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South Africa digs deep for underground physics lab

Image: Richard Newman

Researchers hope to study dark matter and neutrinos from within South African mountain range

The Department of Science and Innovation in South Africa has approved seed funding worth R5 million (US$270,000) to design Africa’s first underground laboratory to study dark matter and neutrinos.

The Paarl Africa Underground Laboratory (Paul) project was launched during a symposium held in Stellenbosch from 14 to 18 January, which included a visit to the proposed site in the Du Toitskloof Mountains between Paarl and Worcester in the Western Cape province.

The project would make use of existing road tunnels that cut through the mountain range. Built in the 1980s, the tunnels shave up to half an hour and 11 kilometres off the travel time and distance between Cape Town and Johannesburg on the N1 highway. Two parallel tunnels were built; one is not used (see picture) but may come into use as part of an imminent upgrade.

The proposal envisages a lab 800 metres underground, to be built in an existing service tunnel. Its floorspace would measure 16 by 40 metres, with a roof height of 16 metres. “For comparison, an Olympic-size swimming pool has a length of 50 metres and a width of 25 metres,” says Richard Newman from Stellenbosch University’s physics department, who is involved in the project.

Once built, the proposed laboratory would search for cosmic particles that are used to study dark matter, which makes up 85 per cent of the universe’s mass. Measurements will start using a muon detector borrowed from the Institute of Physics of the Two Infinities (IP2I) in Lyon, France, to inform the design process. The facility would also study neutrinos in radioactive-free environments.

Paul would be the second laboratory of its kind in the Southern Hemisphere, after Australia’s Stawell underground physics laboratory unveiled in August 2022.

Lots left to do

Newman says the Paul project received R5m from the DSI to carry out a feasibility study for the project. The University of Stellenbosch contributed R130,000 of seed funding for the design of the project.

“The results of the feasibility study will be shared with the DSI and Department of Transport, and we will then request a go-ahead from the government to proceed to do a detailed engineering design,” Newman told Research Professional News. He added that the feasibility study would identify any technical or operational hurdles standing in the way of the project.

There is a long road ahead, Lerothodi Leeuw, professor of physics and astronomy at the University of Western Cape and also part of the Paul project, told Research Professional News. “Only seed funding has been approved for the design. Permission to build needs many things for approval,” he said.

“We will need funding from the government to establish Paul,” Newman said. He added that the project will also need buy-in from South Africa’s national road agency, Sanral, to integrate the lab’s construction into the agency’s planned upgrade project for the tunnel system, due to start later this year. “There is still a lot to do on the Paul side before then,” he said.