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

对液氦集体激发的测量使我们对正常相和超流相的微观动力学有了详细的了解。非弹性中子散射已被证明是研究这些激发的最有用的工具之一。有人建议将这些研究扩展到负面压力。在低负压下，液体是亚稳的，因此可以进行测量。在较大的负压下(约9巴)，声速接近零，液体不再稳定。宏观样品(一个或多个毫升。体积)的液体He将使用一种新的膨胀室来产生。典型的短脉冲中子源的时间结构将用于在压力平衡和气泡成核之间的时间间隔内进行非弹性n散射测量。

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.