Tunnel Configurations and Seismic Isolation Optimization in Underground Gravitational Wave Detectors

The Einstein Telescope will be a gravitational wave observatory comprising six nested detectors, three optimized to collect low-frequency signals, and for high frequency. It built few hundred meters under Earth’s surface reduce direct seismic Newtonian noise. A critical issue with the design are corner stations, each hosting at least one sensitive component of all detectors in same hall. Maintenance, commissioning, upgrade activities on detector cause interruptions operation other five, some cases years, thus greatly reducing observational duty cycle. This paper proposes new topology that moves recombination input–output optics Michelson interferometers, top stages attenuation chains noise-inducing equipment separate excavations far from tunnels where test masses reside. separation takes advantage shielding properties rock mass allow continuing detection most even during maintenance others. configuration drastically improves observatory’s event efficiency. In addition, distributing chain components over multiple tunnel levels allows use effectively arbitrarily long relegate noise frequencies farther present budget, keeping door open future upgrades. Mechanical crowding around is eliminated allowing smaller vacuum tanks reduced cross section excavations, which require less support measures.