RUI: Acoustic Loss Evaluation of Metals for Ultralow Temperature Gravity Wave Detectors (Physics)

低损耗金属合金和元素的机械质量因子(Q)将在50 mK至4 K的温度和约1 kHz的频率下进行研究。材料的选择将基于预期的适用性，用于超低温韦伯棒重力波探测器。目前最受欢迎的计划探测器材料是铝50-56合金，但替代材料表现出优异的粘合性，导热性和密度。在这些材料上几乎没有超低温q数据，迫切需要评估它们是否适合构建大型探测器。Qs将由安装在稀释冰箱低温恒温器中的小型机械谐振器的自由振动衰减的测量时间常数得到。要研究的材料包括铜合金、铝合金和过渡元素金属。实验研究将强调仔细的冶金特性和系统地消除对测量质量因素的外来贡献。除了支持重力波探测器的发展外，预计该结果将有助于对金属在超低温下的机械损耗机制的基本理解。

The mechanical quality factor (Q) of low-loss metallic alloys and elements will be studied at temperatures from 50 mK to 4 K and at a frequency of about 1 kHz. Material selection will be based on anticipated suitability for use for ultralow temperature Weber-bar gravity wave detectors. The currently favored material for planned detectors is aluminum 50-56 alloy, but alternate materials exhibit superior bondability, thermal conductivity and density. There are practically no ultralow temperature Q-data on these materials, and it is urgently needed to assess their suitability for constructing large-scale detectors. Qs will be obtained from the measured time constants of decay of free vibrations of small mechanical resonators mounted in a dilution refrigerator cryostat. Materials to be investigated include copper alloys, aluminum alloys, and transition element metals. Experimental studies will emphasize careful metallurgical characterization and systematic elimination of extrinsic contributions to measured quality factors. In addition to supporting gravity wave detector development, it is expected that the results will contribute to the fundamental understanding of mechanical loss mechanisms in metals at ultralow temperatures.