LIGO magazine will regularly provide news from international gravitational wave research
The articles featured in the first issue include:
The evolution of Advanced LIGO
Starting in late 2007 and ending in 2015, the Advanced LIGO (aLIGO) Project will deliver detectors which will have locked for several hours and will be capable, after post-Project tuning, of a factor of 10 improvement in sensitivity over initial LIGO. This brings an increase in the volume of space that can be searched of a factor of 1000, and with an increase also in the frequency range down to 10 Hz, detections of the standard candle of binary neutron stars are expected weekly to monthly. Three interferometers are built, with the current plan to place one of the three in India to extend the baseline of the LIGO – and worldwide – network of detectors. This note gives an overview of the evolution of Advanced LIGO from the first ideas to the projected completion.
Monolithic Suspensions: From the Lab to Advanced LIGO
At the heart of each Advanced LIGO (aLIGO) detector are four large mirrors – test masses – made of fused silica, two in each arm of the interferometer. To look for gravitational waves we measure and compare the relative separation of the test masses in each arm. Each of these 40 kg mirrors is delicately suspended from another silica mass by four silica fibers – a considerable change from the design used in Initial LIGO, where the mirrors were each suspended by a single loop of steel wire. The new construction is known as a “monolithic” suspension since the suspension fibers, the mirrors, and the bonds between them are a single piece of a single material.
Why the change? In this article we aim to answer that question and to describe how the aLIGO monolithic suspension design was developed from early lab experiments at Glasgow and elsewhere to the final product currently being installed.
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