Acquisition of a Helium 3 Refrigerator for Synchrotron X-ray Studies

9625919 Chan X射线散射为凝聚物质系统的微观性质提供了一个极其强大的探测器。拟议的3He制冷系统以及相关的电子和气体处理部件将允许我们在低温下将X射线散射技术应用于材料系统，特别是量子液体。这种能力在世界上任何同步加速器x射线源上都不具备。因此，这种3He制冷系统将提供一种独特的、有价值的设施。拟议的制冷系统最初将用于研究氦混合物中的无序和杂质。这种无序可以通过引入退火杂质，如4He中的3He，或限制在多孔玻璃中，如Vycor或气凝胶，或两者兼而有之。无序的存在会对3He-4He混合物的临界行为、输运性质和相分离产生深远的影响。它还可以改变微观结构，这反映在原子的对关联函数上。这项研究将利用X射线散射直接解决这些微观问题。这项研究将利用目前在布鲁克海文国家实验室运行的国家同步加速器光源，或正在阿贡国家实验室建造的先进光子光源。拟议的制冷系统的设计将具有足够的灵活性，使其能够在这两个来源的各种仪器上使用。该项目将对低温材料研究领域产生广泛的科学影响，并将为重要的X射线散射领域提供独特的能力，促进具有经济意义的材料的表征。***

9625919 Chan X-ray scattering provides an extremely powerful probe of the microscopic properties of condensed materials systems. The proposed 3He refrigeration system and associated electronics and gas handling components will allow us to apply X-ray scattering techniques to materials systems at low temperatures, in particular quantum liquids. Such capabilities are not available at any synchrotron x-ray source in the world. Thus, this 3He refrigeration system will provide a unique and valuable facility. The proposed refrigeration system will be initially used for the study of disorder and impurities in helium mixtures. This disorder can be introduced either through the introduction of annealed impurities, such as 3He in 4He, or confinement in porous glasses, such as vycor or aerogel, or both. The presence of disorder can have profound effects on the critical behavior, transport properties and phase separation of 3He-4He mixtures. It can also modify the microscopic structure, as reflected in the pair correlation function of the atoms. The research studies will directly address these microscopic issues using x-ray scattering. The research will make use of either the National Synchrotron Light Source currently operating at Brookhaven National Laboratory or the Advanced Photon source which is under construction at Argonne National Laboratory. The proposed refrigeration system will be designed with sufficient flexibility to allow it to be used on a variety of instruments at either of these sources. %%% This project will have broad scientific impact to the field of low temperature materials research and will provide unique capability to the important area of x-ray scattering for the advancement of characterization of materials of economic importance. ***