Cost–benefit analysis for commissioning decisions in GEO 600

Gravitational wave (GW) interferometers are complex instruments, requiring years of commissioning to achieve the required sensitivities for the detection of GWs, of order lesssim10−21 in dimensionless detector strain, in the tens of Hz to several kHz frequency band. Investigations carried out by the GEO 600 detector characterization group have shown that detector characterization techniques are useful when planning for commissioning work. At the time of writing, GEO 600 is the only large scale laser interferometer currently in operation running with a high duty factor, $\sim 70\%$, limited chiefly by the time spent commissioning the detector. The number of observable GW sources scales as the product of the volume of space to which the detector is sensitive and the observation time, so the goal of commissioning is to improve the detector sensitivity with the least possible detector down-time. We demonstrate a method for increasing the number of sources observable by such a detector, by assessing the severity of non-astrophysical noise contaminations to efficiently guide commissioning. This method will be particularly useful in the early stages and during the initial science runs of the aLIGO and adVirgo detectors, as they are brought up to design performance.