A Tilt-Free Seismometer for Advanced Gravitational-Wave Detectors

该项目由LIGO研究计划（物理部）和刺激竞争研究实验计划（EPSCoR）共同资助。对于成熟的引力波物理学领域来说，这是一个激动人心的时刻。先进的LIGO（激光干涉仪引力波天文台）的建设是对最初的LIGO干涉仪的彻底检修，现在已经完成，前几个月的数据已经收集完毕。去年，先进的探测器首次直接探测到引力波，这是一个重大事件，将改变我们对宇宙的理解，标志着引力波天文学一个新领域的开始。爱因斯坦在近100年前就预言了引力波，引力波是由大质量天体（如爆炸的恒星、合并的黑洞或中子星）的运动产生的时空扭曲。然而，引力波对时空的影响是微乎其微的，因此需要设计和建造能够突破精密测量技术极限的探测器。该奖项支持提高高级LIGO低频灵敏度的研究，并增加探测器收集科学质量数据的时间。此外，这个项目将为本科生和研究生提供一个宝贵的培训基地，他们将从不同的学科中发展科学技能，并为他们填补学术界和工业界的职位做好准备。该组织坚定地致力于通过各级外展活动与公众分享该领域的兴奋，特别是在密西西比州的社区。引力波可以通过使用激光测量相距2.5英里（4公里）的镜子之间的无限小的距离变化来探测到。镜子像钟摆一样悬挂着，以隔绝除引力波以外的所有振动。先进的LIGO探测器对镜子之间距离变化的敏感度超过了质子直径的万分之一。尽管如此，在进一步改进干涉仪以提高引力波探测率和扩大可以观测到的天体物理物体的光谱方面仍存在许多挑战。其中一个挑战来自商业地震仪的设计，这些地震仪用于提供镜面的主动隔振。地震仪不能区分地面的水平加速度和倾斜。该合同支持高精度无倾斜地震仪的开发，以改善先进的LIGO地震隔离。该项目包括根据天文台的数据得出无倾斜地震仪的最新要求，设计和建模仪器，构建和测量无倾斜地震仪的性能，并对系统进行理论和实验噪声分析。

This project is jointly funded by the LIGO Research Program (Physics Division) and the Experimental Program to Stimulate Competitive Research (EPSCoR). This is an exciting time for the maturing field of gravitational-wave physics. Construction of Advanced LIGO (the Laser Interferometer Gravitational-wave Observatory), an overhaul of the Initial LIGO interferometers, is now complete and the first couple months of data have been collected. The advanced detectors made last year the first direct detection of gravitational waves, a momentous event that will transform our understanding of the universe and marks the beginning of a new field of gravitational wave astronomy. Predicted by Einstein nearly 100 years ago, gravitational waves are distortions of space-time created by the movements of massive astrophysical objects such as exploding stars and coalescing black holes or neutron stars. The effect of gravitational waves on space-time is minuscule, however, and necessitates the design and construction of detectors that push the limits of precision measurement techniques. This award supports research to improve the Advanced LIGO sensitivity at low frequencies and increase the amount of time the detector is collecting science quality data. In addition, this program will serve as an invaluable training ground for undergraduate and graduate students who will develop scientific skills from a diverse set of disciplines and prepare them to fill positions in academia and industry. The group is strongly committed to sharing the excitement of the field with the public through outreach at all levels, reaching out in particular to the communities in Mississippi.Gravitational waves can be detected by using laser light to measure infinitesimal changes in the distance between mirrors located two-and-a-half miles (4 km) away from one another. The mirrors are suspended as pendulums to isolate them from all vibrations other than the gravitational wave. The Advanced LIGO detectors have achieved a sensitivity to changes in the distance between the mirrors of better than one-ten-thousandth the diameter of a proton. There nonetheless remain many challenges to further improve the interferometers in order to increase the rate of gravitational wave detections and expand the spectrum of astrophysical objects that can be observed. One such challenge arises from the design of the commercial seismometers that are used to provide active vibration isolation of the mirrors. The seismometers cannot distinguish between horizontal acceleration of the ground and tilt of the ground. This award supports the development of a high precision tilt-free seismometer to improve the Advanced LIGO seismic isolation. The project includes deriving updated requirements for a tilt-free seismometer based on data from the observatories, designing and modeling the instrument, constructing and measuring the performance of the tilt-free seismometer and conducting a theoretical and experimental noise analysis of the system.