MRI-R2: Development of a High-Flux Deuteron-Deuteron Fusion Neutron Source for 40Ar/39Ar Geochronology

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。 该项目将开发一种设施，利用氘原子和离子的核聚变产生具有245万电子伏均匀能量的大浓度中子。 聚变反应已经在以前的实验中成功地诱导，但该项目将使用一种新的径向向内聚焦氘离子束几何形状，以追求比以前高1000倍或更多倍的中子浓度。 该中子发生器将用于照射地质样品，以进行氩-40/氩-39定年方法，在该方法中，钾-39必须通过中子捕获转化为氩-39。这种广泛使用的定年方法的中子源以前是由铀裂变提供动力的传统核反应堆，产生了广泛的中子能量，具有几种次优效应。相比之下，该项目将开发的设备将减少原子反冲和不必要的核反应，从而产生更准确的年龄信息，对分析人员的辐射风险较小，并且不会产生危险的放射性废物。这些改进将提高精确测定粘土等细粒矿物的年代的能力，粘土的年代通常可作为石油和矿石存款勘探的指南。其他可能的应用包括人类进化和早期太阳系的年表。该设备将用于测年以外的应用，特别是包括微量元素地球化学，核医学，材料科学和凝聚态物理学。提供快速中子活化数据的能力将适用于下一代核动力裂变反应堆的设计。该项目将为学生和博士后研究人员提供培训，从而有助于补充具有核科学专门知识的早期职业科学家的枯竭管道，从而解决国家安全和能源需求引起的日益严重的关切。该项目还将加强核科学家和地球科学家之间的跨学科合作。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). This project will develop a facility to use nuclear fusion of deuterium atoms and ions to create a large concentration of neutrons with uniform energy of 2.45 million electron volts. The fusion reaction has been successfully induced in previous experiments, but this project will use a novel radially inward-focussing deuterium ion beam geometry to pursue a neutron concentration 1000 or more times higher than previously achieved. This neutron generator will be used to irradiate geological samples for the argon-40/argon-39 dating method, in which potassium-39 must be converted to argon-39 through neutron capture. The source of neutrons for this widely used dating method has previously been conventional nuclear reactors powered by fission of uranium, producing a broad range of neutron energies with several suboptimal effects. In contrast, the device to be developed by this project will reduce atomic recoil and unwanted nuclear reactions, thus producing more accurate age information with less radiological risk to analysts, and without generating hazardous radioactive waste. These improvements will enhance the ability to accurately date fine-grained minerals such as clays, whose ages are often useful as a guide for petroleum and ore deposit exploration. Other likely applications include the chronology of human evolution and of the early solar system. The device will be useful for applications beyond dating, specifically including trace element geochemistry, nuclear medicine, materials science, and condensed matter physics. The ability to provide rapid neutron activation data will be applicable to the design of a next generation of fission reactors for nuclear power. The project will provide training to students and postdoctoral researchers and thus contribute to replenishing the depleted pipeline of early career scientists with expertise in nuclear sciences, thereby addressing growing concerns arising from national security and energy needs. The project will also enhance cross-disciplinary collaboration between nuclear scientists and earth scientists.