Symposium on Quantum Fluids and Solids, University Park, PA,June 15-19, 1992

量子流体和固体研讨会，宾夕法尼亚大学公园，1992 年 6 月 15-19 日

• 批准号: 9122374
• 负责人: Paul Sokol
• 金额: $ 0.5万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-03-15 至 1993-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9122374&HistoricalAwards=false
• 关键词: Symposium; Quantum; Fluids; Solids; University

Measurements of the collective excitations of liquid helium have led to a detailed understanding of the microscopic dynamics in both the normal and superfluid phases. Inelastic neutron scattering has proven to be one of the most useful tools in studying these excitations. It is proposed to extend these studies to negative pressures. At low negative pressure the liquid is metastable, allowing measurements to be carried out. At larger negative pressures (around 9 bars), the speed of sound approaches zero and the liquid is no longer stable. Macroscopic samples (one or more cc. in volume) of liquid He at negative pressure will be created using a novel expansion cell. The time structure of a typical short-pulse neutron source will be used to carry out inelastic n scattering measurements in the interval between pressure equilibration and the nucleation of gas bubbles.

液态氦的集体激发的测量已导致对正常和超流体相的微观动力学的详细了解。 事实证明，非弹性中子散射是研究这些激发的最有用的工具之一。 建议将这些研究扩展到负压力。 在低负压下，液体是可稳定的，可以进行测量。 在较大的负压（约9个小节）下，声速接近零，液体不再稳定。 宏观样品（一个或多个CC。在体积中）在负压下将使用新型膨胀细胞创建。 典型的短脉冲中子源的时间结构将用于在压力平衡与气泡成核之间的间隔内进行非弹性N散射测量。