RUI: Ultralow Temperature Acoustic and Thermal Evaluation of Technical Materials for Gravity Wave Detectors

通过改进探测器材料的选择，可以显著提高引力辐射超低温共振质量探测器的探测灵敏度。这个实验引力物理学奖将允许Duffy教授继续他对材料q值和热性能的评估。本研究将重点研究所选多晶技术材料的机械质量因子(Q)与50 mK至300K温度之间的关系。l kHz研究的重点将放在从50 mK到1 K的重要温度区域，该区域缺乏数据。q值将由安装在稀释制冷机低温恒温器真空室中的机械谐振器的振动衰减来确定。谐振器将由高纯度难熔金属和陶瓷材料制成，这些材料具有较大的横截面，可用于谐振条形天线的重力波探测。详细的退火程序需要达到最高的低温q将开发。将评估晶粒尺寸和硬度。将对选定的材料进行超低温比热容和导热研究。除了支持重力波天线的发展，这些结果应该有助于对超低温下声损失机制的基本理解。

Significant future improvements of the detection sensitivity of ultralow temperature resonant mass detectors of gravitational radiation may be achieved by refined detector material selection. This award in experimental gravitational physics will allow Professor Duffy to continue his evaluation of material Q-values and thermal properties. This research will emphasize studies of the mechanical quality factor (Q) vs. temperature from 50 mK to 300K of selected polycrystalline technical materials. The focus of the l kHz studies will be on the significant temperature region from 50 mK to 1 K, where there is a paucity of data. Q-values will be determined from the vibration decay of a mechanical resonator mounted in the vacuum chamber of a dilution refrigerator cryostat. Resonators will be fabricated from high-purity refractory metals and ceramic materials, which exhibit large cross-sections for gravity-wave detection by resonant bar antennas. Detailed annealing procedures needed to achieve the highest cryogenic Qs will be developed. Grain size and hardness will be evaluated. Ultralow temperature specific heat capacity and thermal conductivity studies will be carried out on selected materials. In addition to supporting gravity wave antenna development, the results should contribute to the fundamental understanding of acoustic loss mechanisms at ultralow temperatures.