Giant Neutrino Detectors Go Up in an Old Gold Mine to Ask Why Anything Exists

Construction of one of the world’s most ambitious physics experiments is due to begin Monday inside a former gold mine in Lead, South Dakota, according to The Guardian. The Deep Underground Neutrino Experiment, known as Dune, will use four giant detectors in caverns a mile underground to study ghostly particles called neutrinos.

Scientists hope the data will help explain why the universe is made of matter rather than antimatter, a puzzle the Guardian summed up as the question of why anything is here at all.

From gold to neutrinos: how the Homestake mine changed purpose

• 1960s: Physicist Ray Davis built a detector from a 100,000-gallon tank of dry-cleaning fluid deep in the mine. Shielded by rock, it became the first to record neutrinos from the sun, which turned chlorine atoms in the fluid into argon.
• 2001: The mine closed and later became a dedicated underground laboratory, the Sanford Underground Research Facility. It already hosts the Lux-Zeplin experiment, which last month reported the first potential detection of dark matter.
• Monday: Engineers begin assembling the Dune detectors.
• About three years later: Assembly of the detectors should be complete, with another year needed to fill them with liquid argon.

What Dune will actually do

Neutrinos are the most abundant matter particles in the universe, outnumbered only by photons. They are produced in nuclear reactions such as those in the sun, in radioactive decay and in particle accelerators. About a trillion pass through your body each second without being noticed.

Dune will study a beam of neutrinos sent from Fermilab, a particle physics facility in Illinois, through 800 miles (1,300km) of rock. Most will pass straight through. Now and then one will strike an argon atom, producing a flicker of light and a pulse of electric charge that reveals details about the particle. The detectors will also study neutrinos arriving from space, which carry information about exploding stars and the formation of black holes.

Neutrinos come in three varieties with tiny but different masses, and they switch between varieties as they travel, a process called oscillation. Dr Kate Shaw, a particle physicist on Dune from the University of Sussex, compared it to being thrown an apple that turns into a banana. She said neutrinos do not yet make sense and could open a door to new physics.

Two questions are central. Which neutrino is lightest and which heaviest, an answer that could point to new forces of nature? And do neutrinos behave differently from their antimatter twins, antineutrinos, in a way that could explain the dominance of matter?

The scale of the build

The detectors will use more than 4,000 tonnes of steel, stand up to five stories high and hold a combined 70,000 tonnes of liquid argon chilled to -200C. David Newbold of the UK’s Science and Technology Facilities Council, a Dune spokesperson, called the project heavy-duty engineering, “like building a ship underground.”

The UK is the largest international partner in the US-led project. It is making core detector components, computing systems to reconstruct events in the detectors, and the graphite target used to generate neutrinos at Fermilab.

What this means for the people of Lead

For the town, the project continues a story that began with mining. Robin Lucero, Lead’s city administrator, said the area has gone from mining the Earth to helping scientists explore the universe. She said world-class science brings new opportunities, new people and new possibilities for local businesses, especially for young people.

Newbold said he expects a golden era for neutrino research, with much more discovery to come.

Around Prague, based on reporting by The Guardian