Collaborative Research: LSC Center for Coatings Research

合作研究：LSC 涂料研究中心

• 批准号: 2011723
• 负责人: Stefan Ballmer
• 金额: $ 54.18万
• 依托单位: Syracuse University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-15 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2011723&HistoricalAwards=false
• 关键词: Collaborative; Research; LSC; Center; Coatings

The detections of gravitational waves from coalescing black holes in 2015 launched the field of gravitational wave astronomy. The NSF-funded “A+” upgrade to Advanced LIGO is designed to achieve an order of magnitude increase in detection rate for black hole coalescences, and enable detection of fainter objects like binary neutron stars, greatly increasing their value for multi-messenger astronomy. The A+ upgrade and all 3rd generation detector designs depend on the development of mirrors with low coating thermal noise. The coating thermal noise is reduced, primarily, by lowering the mechanical (elastic) loss of the mirror materials. The core research focus of the LIGO Scientific Collaboration (LSC) Center for Coatings Research (CCR) is the development of mirror coatings with low mechanical and optical losses for use in A+ and 3rd generation detectors. The research mission of the CCR includes: understanding and reducing mechanical loss in amorphous metal-oxides, the most widely-used materials in mirror coatings; and developing and testing crystalline (AlGaAs) coatings, which have demonstrated low losses for small mirrors. On a longer time-scale, the CCR is developing mirrors compatible with the proposed 3G detectors’ cryogenic operation. The residual noise visible in the time-domain gravitational waveforms of black hole mergers first recorded by Advanced LIGO is mostly due to quantum noise of the light and thermal noise due to the mirror coatings. Since that first discovery much progress has been made in reducing quantum noise and the coupling from seismic, scatter and jitter noise, leaving coating thermal noise as the dominant barrier limiting gravitational-wave astronomy in the most sensitive observation band. Reducing this noise source for future generations of detectors requires reducing the mechanical dissipation in the mirror coatings on the test masses, and forms the main goal of the CCR. The CCR combines groups working on computational modeling, coating deposition, and characterization of atomic structure and macroscopic material properties. These components are often performed by four diverse communities that work in relative isolation from each other. The strength of the CCR and its promise of accelerating discoveries arises from close integration of these communities focused on a unified research goal. In its first two years of operation, research in the CCR has identified different structural motifs associated with room-temperature vs cryogenic mechanical losses, which led to synthesis of germania (GeO2) films giving rise to the lowest-loss amorphous oxide film other than silica. Going forward, this structural guide will serve as a paradigm informing the development of high-refractive index amorphous coatings with lower elastic loss. In addition, thermo-optically-optimized AlGaAs crystalline coatings have demonstrated a coating thermal noise well below the requirements for A+, and the CCR has generated a development schedule to scale up these coatings to LIGO mirror sizes and will continue investigations into these materials. Other research paths include: exploring deposition techniques to produce “ultrastable glasses” using amorphous metal-oxides; and stabilizing amorphous coatings against crystallization in order to allow elastic loss reduction via high temperature annealing either with nano-layering or with different doping materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

2015年对黑洞聚并引力波的探测开启了引力波天文学领域的先河，由NSF资助的Advanced LIGO“A+”升级旨在实现黑洞聚并的探测率提高一个数量级，并实现探测。 A+ 升级和所有第三代探测器设计都依赖于低反射镜的开发。涂层热噪声主要是通过降低反射镜材料的机械（弹性）损耗来降低的，LIGO 科学合作中心（LSC）涂层研究中心（CCR）的核心研究重点是反射镜的开发。用于 A+ 和第三代探测器的低机械和光学损耗涂层 CCR 的研究任务包括：了解和减少非晶金属氧化物（镜面涂层中使用最广泛的材料）的机械损耗；晶体（AlGaAs）涂层，在较长的时间尺度上证明了小反射镜的低损耗，CCR 正在开发与拟议的 3G 探测器低温操作兼容的反射镜，在黑色时域引力波形中可见残余噪声。先进 LIGO 首次记录的空穴合并主要是由于镜面涂层引起的光量子噪声和热噪声，自从首次发现以来，在减少量子噪声以及地震、散射和辐射耦合方面取得了很大进展。抖动噪声，使涂层热噪声成为限制引力波天文学在最敏感观测波段的主要障碍，为下一代探测器减少这种噪声源需要减少测试质量上镜面涂层的机械耗散，并形成主要障碍。 CCR 的目标是由致力于计算建模、涂层沉积以及原子结构和宏观材料特性表征的各个小组组成，这些小组通常由四个相互独立的不同团体执行。 CCR 及其加速发现的承诺源于这些社区的密切整合，这些社区专注于统一的研究目标。在运行的头两年中，CCR 的研究已经确定了与室温和低温机械损失相关的不同结构主题，这导致了 CCR 的发展。展望未来，该结构指南将作为高折射率非晶态发展的范例。此外，热光优化的 AlGaAs 晶体涂层的涂层热噪声远低于 A+ 的要求，CCR 已制定了将这些涂层扩大到 LIGO 反射镜尺寸的开发计划，并将继续进行。对这些材料的研究包括：探索使用非晶金属氧化物生产“超稳定玻璃”的沉积技术；以及稳定非晶涂层以防止结晶，以便通过高温退火减少弹性损失。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。