U.S.-U.K. Cooperative Research: Momentum Distributions in Quantum Liquids

这个为期三年的奖项支持宾夕法尼亚州立大学的Paul A. Sokol和英国斯塔福德郡基尔大学的William G. Stirling在凝聚态物理方面的美英合作研究。研究人员建议对量子液体进行一系列的中子散射研究。该合作将利用ISIS（卢瑟福阿普尔顿实验室）和IPNS脉冲中子源（阿贡国家实验室）独特的中子散射仪器。他们将研究量子效应主导微观性质的系统，以及液氦的最终状态效应，液氦混合物的性质以及限制几何对液氦动量分布的影响。美国和英国的研究人员都将他们的实验专业知识带到这次合作中，并将与他们的学生共同进行测量和数据分析。英国仪器具有测量量子液体动量分布的能力。这将由阿贡光谱仪的温度、压力和浓度测量来补充。液氦是超导的重要元素。量子效应支配着氦凝聚相的行为，并负责其独特的性质，如超流动性。通过对动量分布的研究，研究人员将对这些系统的微观动力学有一个独特的看法和重要的见解。提议的联合研究代表了对液体动量分布的详细调查，并将大大增加我们的知识。

This three-year award supports U.S.-U.K. cooperative research in condensed matter physics between Paul A. Sokol of Pennsylvania State University and William G. Stirling of the University of Keele in Staffordshire, United Kingdom. The investigators propose to conduct a series of neutron scattering investigations of quantum liquids. The collaboration will take advantage of unique neutron scattering instrumentation at ISIS (Rutherford Appleton Laboratory) and the IPNS pulsed neutron sources (Argonne National Laboratory). They will study systems where quantum effects dominate the microscopic properties, as well as the final state effects in liquid helium, the properties of liquid helium mixtures and the effects of restricted geometries on the momentum distribution of liquid helium. Both the U.S. and British investigators bring to this collaboration their experimental expertise and will jointly conduct with their students the measurements and the data analysis. The British instrument has the capabilities for measuring momentum distributions in quantum liquids. This will be complemented by temperature, pressure and concentration measurements on the Argonne spectrometer. Liquid helium is an important element in superconductivity. Quantum effects dominate the behavior in helium's condensed phases and are responsible for its unique properties such as superfluidity. Through studies of momentum distribution, the investigators will gain a unique view and significant insight into the microscopic dynamics of these systems. The proposed joint studies represent detailed investigations of momentum distribution in liquids and will add substantially to our knowledge.