Pb-Qdot Direct Gamma Detectors

描述(申请人提供)：辐射探测器的一个关键属性是停止功率，它描述探测器收集辐射的效率。为了最大限度地减少患者的剂量，增加阻止功率是有帮助的，因为停止功率与获得高质量患者图像所需的剂量成反比。阻止功率与探测器材料的有效原子序数密切相关。放射设备的设计者更愿意用铅等有效原子序数非常高的材料来建造辐射探测器。不幸的是，大多数具有较高阻止能力的元素不是很好的辐射探测器材料，因为电荷(由探测器中的辐射产生)不容易从探测器材料中移出。因此，放置在探测器外部的仪器无法测量探测器材料中的辐射引起的电荷。将电荷从探测器内部移入外部世界(在那里可以测量电荷)的过程称为“电荷传输”。在第一阶段，我们证明了通过将创造高阻挡能力的目标与有利的电荷传输的挑战分开，有可能切断探测器规格的高难度结。这种分离是通过创建一个基质来实现的，在这个基质中，由高原子序数材料(即硫化铅)制成的量子点散布在硅基质中。量子点是原子的小集合，具有与这些原子的整体版本不同的电学性质。我们利用硫化铅的高阻挡能力和量子点良好的电学性质，将辐射高效地转化为电荷。我们利用硅基质有效地将电荷从量子点传输到硅基质的表面，从而使电荷能够被放大，并向外部仪器提供强大的信号。使用硅作为主体矩阵的另一个好处是，我们展示了我们可以在与辐射探测器相同的材料上构建电路元件(例如，放大器组件)。在证明了可行性后，我们的下一个目标是通过优化探测器质量为产品商业化做好准备。该项目是纳米技术首次成功应用于直接转换辐射探测。它承诺减少患者的辐射剂量，并降低医疗保健成本。除了诊断放射学市场，该平台技术还将用于国土安全以及面向消费者和国防市场的广谱监控，并有可能对太阳能行业产生交叉影响。

DESCRIPTION (provided by applicant): A critical property of radiation detectors is stopping power, which describes the efficiency of the detector in collecting radiation. In order to minimize patient dose, it is helpful to increase stopping power, since stopping power is inversely related to the dose required for obtaining high-quality patient images. Stopping power is strongly related to the effective atomic number of the detector material. Designers of radiological devices would prefer to build radiation detectors from materials with very high effective atomic numbers, such as lead. Unfortunately, most elements with higher stopping powers are not good candidates as radiation detector materials, because electrical charges (created by radiation in the detector) cannot be easily moved out of the detector material. As a result, instruments placed outside the detector are unable to measure the charges caused by radiation in the detector material. The process of removing charge from the inside of the detector into the outside world (where that it can be measured) is called "charge transport". In Phase I, we showed that it was possible to cut the Gordian knot of detector specification, by separating the goal of creating high stopping power from the challenge of favorable charge transport. This separation was accomplished by creating a matrix in which quantum dots made of high-atomic- number material (i.e., lead sulfide) were interspersed within a silicon matrix. Quantum dots are small collections of atoms that have different electrical properties than the bulk versions of these atoms. We used the high stopping power property of the lead sulfide, and the favorable electrical properties of the quantum dots, to convert radiation into charge with high efficiency. We used the silicon matrix to transport the charges effectively from the quantum dots to the surface of the silicon matrix, so that the charges could be amplified and provide strong signals to outside instruments. An additional benefit of using silicon as the host matrix was that we showed we could build circuit elements (e.g., amplifier components) on the same material as the radiation detector. Having demonstrated feasibility, our next goal is to ready the product for commercialization by optimizing detector quality. This project represents the first successful application of nanotechnology to direct-conversion radiation detection. It promises to reduce radiation dose to patients and to lower health care costs. In addition to the diagnostic radiology market, the platform technology will be useful for homeland security and broad-spectrum surveillance for the consumer and defense markets, with potential cross-fertilization to the solar power industry.