强度呈正相关关系,天然热释光峰值大,成矿强度也大.天然热释光具有310℃-330℃的发光峰反映成矿强烈,人造热释光具有200℃-220℃的发光峰则反映金成矿作用强.热释光分析可作为重要的找矿指标之一.     

Optical studies of Y_3(Al,Ga)_5O_(12):Ce~(3+),Cr~(3+),Nd~(3+) nano-phosphors obtained by the Pechini method

The Y3(AI,Ga)_5O_(12):Ce~(3+),Cr~(3+),Nd~(3+)(YAGG) nano-phosphors with homogeneous particle-size distribution,low aggregation and average crystalline size of about 65 nm were obtained using a modified Pechini method.Only slight aggregation of the crystallites occurs after post-annealing at 1100℃.The intense Ce~(3+)bands in the excitation spectra of the Ce~(3+),Cr~(3+),Nd~(3+)co-doped materials monitoring the Cr~(3+) emission at 690 nm indicate energy transfer from Ce~(3+) to Cr~(3+).Weak Nd~(3+) lines are observed,as well.In addition,the emission of Nd~(3+)at 1060 nm with excitation of Ce~(3+) and Cr~(3+) confirms the Ce~(3+)/Cr~(3+)to Nd~(3+)energy transfer.The short average luminescence decay times for the Ce~(3+) emission indicate the Ce~(3+)/Cr~(3+)to Nd~(3+)energy transfer.Eventually,the Y_3(AI,Ga)_5O_(12):Ce~(3+),Cr~(3+),Nd~(3+) nano-phosphors exhibit persistent luminescence originating from the 4f~3→4f~3 transitions of Nd~(3+) which matches well to the first biological window to be used in bioimaging applications.     

UV–VUV spectroscopy of rare earth doped persistent luminescence materials

The electronic and defect energy level structure of polycrystalline SrAl₂O₄:Eu²⁺,R³⁺ persistent luminescence materials were studied with thermoluminescence and UV–VUV synchrotron radiation emission and excitation spectroscopy. Theoretical calculations using the density functional theory (DFT) were carried out simultaneously with the experimental work. The experimental band gap energy (E_g) value of 6.6 eV agrees very well with the DFT value of 6.4 eV. The 4f⁷ → 4f⁶5d¹ excitation bands of Eu²⁺ were found rather similar irrespective of the R³⁺ co-dopant. The trap level energy distribution depended strongly on the R³⁺ co-dopant except for the shallowest trap energy above the room temperature remaining the same, however. The different processes in the mechanism of persistent luminescence from SrAl₂O₄:Eu²⁺,R³⁺ was constructed and discussed.     

Thermoluminescence properties of Al doped ZnO nanoparticles

ZnO nanoparticles doped with aluminum (AZO nanoparticles) were investigated using low temperature thermoluminescence (TL) and structural characterization experiments. TL experiments were performed on AZO nanoparticles in the temperature range of 10–300?K. TL curve presented one intensive peak around 123?K and two overlapped peaks to intensive peak around 85 and 150?K for heating rate of 0.1?K/s. Curve fitting and initial rise methods were used to find the activation energies of associated trapping centers. Analyses resulted in the presence of three centers at 0.05, 0.08 and 0.17?eV with peak maximum temperatures (T_m) of 86.2, 121.5 and 147.1?K, respectively. TL experiments were expanded using different heating rates between 0.1?K/s and 0.5?K/s. Behavior of revealed traps was investigated using an experimental technique called as T_m??T_stop method. It was seen that traps are quasi-continuously distributed within the band gap. Structural properties were studied using x-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy experiments.     

Optically stimulated luminescence: Searching for new dosimetric materials

Optically stimulated luminescence (OSL) is increasingly being used as a dosimetric technique in various fields such as medical, environmental and space dosimetry, and sediment and archaeological dating. Nevertheless few compounds are suitable as OSL materials. In this work, a survey was made of various insulators, searching for candidates for new OSL dosimeters. Natural and synthetic crystals and glasses from numerous sources are included. Luminescence was stimulated with blue LEDs (470 nm) and with IR laser (830 nm) provided by an automatic reader. Irradiation was performed with a ⁹⁰Sr/⁹⁰Y beta source, and the emitted light was measured with a photomultiplier tube, protected with suitable optical filters. Thermoluminescence (TL) of the samples was also measured, with the same equipment, to evaluate the thermal and optical stability of the defects related to OSL and TL. Among the various investigated materials, Al₂O₃:Cr, Mg, Fe, MgAl₂O₄ spinels, Mg₂SiO₄:Tb, and natural fluorite show potential as OSL dosimeters. Some materials, as barium aluminoborate glasses, although showing intense OSL signals, present a high fading at room temperature. In that situation the OSL signal is related to low temperature TL peaks that also fade at room temperature. None of the investigated materials was specially prepared to be used as an OSL dosimeter, which means that work can be done, mainly in the impurity nature and content, in order to improve OSL signals and to overcome some of the shortcomings that were noticed.     

亚太地区放射性个人剂量监测国际比对与思索

报告了参加亚太地区放射性个人剂量监测国际比对的结果,并提出了一些看法。     

Thermoluminescence properties of Ce-doped LiSr4(BO3)3 phosphor

Borates LiSr₄(BO₃)₃ were synthesized by high-temperature solid-state reaction. The thermoluminescence (TL) and some of the dosimetric characteristics of Ce³⁺-activated LiSr₄(BO₃)₃ were reported. The TL glow curve is composed of only one peak located at about 209 °C between room temperature and 500 °C. The optimum Ce³⁺ concentration is 1 mol% to obtain the highest TL intensity. The TL kinetic parameters of LiSr₄(BO₃)₃:0.01Ce³⁺ were studied by the peak shape method. The TL dose response is linear in the protection dose ranging from 1 mGy to 1 Gy. The three-dimensional thermoluminescence emission spectra were also studied, peaking at 441 and 474 nm due to the characteristic transition of Ce³⁺.