Violent Events in Superfluid Three-Helium and a Collective Model of Glasses

将对超流氦中的各种现象进行理论研究--在超流氦-3中，液体被猛烈地抛出，脱离热平衡，然后必须恢复。特别是，鉴于Osheroff和Schiffer最近发现伽马射线源是一级A到B相变的有效成核子，计划阐述早先提出的高能电子成核的“烘焙阿拉斯加”机制，并详细预测成核速率与温度和磁场的关系。此外，还计划对低场高过冷A相中的核磁共振行为进行研究，以期获得以前无法获得的液体的微观参数。还建议进一步发展非晶态材料的集体模型，以解释这些材料在低温下的热学和声学性质的显著的定量共性。理论研究将在首席研究人员处于世界领先地位的两个领域进行：(1)将继续研究非晶态材料的模型，以解释在极低温度下不同材料之间的共同性质；(2)将继续研究氦在极低温度下的剧烈行为模型。最近观察到了这种行为，并将根据这些最新和令人兴奋的实验发现，进一步发展早先介绍的理论。

A theoretical study will be carried out on various phenomena in superfluid helium-three in which the liquid is thrown violently out of thermal equilibrium and must then recover. In particular, in light of the recent discovery of Osheroff and Schiffer that a gamma ray scource is an efficient nucleator of the first order A to B transition, it is planned to elaborate the "baked Alaska" mechanism for nucleation of this transition by high energy electrons which was suggested earlier and to make detailed predictions of the dependence of the nucleation rate on temperature and on magnetic field. In addition, studies are planned of the nuclear magnetic resonance behavior in the highly supercooled A phase in low field, with a view to obtaining previously unavailable microscopic parameters of the liquid. It is also proposed to develop further a collective model of amorphous materials for explaining the remarkable quantitative universlaity of the thermal and acoustic properties of these materials at low temperatures. %%% Theoretical research will be conducted in two areas for which the Principal Investigator is the world leader: (1) research will continue on models for amorphous materials to explain the common properties that occur at very low temperatures among diverse materials; (2) work will continue on models for the violent behavior of helium at very low temperatures. This behavior has recently been observed and a theory, introduced earlier, will be further developed in light of these recent and exciting experimental discoveries.