Researchers target Porta Alpina shaft for dark matter experiment

Researchers plan to turn the Porta Alpina shaft near Sedrun into a research station for quantum physics instead of using it for tourism, Swiss public broadcaster SRF reported.

The project would install an atom interferometer, a specialised measuring device that could help establish whether dark matter exists. Scientists have not yet directly detected dark matter, but believe it exists because its gravity affects the universe.

The 800-metre shaft, along with access tunnels and emergency stations, was built during construction of the Gotthard Base Tunnel. It was intended to support a lift carrying visitors from an underground station to Sedrun, but the 50 million franc tourism project failed because of financing and scheduling problems.

An international research group is now assessing the facility. Swiss participants include CERN, the University of Zurich and the University of Applied Sciences of the Grisons. Seismic and electrical measurements carried out last year led project leader Lucas Lombriser, a professor at the University of Applied Sciences of the Grisons, to describe Sedrun as the best location in Europe.

The Gotthard Base Tunnel below the shaft carried around 32,000 trains during the measurement period. Lombriser said researchers detected the trains but that they did not affect the measurements. They did, however, register waves from the Atlantic and the Mediterranean, hundreds of kilometres away.

The location has not yet been chosen. The international project is estimated to cost around 500 million francs, with several countries and institutions expected to contribute. Construction could begin in 2030, with the facility scheduled to enter operation in 2035.