Question: What America physicist was a spokesperson at the LIGO Scientific Collaboration?

Context paragraphs:
Alessandra Buonanno: Alessandra Buonanno is a theoretical physicist working in gravitational-wave physics and cosmology.  She is a director at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Potsdam, Germany, leading the "Astrophysical and Cosmological Relativity" division.  She holds a College Park professorship at the University of Maryland, College Park in College Park, Maryland, and is a meber of the LIGO Scientific Collaboration.

Rainer Weiss: Rainer "Rai" Weiss ( ; ] ; born September 29, 1932) is an American physicist, known for his contributions in gravitational physics and astrophysics.  He is a professor of physics emeritus at MIT.  He is best known for inventing the laser interferometric technique which is the basic operation of LIGO.  Rainer Weiss was Chair of the COBE Science Working Group.

Ibercivis: Ibercivis is a distributed computing platform which allows internet users to participate in scientific research by donating unused computer cycles to run scientific simulations and other tasks.  The project, which became operational in 2008, is a scientific collaboration between the Portuguese and Spanish governments, but it is open to the general public and scientific community, both within and beyond the Iberian Peninsula.  The project's name is a portmanteau of "Iberia" and the Latin word "civis", meaning "citizen".

Scientific collaboration network: Scientific collaboration network is a social network where nodes are scientists and links are co-authorships as the latter is one of the most well documented forms of scientific collaboration.  It is an undirected, scale-free network where the degree distribution follows a power law with an exponential cutoff – most authors are sparsely connected while a few authors are intensively connected.  The network has an assortative nature – hubs tend to link to other hubs and low-degree nodes tend to link to low-degree nodes.  Assortativity is not structural, meaning that it is not a consequence of the degree distribution, but it is generated by some process that governs the network’s evolution.

Bruce Allen (physicist): Bruce Allen (born May 11, 1959) is an American physicist and director of the Max Planck Institute for Gravitational Physics in Hannover Germany and leader of the Einstein@Home project for the LIGO Scientific Collaboration.  He is also a physics professor at the University of Wisconsin–Milwaukee.

Bernard F. Schutz: Bernard F. Schutz (born August 11, 1946, in Paterson, New Jersey) is an American physicist.  His research is on Einstein's theory of general relativity, more concretely on the physics of gravitational waves.  He is one of the directors and head of the astrophysics group at the Max Planck Institute for Gravitational Physics in Potsdam, Germany.  He is principal investigator in charge of data analysis for the GEO600 collaboration (which, in turn, is part of the LIGO Scientific Collaboration, the largest concerted effort to directly detect gravitational waves).  Schutz is also a member of the science team coordinating the planning and development for the space-borne gravitational wave detector LISA (Laser Interferometer Space Antenna), and he was instrumental in the foundation of the electronic, open access review journal "Living Reviews in Relativity".

Gabriela González: Gabriela González, (born 24 February 1965 in Cordoba, Argentina ) is a professor of physics and astronomy at the Louisiana State University and was the spokesperson for the LIGO Scientific Collaboration from March 2011 until March 2017.  She has published several papers on Brownian motion as a limit to the sensitivity of gravitational-wave detectors, and has an interest in data analysis for gravitational-wave astronomy.

Advanced LIGO Documentary Project: The Advanced LIGO Documentary Project is a collaboration formed in the summer of 2015 among Caltech, the Massachusetts Institute of Technology and Director Les Guthman to document the Advanced LIGO search for gravitational waves, both to videotape a longitudinal record of the project for history and to make a documentary of the LIGO project's then-expected detection of the first gravitational waves.

LIGO Scientific Collaboration: The LIGO Scientific Collaboration (LSC) is a scientific collaboration of international physics institutes and research groups dedicated to the search for gravitational waves.  The LSC was established in 1997, under the leadership of Barry Barish.  Its mission is to ensure equal scientific opportunity for individual participants and institutions by organizing research, publications, and all other scientific activities, and it includes scientists from both LIGO Laboratory and collaborating institutions.  Barish appointed Rainer Weiss as the first spokesperson.

David Reitze: David Reitze (born January 6, 1961 in Washington, Pennsylvania) is an American laser physicist who is Professor of Physics at the University of Florida and served as the scientific spokesman of the Laser Interferometer Gravitational-Wave Observatory (LIGO) experiment in 2007-2011.  In August 2011, he took a leave of absence from the University of Florida to be the Executive Director of LIGO, stationed at the California Institute of Technology, Pasadena, California.  He obtained his BA in 1983 from Northwestern University, his PhD in Physics from the University of Texas at Austin in 1990, and had positions at Bell Communications Research and Lawrence Livermore National Laboratory, before taking his faculty position at the University of Florida.  He is a Fellow of the American Physical Society and The Optical Society.

Supporting paragraphs: LIGO Scientific Collaboration Rainer Weiss
Answer: Rainer "Rai" Weiss