'Cat-flap' pendulum offers 7x improvement for grav-wave detectors

It's all about making mirrors less noisy, natch

A University of Western Australia (UWA) boffin who played a major part in Australia's contribution to finding gravitational waves reckons detectors can get a lot more sensitive.

UWA Professor David Blair, who discussed how quantum noise can interfere with gravitational wave detection with Vulture South in 2011, has supervised a PhD student's experiment that claims a seven-fold improvement in sensitivity.

In the university's canned statement, Blair says “Currently the detectors can only detect huge tsunami-like waves, but with the new technology we would be able to extend that range about seven times.”

As readers will remember, the LIGO detectors that discovered gravitational waves work by splitting the light from a laser, and sending the two beams down 4km tunnels.

Mirrors (which Blair contributed to developing) send the signals back to a detector – the interferometer – that does the heavy lifting of detecting the effects of the gravitational wave. If a wave has passed through the Earth, there will be a tiny ripple that shows up as interference in the light.

Given the extreme sensitivity of LIGO – it can detect movements 10,000 times smaller than a proton – it's hard for mere mortals to imagine how it could get even more sensitive, but that's what Blair and his team are working on, by trying to make the mirrors more immune to noise.

Their work is described in Section 6.4 of this pre-publication over at Arxiv, and it's based on a tiny version of an ancient device, the pendulum.

The “cat-flap pendulums”, the university says, are designed to be fitted to existing detectors. Less than a millimetre in size, the devices – more formally named a “membrane suspended pendulum” – is a mirror design that should reduce the noise the detector experiences.

A student of Blair's, Jiayi Qin, modelled the concept, and the university is now building the devices with a million-dollar ion beam etcher. ®

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