Critical Phenomena Near the Superfluid Transition of 4He

研究液氦中的超流体(SF)转变4：1)研究作为杂质的氦气凝胶，测量热膨胀和导热系数。关于浓度和压力依赖关系的数据将阐明纯和不纯体系中相变之间的关系。2)研究在超流和正常流体速度场存在下SF相变附近的二次声传播，以验证最近的一个理论的正确性。量子力学是所有物质行为的基础和主宰。液氦几乎是独一无二的，因为它是一种在宏观尺度上表现为量子力学系统的物质。这里提出的研究有望促进他们对量子物理、相变和多孔材料的特殊性质的理解。

Investigations of the superfluid (sf) transition in liquid helium 4: 1) Study helium containing aerogels as an impurity, measuring the thermal expansion and thermal conductivity. Data on the concentration and pressure dependences will illuminate the relationship between the phase transitions in the pure and impure systems. 2) Study the propagation of second sound near the sf transition in the presence of superfluid and normal-fluid velocity fields, to test the correctness of a recent theory. %%% Quantum mechanics underlies and governs the behavior of all matter. Liquid helium is almost unique in being a substance which behaves as a quantum mechanical system on a macroscopic scale. Studies such as are here proposed can be expected to advance their understanding of quantum physics, as well as phase transitions and the special properties of porous materials.