Bulletin of the American Physical Society
APS April Meeting 2016
Volume 61, Number 6
Saturday–Tuesday, April 16–19, 2016; Salt Lake City, Utah
Session H14: Ground Based Gravitational Wave Detectors |
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Sponsoring Units: GGR Chair: Stefan Ballmer, Syracuse University Room: 251AB |
Sunday, April 17, 2016 8:30AM - 8:42AM |
H14.00001: Noise Performance of the Advanced LIGO Detectors Evan Hall Advanced LIGO has completed a four-month search for gravitational wave events using two 4-km laser interferometers separated by a 3000 km baseline. These instruments can sense spacetime strain to better than $10^{-23}/\mathrm{Hz}^{1/2}$ in their most sensitive frequency band (80 Hz to 400 Hz). The interferometers' sensitivity is limited by a variety of noise sources, including thermal fluctuations of the test masses and their suspensions, quantum and classical fluctuations of the laser light used to interrogate the test masses, residual environmental disturbances, and noises arising from the sensing and control of the interferometers' length and angular degrees of freedom. We present a budget of these noise sources as they appeared during the first observing run, and discuss ongoing improvements as we look forward to Advanced LIGO achieving full design sensitivity. [Preview Abstract] |
Sunday, April 17, 2016 8:42AM - 8:54AM |
H14.00002: Calibration of the Advanced LIGO Detectors During the First Observational Run Jeffrey Kissel The Advanced LIGO detectors have completed their first observational run, between Sep 2015 and Jan 2016, at unprecedented sensitivity. Establishing the accuracy and precision in the calibration of these second-generation detectors has been challenging given the new complexities in the interferometer control system. In this talk we describe these challenges, outline new methods we've employed to meet those challenges, and discuss the resulting magnitude and phase uncertainty in the calibrated output of the detectors. [Preview Abstract] |
Sunday, April 17, 2016 8:54AM - 9:06AM |
H14.00003: Calibration of the Advanced LIGO detectors using radiation pressure Shivaraj Kandhasamy Calibration of gravitational-wave detectors to high accuracy and precision is crucial for extracting astrophysical parameters from gravitational-wave signals. A precise calibration will also aid in studying long term instrumental effects. For interferometric gravitational-wave detectors, techniques based on radiation pressure are promising candidates for achieving absolute calibration uncertainties below 5\%. These methods use auxiliary, power-modulated lasers to produce known displacements of test masses which are then used to calibrate the outputs of the detectors. Because they are external to the operation of the detectors, they are also ideal for injecting simulated gravitational-wave signals to test and characterize analysis pipelines. In this talk we describe the set up that was used during first observing run of Advanced LIGO and discuss its impact on the calibration. [Preview Abstract] |
Sunday, April 17, 2016 9:06AM - 9:18AM |
H14.00004: Hunting for MHz gravitational waves with the Fermilab Holometer Brittany Kamai The highest frequency end of the gravitational wave spectrum remains poorly constrained. Cosmic strings and primordial black holes are potential gravitational waves candidates that could radiate at MHz frequencies. The existence of nearby sources can be tested using the Fermilab Holometer, two nested 40 meter Michelson interferometers. This instrument can achieve strain sensitivity better than $10^-20/rt.Hz$ within the 1-10 MHz frequency band. The Holometer is fully operational and has taken long observational campaigns acquiring 100s of hours of science quality data. I will present results of a search for narrow-lined sources and constraints on the stochastic background in the MHz band. [Preview Abstract] |
Sunday, April 17, 2016 9:18AM - 9:30AM |
H14.00005: The input optics of Advanced LIGO D.B. Tanner, M.A. Arain, G. Ciani, D. Feldbaum, P. Fulda, J. Gleason, R. Goetz, M. Heintze, R.M. Martin, C.L. Mueller, L.F. Williams, G. Mueller, V. Quetschke, W.Z. Korth, D.H. Reitze, R.T. DeRosa, A. Effler, K. Kokeyama, V.V. Frolov, A. Mullavey, J. Poeld The Input Optics (IO) of advanced LIGO will be described. The IO consists of all the optics between the laser and the power recycling mirror. The scope of the IO includes the following hardware: phase modulators, power control, input mode cleaner, an in-vacuum Faraday isolator, and mode matching telescopes. The IO group has developed and characterized RTP-based phase modulators capable of operation at 180 W cw input power. In addition, the Faraday isolator is compensated for depolarization and thermal lensing effects up to the same power and is capable of achieving greater than 40 dB isolation. [Preview Abstract] |
Sunday, April 17, 2016 9:30AM - 9:42AM |
H14.00006: RF jitter modulation alignment sensing for interferometric gravitational wave detectors. P. Fulda, D. Voss, L. Ortega, N. Foster, G. Mueller, D. B. Tanner Correct alignment of the optics is crucial for optimizing the sensitivity of interferometric gravitational wave detectors. Alignment sensing and control is therefore an important subsystem in these instruments. With many degrees of freedom to sense and control, however, the problem of generating well separated alignment error signals is a challenging one. We will present an alternative method for generating interferometric alignment control signals that takes advantage of the high-frequency alignment dither that can be achieved with electro-optic beam deflectors. This method may be useful in conjunction with currently implemented methods to simplify the alignment sensing and control scheme in Advanced LIGO. [Preview Abstract] |
Sunday, April 17, 2016 9:42AM - 9:54AM |
H14.00007: A low loss Faraday isolator for squeezed vacuum injection in Advanced LIGO Ryan Goetz, David Tanner, Guido Mueller Using conventional interferometry, the strain sensitivity of Advanced LIGO is limited by a quantum noise floor known as the standard quantum limit (SQL). Injecting squeezed vacuum states into the output port of the interferometer allows for detector sensitivities below the SQL at frequencies within a band of observational interest. The effectiveness of squeezing in reducing quantum noise is strongly dependent upon the optical loss in the squeezed path. Thus, to combine the squeezed vacuum state with the interferometer output we require a Faraday isolator with both high power-throughput efficiency and high isolation ratio. A prototype isolator is currently being developed, and we will discuss the design goals and current status. [Preview Abstract] |
Sunday, April 17, 2016 9:54AM - 10:06AM |
H14.00008: CryoTHOR: measuring thermal noise in optical coatings Giacomo Ciani, Johannes Eichholz, Michael Hartman, Guido Mueller Brownian thermal noise in the optical coatings of the test mirrors is expected to be one of dominant noise sources in the most sensitive frequency band of the Advanced LIGO detectors, from a few tens to a few hundreds Hz. Together with thermo-optic noise, it is also envisioned to be one of the main obstacles to improving the sensitivity of future gravitational wave observatories, including cryogenic ones. Many groups are currently engaged in the development of advanced coatings designs with reduced noise. Expected performances of such coatings are usually calculated using independent measurements of material properties which enters in the modeling of thermal noise. However, these properties are often highly dependent on the material history and specific geometric arrangement, and their measured values affected by relatively big uncertainties. Furthermore, their temperature dependence is not always well studied. A direct measurement of the thermal noise over a wide range of temperatures is clearly the preferred way of assessing a coating design viability. We report on the design, performance and latest results of cryoTHOR, an experiment developed for the direct measurements of coating thermal noise over the entire LIGO frequency band, both at room and cryogenic temperatures. [Preview Abstract] |
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