RUI: Ultracryogenic Acoustic and Thermal Evaluation of Metals for Gravity Wave Detectors

Duffy教授将继续对选定的多晶技术材料的机械品质因数（Q）进行超低温研究。 品质因数将在他开发的独特配置中加工的扭转谐振器上测量。 该配置允许在宽Qs（103 - 108）范围和宽温度范围（50 mK-300 K）内进行音频测量（通常为1 kHz）。 由于仅涉及一小块材料（通常为6 cm直径× 6 cm长），因此非常低的温度测量所需的复杂稀释制冷机低温恒温器的操作成本和周转时间保持较低。 这项工作将在美国和国外进行，以支持低温（4K）和超低温（100 mK）谐振质量重力波天线的发展。 将与重力波探测器界保持密切联系。 要研究的材料包括那些最有希望用作高灵敏度引力波探测器的材料。 这需要高Q的材料，其还具有适当的惯性、弹性和热性能。 具体材料，这是本研究的重点，包括爆炸结合铝合金5056和一系列的铜和铝合金。 将评估晶粒尺寸和硬度。 适当的热处理将被开发，这已被发现是如此重要的，以获得高的ultracyogenic Qs的材料研究到目前为止。 将对选定的材料进行超低温热容量和导热性研究。 除了支持重力波天线的发展，结果应该有助于声学损失机制的基本理解。

Professor Duffy will continue ultracryogenic studies of the mechanical quality factor (Q) of selected polycrystalline technical materials. The quality factor will be measured on torsional resonators machined in the unique configuration developed by him. The configuration permits audio frequency measurement (typically at 1 kHz) over a wide range of Qs (103 - 108) and a wide range of temperatures (50mK - 300K). Since only a small piece of material is involved (typically 6 cm diameter by 6 cm long), the cost of operation and the turn-around time of the complex dilution refrigerator cryostat needed for the very low temperature measurements are kept low. The work is to be carried out in support of cryogenic (4K) and ultracryogenic (100 mK) resonant mass gravity wave antenna development both in the United States and abroad. Close contact will be maintained with the gravity-wave- detector community. Materials to be studied include those which offer the most promise for use as gravitational wave detectors of high sensitivity. This requires materials of high Q, which also have appropriate inertial, elastic and thermal properties. Specific materials which are the focus of this study include an explosively bonded aluminum alloy 5056 and a series of copper and aluminum alloys. Grain size and hardness will be evaluated. Appropriate heat treatments will be developed, which have been found to be so essential for obtaining high ultracryogenic Qs in the materials studied to date. Ultralow temperature heat capacity and thermal conductivity studies of selected materials will be carried out. In addition to supporting gravity wave antenna development, the results should contribute to the fundamental understanding of acoustic loss mechanisms.