Secrets of the universe may lie down an old gold mine
Brilliant minds from around world go to S. D.
The universe as we know it shouldn’t exist. Unlocking the reasons why may depend on once again striking gold in a mine buried a mile underground in rural South Dakota.
The largest U. S.- based particle physics experiment ever is now under construction in the old mine in Lead, S. D., breathing new life into the small town more than 140 years after the Black Hills gold rush drove its founding.
The international collaboration involving 1,000 scientists from more than 30 countries aims to answer the question: Are mysterious particles called neutrinos the reason we are here?
Scientists believe equal parts of matter and antimatter should have been created during the formation of the universe. But that didn’t happen, and no one knows why. Instead, the visible universe is dominated by matter. Neutrinos may be the reason why — physicists just need a bigger, well, everything to find out.
Once complete, the Deep Underground Neutrino Experiment will beam the particles 800 miles through the earth from Fermi National Accelerator Laboratory outside Chicago to Lead’s Sanford Underground Research Facility.
Sanford Underground Research Facility, which opened in 2012 after it repurposed the gold mine for scientific research, has run experiments involving neutrinos and dark matter, but nothing even close to this scale.
To embark on its grand experiment, Sanford must first expand its footprint by carving out the Long- Baseline Neutrino Facility amid tunnels that once housed the deepest and most productive gold mine in the Western Hemisphere.
Over the next 10 years, workers will remove more than 870,000 tons of rock and install a four- story high, 70,000- ton neutrino detector, while the lab’s Illinois counterpart also undergoes significant renovations.
The project will cost more than $ 1 billion, but scientists hope the payoff from about 12 million neutrinos per second passing through the detector will be far larger, tantamount to striking gold on a universal scale.
“If history is our guide, we may learn the answers to questions we don’t even know to ask right now,” says Bonnie Fleming, a physics professor at Yale and deputy research officer on neutrinos at Fermilab.
Neutrinos are tricky little things. The extremely tiny particles are among the most abundant in the universe. They don’t interact much with anything and travel close to the speed of light. In fact, 3 trillion neutrinos just flew through your body while you read the last two sentences — and that’s the big challenge for researchers.
“Maybe it makes you feel better that they only just pass through you, but if you’re actually trying to measure them, it means that you need these really intense beams and gigantic detectors to be able to have just a couple interact and measure them,” Fleming says.
Experiments already underway on neutrinos lack the sensitivity and massive scale needed when you’re essentially “looking for a needle in the haystack,” Fleming says. “To do this kind of measurement, you need all the right ingredients.”
To measure the smallest things, everything must be bigger: Scientists require more neutrinos, larger detectors, more powerful beams and a greater distance to travel, and everything needs to be deep underground to shield it from cosmic rays.
Also required: the international physics community coming together in one spot.
“Eventually you get to the scale where one organization, one science lab, one country can’t push the boundary to the next level,” says Chris Mossey, deputy director for the Long- Baseline Neutrino Facility. That’s where the scientists from more than 160 institutions come in, including Europe’s CERN, home to the Large Hadron Collider, the world’s largest and most powerful particle accelerator.
Over the next decade, they will use cutting edge, state- of- the- art technology to build the detector and create data collection systems and algorithms that capture and analyze what’s happening inside. The complicated process involves a range of tasks, including creating electronics that can function in temperatures around minus 300 degrees Fahrenheit. The reason for the “world’s largest ice box,” as Mossey puts it, is liquid argon, which requires the chilly environment.
Liquid argon, a noble gas, is what neutrinos — and antineutrinos, their counterpart, just like matter and antimatter — hit in the detector, allowing scientists to see what occurs on the rare occasion the mysterious particles interact with atoms. Differences in the numbers and properties of neutrinos vs. antineutrinos would hint at why matter dominates antimatter in our universe and show whether neutrinos played a role in its formation.
“If we don’t see a difference, there’s still a big mystery and a puzzle,” Fleming says. “If we do see something, it’s a big piece of the puzzle for why we exist.”
Before the first neutrino beam travels from Illinois to South Dakota, Lead’s decommissioned Homestake Gold Mine and some of its 370 miles of tunnels will undergo major renovations.