Critical Phenomena Near the Superfluid Transition of 4He

液氦超流跃迁的研究4:1)研究含氦气凝胶作为杂质，测量其热膨胀和导热系数。有关浓度和压力依赖性的数据将阐明纯体系和非纯体系中相变之间的关系。2)研究在超流体和正流体速度场存在的情况下，第二声在sf转捩附近的传播，以检验最近一个理论的正确性。量子力学是所有物质行为的基础和主宰。液氦几乎是一种在宏观尺度上表现为量子力学系统的独特物质。这里提出的研究可以促进他们对量子物理学的理解，以及相变和多孔材料的特殊性质。

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.