It's the specific layout of GEO that gives it an advantage in this case. Its output signal is constructed from the interference between two orthogonal laser beams, that have travelled down its 600m arms and back.
In other similar detectors, the light bounces up and down the arms numerous times before interfering. GEO is currently the largest and most sensitive instrument that/doesn't/ use this technique, and while this makes it less sensitive to gravitational waves, it (somehow*) makes it especially susceptible to this holographic noise.
*not a theorist!
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It's the specific layout of GEO that gives it an advantage in this case. Its output signal is constructed from the interference between two orthogonal laser beams, that have travelled down its 600m arms and back. In other similar detectors, the light bounces up and down the arms numerous times before interfering. GEO is currently the largest and most sensitive instrument that /doesn't/ use this technique, and while this makes it less sensitive to gravitational waves, it (somehow*) makes it especially susceptible to this holographic noise.
*not a theorist!