LIGO project update

David Shoemaker, MIT

Construction is nearing completion at the LIGO Hanford, Washington site, and is in full swing at Livingston, Louisiana. The Hanford site civil construction at the site (buildings, roads, power) is almost complete (door bells are being installed), and the labs and technical spaces are starting to fill. At the Livingston site, the construction of the buildings is largely finished and the forming of the concrete covers for the beam tubes is well underway.

Chicago Bridge and Iron, the company building the LIGO beam tubes (which connect the vertex and ends of the two arms), has completed the fabrication and installation of all 8 km of beam tube at the Hanford site. Those tubes have been tested and are in the process of being formally accepted. The fabrication equipment has been moved to a facility near the Livingston site, and production is well underway. Our contractor for the fabrication of the vacuum chambers and associated equipment which will be in the located in the buildings, Process Systems International, has installed many of the large chambers and associated hardware for the Hanford site; testing is starting. The vacuum chambers for the Livingston site are in construction.

The sites are now home to permanent staff, and the Hanford Observatory has now hosted to several LIGO-related meetings. It is extraordinarily exhilarating to see the dreams of a gravitational wave observatory turned into steel and concrete, and the scale of it all is overwhelming. The next meeting at the Hanford Observatory will be of the LIGO Science Collaboration (or LSC), and is scheduled for March 12-13.

Fabrication of the LIGO Detector components is underway for parts of the seismic isolation system, mirror suspensions, and optical components. A large fraction of the critical test-mass mirrors have been polished and coating will commence shortly. Testing of the first article of one of the isolation system designs will take place early in Spring 98, with production to shortly follow. Electronic designs are being tested in prototype forms, and the first complete stabilized Nd:YAG laser source is being assembled for delivery to the Hanford site this summer.

A test of the phase-sensing system for LIGO is wrapping up in a prototype interferometer at MIT. A record sensitivity of rad Hz has been demonstrated, using the basic laser, suspension, and isolation technology planned for LIGO. This is the last experiment in MIT's beloved Building 20 site, as the lab will move this summer to a new location on the Campus; this enables a reworked test interferometer which will help test second-generation suspension and isolation concepts developed by the LSC.

Our schedule calls for shakedown of the interferometers starting in mid-'99, and operation in 2001. Additional information about LIGO, including our newsletter and information about the LSC, can be accessed through our WWW home page at

Jorge Pullin
Sun Feb 8 20:46:09 EST 1998