Advanced LIGO subsystems
are the organizational units of the overall project. Follow the links below to view the mission and progress of each subsystem.

Auxiliary Optics Core Optics
Data Acquisition Data and
Input Optics

Advanced LIGO News

Initial LIGO Exits the Vacuum

[news]Removal of Initial LIGO equipment from vacuum chambers has comprised the principal Advanced LIGO activity early in the construction/installation era that began on October 20, 2010. As of this writing most of the input and output optics and ancillary components are out of their chambers, and a number of the large optics have exited also. Clean room-garbed personnel are now craning out the ton-scale optical tables and passive vibration isolation assemblies. Ultimately each stripped chamber will contain only the horizontal support tubes that carry the weight of a loaded chamber's contents. Advanced LIGO will bring new vibration platforms, optical tables, mirror suspensions, mirrors and sensing equipment into each chamber. Although the overall aLIGO schedule limits the time for de-installation and places a premium on efficiency, crews must work with the utmost of care while extracting decommissioned components. The vacuum envelope must remain free of contamination. Surfaces such as flanges cannot receive even the tiniest of scratches. Many Initial LIGO mirrors will find a second life in LIGO Scientific Collaboration laboratories; the value of these mirrors in research depends on the retention of their quality as they leave the detectors. Components such as optical tables and vibration isolation stacks are heavy and bulky. Their removal requires fastidious attention to detail for the sake of safety.

Gate valves, located at strategic points between vacuum chambers, permit the partitioning of the vacuum system. Operators drop and close a set of gate valves to isolate a group of chambers, then bring the partitioned volume up to atmospheric pressure with clean dry purge air. A 1200-pound chamber door will be craned away to permit access to the interior. Portable clean rooms must shelter any open chambers to provide additional clean protection. Although operations such as door removal and replacement become routine due to repetition, operators must maintain unwavering attention to procedural details at all times. Contamination concerns include not only particulates but water vapor and hydrocarbons which, inside the vacuum, can coat the mirrors and degrade a detector's performance.

Image 1:  Removal of an inner mirror and folding mirror.

Image 2:  A wipe test inside a chamber.

Image 3:  LLO Enhanced LIGO seismic platform departing for MIT.

Image 4:  A BSC vibration isolation stack leaving the chamber.

Image 5:  6000-lb BSC stack close-up.

Image 6:  Removal of the septum along the output beam line.





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