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

点击翻译按钮获取中文摘要

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.