Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session S16: Ground Based GW DetectorsLive
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Sponsoring Units: DGRAV Chair: Anamaria Effler, Caltech-LIGO Livingston Observatory |
Monday, April 19, 2021 1:30PM - 1:42PM Live |
S16.00001: LIGO Detector Characterization in the Second and Third Observing Runs Derek Davis The characterization of noise sources and instrumental artifacts of the Advanced LIGO detectors in the second and third observing runs has increased the sensitivity of the instruments, allowing for a higher number of detectable gravitational-wave signals, and provided confirmation of all observed gravitational-wave events. In this talk, I outline how LIGO data differs from the output of an idealized interferometer and how these differences impact searches for and analyses of gravitational-wave signals. I present the methods used to characterize the LIGO detectors and how this information is incorporated into LIGO-Virgo analyses in the second and third observing runs. I detail how inclusion of data quality information has improved analyses of gravitational-waves from both transient and persistent sources. [Preview Abstract] |
Monday, April 19, 2021 1:42PM - 1:54PM Live |
S16.00002: Identifying scattering noise in LIGO using a time-varying filter approach for empirical mode decomposition. Guillermo Valdes, Alessandro Longo, Stefano Bianchi The noise produced by light being scattered from objects limits the gravitational-wave observatories' sensitivity. This noise follows a defined model relative to the object's motion from which light is being scattered. Methods based on the Hilbert-Huang transform, a combination of the empirical mode decomposition (EMD) and the Hilbert spectral analysis (HSA), have been proven to identify these moving scattering objects. In this talk, we present the results of using a time-varying filter approach for EMD to identify scattering objects and their velocity during the third observing run in LIGO. [Preview Abstract] |
Monday, April 19, 2021 1:54PM - 2:06PM Live |
S16.00003: Improving the accuracy of fiducial displacements for gravitational wave detectors. Dripta Bhattacharjee, Yannick Lecoeuche, Sudarshan Karki, Richard Savage Current gravitational-wave detectors employ Photon Calibrators (Pcals) that use the radiation pressure of power-modulated auxiliary laser beams to generate accurate and precise displacement fiducials for absolute length calibration. Accuracy of the fiducials is achieved by propagating laser power calibration from NIST via transfer standards to on-line power sensors monitoring the modulated laser power reflecting from an interferometer mirror. These Pcal-induced displacements are used to calibrate interferometer response functions. Reducing the uncertainty of the Pcal fiducial displacements reduces interferometer calibration uncertainty. Furthermore, referencing the laser power calibration standards for each observatory to a single transfer standard reduces relative calibration errors between the detectors in the network. In this talk, we will discuss the developments and improvements implemented during the recently-completed O3 observing run and some of the ongoing work for the future run to push the Pcal displacement uncertainty below the 0.5{\%} level. [Preview Abstract] |
Monday, April 19, 2021 2:06PM - 2:18PM Live |
S16.00004: Applications of complex modulation for reducing residual amplitude modulation and tuning sidebands Hanyu Chia, David Tanner, Paul Fulda, John Conklin, Guido Mueller Residual amplitude modulation (RAM) is a long-standing issue in optical phase modulation. RAM produces an undesired offset in control signals of optical cavities, such as the ones in Advanced LIGO. Here we present a study of ``complex modulation" (CM) in which we simultaneously modulate the amplitude and the phase of a laser beam. CM provides a feasible approach to reduce concurrent RAMs. Two modulation techniques, single sideband (SSB) modulation and sideband-on-sideband suppression, were experimentally demonstrated by CM as the effective examples for sideband tuning. In order to characterize the electro-optic amplitude modulator (EOAM), a novel scheme to detect parasitic phase modulation (PPM) in an EOAM was built. At least an order of magnitude of RAM reduction and 20-dB suppression of higher-order sidebands were observed. For CM characterization, PPM was measured in real-time by the proposed detection scheme and consequently determined. The experimental results agreed well with CM's core principle of generating designer sidebands. [Preview Abstract] |
Monday, April 19, 2021 2:18PM - 2:30PM Live |
S16.00005: Alignment and mode mismatch sensing for higher-order Hermite-Gauss modes in interferometric gravitational wave detectors Liu Tao, Paul Fulda, Anna Green, Jessica Kelley-Derzon Higher-order Hermite-Gauss (HG) laser modes offer thermal noise advantages over the fundamental mode in interferometric gravitational wave detectors such as Advanced LIGO. These interferometers must however be aligned to a high precision in order to achieve the optimal sensitivity. Preliminary studies have shown that misalignment and mode mismatch tolerances for higher order HG modes are tighter than for the fundamental mode, in the sense that the misalignment and mode mismatch induced power coupling losses scale linearly and quadratically with the mode order respectively. However, we studied by analytical and simulation methods the alignment and mode mismatch sensing for higher-order HG modes in both the traditional wavefront sensing (WFS) schemes and the more recent radio frequency jitter and lens modulation (RFJ/L) schemes. We report higher-order HG modes have stronger alignment and mode mismatch sensing error signals. In particular the RFJ/L schemes show an increase in the sensing gain that exactly matches the decrease in the corresponding tolerance. This potentially eliminates the downside of using higher-order HG modes with respect to their suffering from excessive misalignment and mode-mismatch induced power losses. [Preview Abstract] |
Monday, April 19, 2021 2:30PM - 2:42PM Live |
S16.00006: Debugging Detectors: Numerical Simulations in Support of Commissioning Advanced LIGO and Beyond Anna Green, Paul Fulda, David Tanner Gravitational-wave detectors such as Advanced LIGO, Advanced Virgo and KAGRA are complex optical systems that are carefully designed to be stable and well controlled, however it is inevitable that challenges will be encountered as the detectors are pushed towards their intended sensitivities. It is therefore the job of commissioners to understand and quickly solve problems that affect the controllability or limit the overall sensitivity of a detector. While some issues can be explained using relatively simple analytical models, others require a more nuanced view which includes the full core optical system. The numerical simulation tool FINESSE has been used to support commissioning work at all the detector sites globally, allowing calculation of higher order modes, radiation pressure and quantum behaviours. Here we provide recent examples of commissioning support provided to the LIGO sites as they have modified the detector configuration, increased the circulating power, and introduced squeezed light as we build from Advanced LIGO to A+ and beyond. [Preview Abstract] |
Monday, April 19, 2021 2:42PM - 2:54PM Live |
S16.00007: Application of numerical relativity to the study of thermal noise in GW detectors Tom Wlodarczyk, Harald Pfeiffer, Nils Fischer Thermal noise from mirror-coatings is one factor that limits the sensitivity of ground-based interferometric gravitational wave (GW) detectors such as Advanced LIGO and Virgo. Understanding the properties of thermal noise is therefore important for sensitivity improvements of the detectors. Via the fluctuation-dissipation theorem, thermal noise properties can be studied by solving certain elasticity problems. Remarkably, the resulting partial differential equations are similar to those that arise when solving the Einstein constraint equations for binary black holes. In this talk, I explore the possibility to apply the modern numerical relativity code SpECTRE to the study of thermal noise. In particular, I aim to investigate the influence of the geometry and structure of the mirror coatings on the thermal noise. [Preview Abstract] |
Monday, April 19, 2021 2:54PM - 3:06PM Live |
S16.00008: Reducing noise due to Scattered Light in Advanced LIGO detectors. Siddharth Soni Noise due to scattered light has been a frequent disturbance in the Advanced LIGO gravitational wave detectors, hindering the detection of gravitational waves. The non-stationary scatter noise caused by low-frequency motion can be recognized as arches in the time-frequency plane of the gravitational wave channel. During the third Observing run, we found two different populations of scattering noise. Here I present the methods used to characterize one of the population, investigate its multiple origins, and the technique used to mitigate the noise during the second half of the third Observing run. [Preview Abstract] |
Monday, April 19, 2021 3:06PM - 3:18PM Live |
S16.00009: Boundary Conditions in numerical models of Brownian coating thermal noise of gravitational-wave detector mirrors Samuel Rodriguez Reducing Brownian coating thermal noise is crucial for increasing the sensitivity of ground-based gravitational-wave detectors. One promising idea to decrease thermal noise is to use crystalline coatings, but modeling thermal noise from crystalline coatings is technically challenging. In this talk, I will discuss new numerical calculations that use the fluctuation-dissipation theorem to model Brownian coating thermal noise for crystalline coatings using the fluctuation-dissipation theorem. In this talk, I will present some results that explore the effect of changing the boundary conditions employed on the front, back, and sides of a cylindrical fused-silica mirror substrate with a single-layer crystalline coating. [Preview Abstract] |
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