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

将对超流体氦- 3中的各种现象进行理论研究，在这些现象中，液体被猛烈地抛出热平衡，然后必须恢复。特别是，根据Osheroff和Schiffer最近的发现，伽马射线源是一阶a到B跃迁的有效成核体，计划详细阐述先前提出的高能电子使这种跃迁成核的“烤阿拉斯加”机制，并详细预测成核速率对温度和磁场的依赖关系。此外，还计划对低场下高度过冷A相的核磁共振行为进行研究，以期获得以前无法获得的液体微观参数。本文还提出了进一步发展非晶材料的集体模型，以解释这些材料在低温下的热学和声学特性的显著定量普遍性。理论研究将在两个领域进行，其中首席研究员是世界领先的：(1)将继续研究非晶材料的模型，以解释各种材料在极低温度下发生的共同特性；(2)将继续研究氦在极低温下剧烈行为的模型。这种行为是最近观察到的，早先提出的一个理论，将根据最近这些令人兴奋的实验发现进一步发展。

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.