Al-Hinai Khalid H, Benkara Mohd Nadjima, Rozullyah Zulkepely Nurul, Md Nor Roslan, Mohd Amin Yusoff, Bradley D A
Department of Physics, University of Malaya, 50603 Kuala Lumpur, Malaysia.
Appl Radiat Isot. 2013 Dec;82:126-9. doi: 10.1016/j.apradiso.2013.07.013. Epub 2013 Aug 2.
We describe two example pilot efforts to help define new thermoluminescent dosimeter media. The first concerns ZnS:Mn nanophosphors, prepared by chemical precipitation using zinc and sodium sulfate, doped with manganese sulfate at concentrations varying from 1 to 3mol. The second concerns chemical vapor deposited diamond, produced as a thin film or as amorphous carbon on a single-crystal silicon substrate, each deposited under the same conditions, use being made of the hot filament-chemical vapor deposition (HFCVD) technique. The gas concentrations used were 1% CH4 in 99% H2 and 25% CH4 in 75% H2. Characterization of formations used FESEM, XRD and EDX. The nanophosphors consisted of particles of sizes in the range 85-150nm, the thermoluminescence (TL)-based radiation detection medium giving rise to a single peaked glow curve of maximum yield at a temperature of 250°C at a heating rate of 5°C/s. The TL response increased linearly with radiation dose, ZnS doped to 2mol of Mn being found the most sensitive. Regarding chemical vapor deposited (CVD) carbon, inappreciable TL was found for the resultant ball-like amorphous carbon films, graphite, and the silicon substrate, whereas CVD diamond films showed a promising degree of linearity with dose. For both the ZnS and diamond samples, TL signal fading was appreciable, being some 40% per day for ZnS and>50% per day for CVD films even under storage in the dark at room temperature, making it apparent that there is need to adjust parameters such as the size of nanoparticles.
我们描述了两项有助于定义新型热释光剂量计介质的试点工作示例。第一项涉及通过使用锌和硫酸钠进行化学沉淀制备的ZnS:Mn纳米磷光体，掺杂有浓度从1到3mol不等的硫酸锰。第二项涉及化学气相沉积金刚石，它以薄膜形式或在单晶硅衬底上作为非晶碳产生，每种都在相同条件下沉积，采用热丝化学气相沉积（HFCVD）技术。使用的气体浓度为99%H2中1%CH4和75%H2中25%CH4。对形成物的表征使用了场发射扫描电子显微镜（FESEM）、X射线衍射（XRD）和能量色散X射线光谱（EDX）。纳米磷光体由尺寸在85 - 150nm范围内的颗粒组成，基于热释光（TL）的辐射检测介质在5°C/s的加热速率下，在250°C温度处产生具有最大产率的单峰发光曲线。TL响应随辐射剂量线性增加，发现掺杂2mol Mn的ZnS最敏感。关于化学气相沉积（CVD）碳，对于所得的球状非晶碳膜、石墨和硅衬底，发现TL不明显，而CVD金刚石膜显示出与剂量有良好的线性关系。对于ZnS和金刚石样品，TL信号衰减都很明显，即使在室温黑暗中储存，ZnS每天约衰减40%，CVD膜每天衰减>50%，这表明显然需要调整诸如纳米颗粒尺寸等参数。
