Tunnel configurations and seismic isolation optimization in underground gravitational wave detectors

arXiv (Cornell University)

Abstract

Gravitational wave detectors like the Einstein Telescope will be built a few hundred meters under Earth's surface to reduce both direct seismic and Newtonian noise. Underground facilities must be designed to take full advantage of the shielding properties of the rock mass to maximize the detector's performance. A major issue with the Einstein Telescope design are the corner points, where caverns need to be excavated in stable, low permeability rock to host the sensitive measurement infrastructure. This paper proposes a new topology that moves the top stages of the seismic attenuation chains and Michelson beam re-combination in separate excavations far from the beam-line and equipment induced noise while the test mass mirrors remain in the main tunnels. Distributing the seismic attenuation chain components over multiple tunnel levels allows the use of arbitrarily long seismic attenuation chains that relegate the seismic noise at frequencies completely outside the low-frequency noise budget, thus keeping the door open for future Newtonian noise suppression methods. Separating the input-output and recombination optics of different detectors into separate caverns drastically improves the observatory detection efficiency and allows staged commissioning. The proposed scheme eliminates structural and instrumentation crowding while the reduced sizes of excavations require fewer support measures.

Authors 6

1. Florian Amann Aachen Engineering Geology

   RWTH Aachen University

   Affiliation as printed

   Engineering Geology , RWTH Aachen , Lochnerstrasse 4-20 D-52064 Aachen , Germany

2. F. Badaracco

   UCLouvain · KU Leuven

   Affiliation as printed

   Centre for Cosmology , Particle Physics and Phenomenology , Université catholique de Louvain , Louvain-La-Neuve , B-1348 , Belgium

3. R. DeSalvo

   University of Utah

   Affiliation as printed

   University of Utah , Dep.t of Physics & Astronomy , 115 South 1400 East 0830 Salt-Lake- City UT 84112 ( USA

4. Andrea Paoli

   European Gravitational Observatory

   Affiliation as printed

   EGO , European Gravitational Observatory , Via Edoardo Amaldi , 556021 Cascina (PI Italy)

5. Paolo Ruggi

   European Gravitational Observatory

   Affiliation as printed

   EGO , European Gravitational Observatory , Via Edoardo Amaldi , 556021 Cascina (PI Italy)

6. Stefano Selleri

   Istituto Nazionale di Fisica Nucleare, Sezione di Firenze · University of Florence

   Affiliation as printed

   INFN Sezione di Firenze-Urbino , via G. Sansone , 1 , 50019 , Sesto Fiorentino

   University of Florence , Dept. of Information Engineering ; Via di S. Marta , 3 , 50139 Firenze , ( Italy