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，未来可能会显著提高引力辐射超低温共振质量探测器的探测灵敏度。这项实验引力物理学奖将允许达菲教授继续他的材料Q值和热性质的评估。本研究将重点研究选定的多晶技术材料从50MK到300K的机械品质因数(Q)与温度的关系。L千赫研究的重点将放在50MK到1K的重要温度区域，那里的数据很少。Q值将通过安装在稀释冰箱低温恒温器真空室中的机械谐振器的振动衰减来确定。谐振器将由高纯度的难熔金属和陶瓷材料制造，这些材料表现出大的横截面，用于谐振杆天线对重力波的探测。将制定达到最高低温Qs所需的详细退火程序。将对晶粒度和硬度进行评估。将对选定的材料进行超低温比热容和导热系数研究。除了支持重力波天线的开发外，这些结果还应该有助于从根本上理解超低温下的声损失机制。

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.