24.07.2026: Under the Swiss Alps - Background Characterization of the Bedretto Underground Laboratory

A potential site for a Swiss deep underground laboratory is currently being explored in the Bedretto Tunnel beneath the Gotthard massif in the canton of Ticino. Located 3.5 km from the tunnel entrance, the site lies beneath up to 1500 metres of rock. This natural shielding makes it an exceptional location for experiments that require an environment almost entirely free from interference caused by cosmic radiation.

The results of a comprehensive campaign to characterize the underground environment in the Bedretto tunnel have now beenpublished in European Physics Journal C. The study, which was carried out in close collaboration with the BedrettoLab group at the ETH Zürich, confirms the site's remarkable potential. In particular, the measured flux of cosmic muons is found to be reduced by a factor of one million inside the cavern. This would make the Bedretto Tunnel the second deepest underground laboratory site in Europe.