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HOW TO DETECT A GRAVITATIONAL WAVE: A discussion about the Advanced LIGO Interferometers

Monday, March 28, 2016 - 4:15pm
Spilker 232

Brian T. Lantz

Department of Applied Physics

Stanford University


On September 14th, 2015, the twin detectors of the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) made the first direct measurement of a passing gravitational wave. The signal was generated by the merger of two black holes which were approximately 29 and 36 solar masses. Although the event released about 3 solar masses of energy in a fraction of a second, when the signal reached the earth the distortion from the wave only changed the length of the 4 km long LIGO detectors by about 4e-18 meters. This was considered a large signal, with a signal-to-noise ratio of 24. In this talk, I will describe the remarkable instruments used for this detection, and discuss the plans to move forward so that these detectors can be regular contributors to the field of astronomy.




Dr. Lantz began working on the Laser Interferometer Gravitational-wave Observatory (LIGO) project in 1990 as an undergraduate in Rai Weiss’s lab at MIT. He worked on a variety of LIGO research projects there, and he received his Ph.D. studying shot noise in high-power interferometers, work which held the record for best shot-noise limited phase-sensitivity until the LIGO detectors came on line.


Dr. Lantz then joined the Byer/ Fejer group and moved to Stanford to run the Engineering Test Facility to develop advanced concepts for LIGO. There, he has lead the research for the Advanced LIGO Seismic Isolation system with Prof. Dan DeBra.. Dr. Lantz is a Senior Research Scientist at Stanford, and he is the lead scientist for the seismic isolation systems which support the optics of Advanced LIGO. He is the chair of the LIGO Scientific Collaboration’s Working Group doing research on seismic isolation systems for the next generation of Gravitational Wave detectors, a role which involves precision engineering, servo control, precision measurements, interferometer operation and making big-physics experiments work.


This talk is sponsored by the Department of Applied Physics and by Ginzton Laboratory