Bulletin of the American Physical Society
2010 Annual Meeting of the California-Nevada Section of the APS
Volume 55, Number 12
Friday–Saturday, October 29–30, 2010; Pasadena, California
Session C2: Gravitation and Astrophysics I |
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Chair: Lynn Cominsky, Sonoma State University Room: Building 33 - East Bridge Physics Lecture Hall, Room 201 |
Friday, October 29, 2010 2:00PM - 2:12PM |
C2.00001: Up the Decade! 50 Years of Astronomy and Astrophysics Surveys Virginia Trimble The American astronomical community has just completed its sixth decadal survey, reporting past successes, predicting future advances, and, most important, prioritizing the new, expensive facilities that will be needed to achieve future discoveries. The first such process led to the 1964 Whitford Report, followed by Greenstein, Field, Bahcall, McKee-Taylor, and Blandford. The first five requested 106 identifiable items, about one third of which were achieved with mostly federal funding within 15 years, one third accomplished other ways (private funding, built by other countries, etc.), and the last third never done at all. The Blandford report requests only 7 specific items and so is bound to be either more or less successful than earlier prioritization. Other countries have recently followed in our faltering footsteps: Australia focusing on people and peaceful implementation of changing priorities; Germany emphasizing structural issues; and the UK report bravely indicating which facilities and programs to withdraw from and when, to free up funds for participation in a European Extremely Large Telescope, a Square Kilometer (radio) Array, and other mostly European projects. They even made use of some of my data on production of papers and citation rates for specific existing telescopes! [Preview Abstract] |
Friday, October 29, 2010 2:12PM - 2:24PM |
C2.00002: A high precision mechanical ground rotation sensor Vladimir Dergachev The next generation of gravitational radiation detectors will employ sophisticated isolation systems to attenuate seismic noise and achieve usable sensitivity at frequencies as low as 10 Hz. This requires tight control of displacement at a sub-Hz level, which is difficult due to confusion between tilt and acceleration in linear seismometers and accelerometers. To aid in this effort we are developing a high sensitivity sensor capable of measuring ground tilt at or below 1e-9 rad/sqrt(Hz). We will discuss tiltmeter design and present achieved sensitivity curves. [Preview Abstract] |
Friday, October 29, 2010 2:24PM - 2:36PM |
C2.00003: Tiltmeter Characterization for Seismic Attenuation Systems in Advanced LIGO Amanda O'Toole In order to detect weak gravitational waves, the two detectors making up the Laser Interferometer Gravitational Wave Observatory need to have sensitivity to 1e-22 meters. Our tiltmeter focuses specifically on reducing seismic noise by differentiating between horizontal ground motion and tilt. The sensitivity goal for this balance tiltmeter is 3e-10 radians/sqrt(Hertz) at 10 mHz. Previous tests on the system yielded hysteresis and noise measurements, but more recent advancements include detailed characterization of the knife-edge on which the tiltmeter arm balances as well as improvements to the software control program. After cracks were found in old knife-edge blades, a new cutting scheme was implemented and the new blades photographed. The resulting unbroken test blades were polished and coated with diamond-like carbon to determine whether physical (PVD) or chemical vapor deposition (CVD) was the better choice. In the end, PVD was decided on due to high surface tension in CVD. The final knife-edge is currently being polished and coated. In addition to knife-edge development, new control code was written in order to manage the working point position, viscous damping, and an offset-dependent anti-spring. Further tests advance the tiltmeter sensitivity past its current value of 2e-9 radians/sqrt(Hz) at 1 Hertz, and an interferometric position readout system and vacuum chamber testing are only two of many future advances. [Preview Abstract] |
Friday, October 29, 2010 2:36PM - 2:48PM |
C2.00004: High Precision Tiltmeter Data Acquisition and Control System Caroline Kim The tiltmeter is a high sensitivity ground rotation sensor, built with a 1kg arm balanced on a knife edge. There are various noise present in tiltmeter measurements, and intrinsic noise such as 1/f noise at sub-Hz frequencies has been a big challenge. To aid the tiltmeter development, the tiltmeter position is controlled and read out electronically by its own data acquisition and control system which comprise analog preamplifiers and drivers, data converter electronics, and computer-based controls. The data acquisition system can operate stably over the sensitivity of six orders of magnitude and at the highest frequency range, our sensitivity is 1e-9rad/sqrt(Hz). [Preview Abstract] |
Friday, October 29, 2010 2:48PM - 3:00PM |
C2.00005: Tiltmeter Interferometer Studies Fabian Pena-Arellano, Emanuele Sobacchi, Riccardo DeSalvo, Morgan Shaner The design and characterization of a Michelson interferometer for the readout of the tiltmeter is reported. The maximum angular displacement of the tiltmeter that the interferometer can tolerate is calculated. The noise produced by the transimpedance amplifier of the photodiode is calculated and compared with experimental measurements. The contributions of ground vibrations and laser intensity noise are experimentally identified. A feedback system for locking the interference pattern at a certain intensity was implemented. [Preview Abstract] |
Friday, October 29, 2010 3:00PM - 3:12PM |
C2.00006: Pinpointing Gravitational Wave Sources with LIGO-Australia Linqing Wen, Stan Whitcomb In the next decade, we are expecting to witness two revolutionary developments in gravitational-wave (GW) astronomy: (1) detection of the first gravitational wave, and (2) detection of the electromagnetic counterparts of gravitational-wave sources. A larger network of ground-based GW detectors are essential to achieve the second task. A proposal of placing one copy of the advanced LIGO detector from the US to Western Australia (LIGO-Australia) has been put forward and was formally approved by the NSF. LIGO-Australia will add to the detector network the longest baseline, break the plane degeneracy of the detectors in the northern Hemisphere and therefore improve the network angular resolution dramatically. In this talk, we'll report the status and discuss the scientific benefit of LIGO-Australia. [Preview Abstract] |
Friday, October 29, 2010 3:12PM - 3:24PM |
C2.00007: Seismic investigations for future generations of gravitational-wave detectors Jan Harms, Michael Coughlin Gravity perturbations generated by seismic fields will pose a new noise source in future generations of gravitational-wave detectors. This noise can be estimated based on seismic data. We present a characterization of seismic noise throughout a large part of the US and we discuss the environmental conditions that could impact methods to mitigate noise from gravity perturbations, and which will have to be addressed in the process of a site selection. [Preview Abstract] |
Friday, October 29, 2010 3:24PM - 3:36PM |
C2.00008: Spin precession and the detestability of gravitational waves from inspiraling compact binaries Ajith Parameswaran Inspiraling compact binaries are among the most promising candidate sources for the first detection of gravitational waves. If at least one of the compact objects is rapidly spinning, the general-relativistic spin-orbit and spin-spin coupling cause the binary's orbital plane to precess, producing a visible signature in the emitted gravitational waveforms. These signals are searched over in the data of gravitational-wave detectors using the technique of matched filtering, which involves cross correlating the data with a bank of theoretical templates. A full description of the waveforms requires the use of at least 8 parameters describing the masses and spins of the objects. But performing a search using this 8-parameter template family has a number of difficulties, including the increased false-alarm rate and prohibitive computational cost. In this talk, I propose a post-Newtonian template family described by the two mass parameters and a \textit{single} spin parameter (describing the dominant spin-orbit coupling effect), and demonstrate that the template family is ``effectual'' enough in detecting precessing binaries in the comparable-mass regime. [Preview Abstract] |
Friday, October 29, 2010 3:36PM - 3:48PM |
C2.00009: Gravitational Waves may reveal themselves in Changes in the CMBR Richard Kriske The author has previously suggested that there may be a simple solution that has been overlooked for an explanation for the CMBR. On the earth when one looks at the horizon, distant objects tilt away from the observer, this is well known and the math for this is purely Euclidean. If one imagines a curved three space with a time dimension perpendicular at each point, there is a definite limit at the horizon, where the time dimension makes everything there appear to be at a velocity with increasing acceleration away from every observer standing anywhere on that curved three space. If this curved three space where wavy, just as the ocean has waves there would be a slight change to the horizon, especially if the waves are irregular. If one where to take the CMBR as being a measure of curvature then there should be a slight change to it under unusual circumstances. Other interesting changes should occur in the Lagrange-d'Alembert principle, and close to small intense black holes there should be noticeable changes in the CMBR and path integrals. [Preview Abstract] |
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