Site selection

Previous short term studies:

Recent long term measurement, preliminary, Sos Enattos, 480 days:

Geotechnical baseline report (use industry standard): important for tunnel construction (to reduce risks) and gives also info about subsurface for NN estimates
- Water levels, avoid old mines, human activities (cities), future infrastructure plans in region
Realistic sub-surface model to get NN curve (provided by GW scientists)
- Include NN reduction in ET curve
- Requires surface and borehole measurements
Estimate construction costs
Environmental impact study
- Communicate with local entities & society
Need local support: academia, political, funding agencies, industry, infrastructure (airport), local knowledge to build ET, local government
Electromagnetic noise – Schumann resonance (ionosphere): low frequency part of the Earth’s EM field spectrum
Propose 2 or 3 sites to ESFRI
Rules for partner countries and host country (s)
- Host country pays ‘good’ % of the ET project
Involve CERN:
- Use their expertise in vacuum, cryogenics, tunnel construction, financing
- Show that we studied the option to build ET at CERN

Seismic sensors

Calibrate seismic sensors or use industry standard equipment
Frequencies below the cut-off frequency of ET are important because of up-conversion
- Frequency band seismic sensors: 0.1 -100 Hz

Sensitivity curve – low frequency cut-off will be derived from the ET science case
Self-noise: enforce rules based on Ligo/Virgo experience
Relaxation/deformation of the site: prediction if possible, monitoring in any case

Complex preparation
Scientific: Long term seismic characterization, electromagnetic noise
Technical: geological baseline report, environmental impact study, construction costs, …
Social, political: local support, governmental roles, CERN