Triple Michelson interferometer for a third-generation gravitational wave detector

Abstract

The upcoming European design study 'Einstein gravitational-wave Telescope' represents the first step towards a substantial, international effort for the design of a third-generation interferometric gravitational wave detector. It is generally believed that third-generation instruments might not be installed into existing infrastructures but will provoke a new search for optimal detector sites. Consequently, the detector design could be subject to fewer constraints than the on-going design of the second generation instruments. In particular, it will be prudent to investigate alternatives to the traditional L-shaped Michelson interferometer. In this article, we review an old proposal to use three Michelson interferometers in a triangular configuration. We use this example of a triple Michelson interferometer to clarify the terminology and will put this idea into the context of more recent research on interferometer technologies. Furthermore the benefits of a triangular detector will be used to motivate this design as a good starting point for a more detailed research effort towards a third-generation gravitational wave detector.PACS numbers: 04.80. Nn, 07.60.Ly, 95.75.Kk, 95.55.Ym

Long gravitational-wave transients and associated detection strategies for a network of terrestrial interferometers

“…If, on the other hand, no long GW transients are detected, we expect that some models predicting relatively large strain amplitudes (e.g., [5]) may be ruled out or constrained. Third-generation detectors such as the proposed Einstein Telescope [114] can apply our long GW transient algorithm to probe still fainter sources.…”

Formation of supermassive black holes

“…The Einstein Telescope, a proposed thirdgeneration ground-based gravitational-wave detector will be able to probe gravitational waves in a frequency range reaching down to ∼ 1 Hz (Freise et al, 2009). The frequency range determines the typical masses of coalescing binaries that could be detected by an interferometer; for example, the frequency of gravitational waves emitted from the innermost stable circular orbit of a test particle around a Schwarzschild black hole of mass M is ≈ 4400 Hz(M /M ).…”

Toward a third generation of gravitational wave observatories

“…In particular, triangularshaped detectors have been proposed in the past [86,87] and also the LISA geometry is triangular. A detailed analysis of the benefits and drawbacks of a triangular-shaped third generation gravitational wave observatory is reported in [88] and here we report only the conclusions. Co-located interferometers could be extremely useful to extract additional information from the gravitational wave observation; for example, two L-shaped detectors, forming a 45 • angle, could fully resolve the two polarisation amplitudes of the incoming wave.…”

“…Obviously in an underground site, the realisation of a similar cluster of orthogonal L-shaped detectors is practically impossible, because the huge cost of the infrastructures (several tunnels to accommodate the arms, several caverns to realise the central and end stations), but if the angle between the two arms of each detector is reduced to 60 • , three detectors can be accommodated in a triangular-shaped underground site, minimizing the total length of tunnels, probably the number of caverns and recovering a sensitivity equivalent to two sets of orthogonal L-shaped double detectors, rotated by 45 • (see Fig. B1 of [88]). …”