Study of low-loss materials for mirrors used in the next-generation gravitational wave detectors

下一代引力波探测器反射镜低损耗材料研究

基本信息

批准号：
13440070
负责人：
TSUBONO Kimio
金额：
$ 8.51万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13440070/
关键词：
gravitational wave laser interferometer mirror fused silica low-loss mono-crystalline thermal noise precise measurement

项目摘要

Investigating the mechanical loss of low-loss samples has been an important, but difficult, subject in the field of detecting gravitational-waves. The thermal motion of the internal mode of the mirrors is considered to be one of the fundamental noise sources which limits the sensitivities of gravitational-wave detectors. The amplitude of the thermal motion is proportional to the square root of the mechanical loss of the mirror. Therefore, it is significant to investigate the intrinsic loss of the materials for the mirror to estimate the sensitivity limit of gravitational-wave detectors, and to improve it by finding lower loss materials. However, the loss of low-loss samples is difficult to measure because of the loss due to the support for the measurement.We have developed a method to measure the mechanical loss of cylindrical samples. By using our nodal support technique, the loss due to the support can be excluded. We evaluated separately the intrinsic loss of the material and the loss due to the surface roughness by systematically analyzing the measured losses.Then, we measured the mechanical loss of crystalline anisotropic samples, silicon and sapphire, using a nodal support. Measured quality factor of the silicon sample reached 1.0 x 10^8 at room temperature. The sapphire sample showed lower quality factors, 6.4 x 10^7 at most, which were analytically confirmed to be dominated by surface loss.Also, we systematically measured and compared the mechanical-losses of various kinds of bulk fused silica. Their quality factors widely ranged from 7 x 10^5 to 4 x 10^7, the latter being the highest reported among fused silica mirror substrates. We observed the frequency dependence of Qs. We also found increase in Qs by an annealing.

在检测重力波的领域，研究低损失样品的机械损失一直是一个重要但困难的主题。镜子内部模式的热运动被认为是限制重力波检测器敏感性的基本噪声源之一。热运动的振幅与镜子机械损耗的平方根成正比。因此，重要的是研究镜子的固有损失，以估计重力波检测器的灵敏度极限，并通过找到较低的损失材料来改善它。但是，由于对测量的支持，由于损失损失，低损失样品的损失很难衡量。我们已经开发了一种测量圆柱样品的机械损失的方法。通过使用我们的淋巴结支持技术，可以排除由于支持而造成的损失。我们通过系统地分析了测得的损失，分别评估了材料的内在损失和由于表面粗糙度的损失。在室温下，硅样品的测量质量因子达到1.0 x 10^8。蓝宝石样品显示出较低的质量因子，最多最多为6.4 x 10^7，在分析上证实这是由表面损失主导的。此外，我们系统地测量并比较了各种散装熔融二氧化硅的机械损坏。它们的质量因素的广泛范围从7 x 10^5到4 x 10^7，后者是融合二氧化硅镜底物中报道的最高。我们观察到QS的频率依赖性。我们还发现退火增加了QS。