LIGO Document G080621-v1

The Status of Enhanced LIGO

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The Status of Enhanced LIGO

Aidan Brooks for the LSC
LIGO Laboratory, California Institute of Technology, Pasadena CA, 91125, USA

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At the end of September 2007, the Laser Interferometer Gravitational-Wave Observatory (LIGO) achieved its goal of one cumulative year of triple-interferometer-coincidence runtime, known as science run S5. The interferometers operated at their design sensitivity of 2.5 x 10-23 Hz-1/2 equivalent strain noise at 150 Hz. Installation of a major upgrade of the interferometer (Advanced LIGO), designed to reduce the strain noise by an order of magnitude, is scheduled to begin at the start of 2011 and continue through to the end of 2014. The three-year period between the end of S5 and the start of Advanced LIGO affords an opportunity to make some intermediate upgrades to the interferometer and execute another year long science run (S6) with double the sensitivity of S5 the last sensitive observations by LIGO until 2015. This intermediate phase is known as Enhanced LIGO.

The main upgrades to the interferometer are a) a new 35W laser power to reduce the shot noise at higher frequencies, b) an output mode cleaner (OMC) to remove higher order modes that contribute to shot noise and c) a move from RF readout to DC readout. Assorted changes are also being made to auxiliary systems to facilitate these upgrades. Installation across the two LIGO sites is nearing completion and will be followed by approximately six months of commissioning and noise hunting.

I will describe in detail these upgrades and their current commissioning status in Enhanced LIGO. Additionally, I will briefly address the predicted consequences for astrophysical gravitational-wave observations.

Notes and Changes:
v1 is equivalent to 00.

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