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· collected 2026-08-25 · by TOI World Desk
In 2007, a gold mine in Lead, South Dakota, became the Sanford Underground Research Facility (SURF), the deepest underground laboratory in the US. The facility reaches 4,850 feet below the surface and is used by scientists from dozens of countries to study the universe and Earth. A key experiment conducted there was the Large Underground Xenon (LUX) experiment, which searched for dark matter and was found to be the most sensitive dark matter detector in the world in 2013. The facility has a total budget of $70 million, donated by T Denny Sanford, and an additional $40 million from South Dakota.
Written by the local model on 2026-08-25,
using this article's own text rather than the other coverage of the
same event (that is the story summary below).
A gold mine in South Dakota once produced millions of ounces of precious metal.
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mine → produce → metal
Today, the same site is being used to study some of the biggest mysteries in the universe.
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site → use → universe
The Homestake Gold Mine in Lead, South Dakota, operated for 125 years before it closed in 2001.
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it → operate → 2001
According to Sanford lab, during its lifetime, the mine produced about 41 million ounces of gold and 9 million ounces of silver, making it the largest and deepest gold mine in North America at the time.
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it → accord → time
The mine later took on a completely different when in 2006, businessman T Denny Sanford pledged $70 million to help revive plans for an underground research laboratory.
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Sanford → take → laboratory
Barrick Gold Corporation, which owned the Homestake property, donated land, while South Dakota committed more than $40 million to the project.
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Dakota → own → project
The efforts led to the creation of the Deep Underground Science and Engineering Laboratory, now known as the Sanford Underground Research Facility (SURF), in 2007.
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efforts → lead → 2007
Today, SURF is the deepest underground laboratory in the United States, reaching 4,850 feet below the surface.
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SURF → reach → surface
Scientists from dozens of countries work there to study questions about the universe and Earth.
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Scientists → work → universe
How mine became lab
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mine → become → ?
The idea of using the mine for science was not new at that time.
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idea → use → time
Research had already begun there decades before mining even ended.
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mining → begin → ?
In the mid-1960s, physicist Raymond Davis Jr built the Brookhaven Solar Neutrino Experiment deep inside the Homestake Mine.
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Jr → build → Mine
His experiment used a 100,000-gallon tank filled with perchloroethylene, a chlorine-containing dry-cleaning fluid, to detect neutrinos coming from the Sun.
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experiment → use → Sun
He later recieved the Nobel Prize in Physics in 2022 for detecting cosmic neutrinos.
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He → recieve → neutrinos
Neutrinos are extremely difficult to detect because they interact very weakly with matter.
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they → detect → matter
The experiment therefore needed protection from unwanted signals that could interfere with the measurements.
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that → need → measurements
The mine's great depth provided an environment suited to this type of research.
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depth → provide → research
Davis continued his work for nearly three decades in an underground area that later became known as the Davis Cavern.
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that → continue → Cavern
Scientists then began pushing for the site to be converted into a permanent underground research laboratory.
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site → begin → laboratory
Search for dark matter
Once the site was developed as a modern research facility, scientists began installing major physics experiments deep underground.
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scientists → search → experiments
It was installed on the 4,850-foot level and was designed to search for dark matter.
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It → instal → matter
Dark matter is a mysterious form of matter that scientists believe exists, but it has not been directly detected.
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it → believe → matter
It does not interact with light in the way ordinary matter does, making it difficult to study.
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it → interact → way
In October 2013, after an initial 80-day run, LUX was found to be the most sensitive dark matter detector in the world.
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LUX → find → world
Further analysis confirmed its sensitivity in 2016, the same year the experiment was decommissioned.
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experiment → confirm → 2016
LUX was later followed by a second-generation experiment, LUX-ZEPLIN, or LZ.
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LUX → follow → experiment
It began operating in 2021 and was announced as the world's most sensitive dark matter detector when its first results were released on July 7, 2022.
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results → begin → July
The underground setting remains central to these experiments.
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setting → remain → experiments
SURF's deep location allows scientists to conduct highly sensitive searches in an environment protected by thousands of feet of rock.
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scientists → allow → rock
Looking for rare radioactive decay
Another major experiment at SURF has been searching for something even more elusive.
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experiment → look → something
The Majorana Demonstrator operating from 2015 to 2021, was used to search for neutrinoless double-beta decay, a rare type of radioactive decay that has never been observed.
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that → operate → decay
Finding this decay could help explain why matter exists in our Universe.
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matter → find → Universe
The experiment's final results, published in early 2023, showed that the techniques used by the collaboration could be applied to a much larger experiment.
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techniques → publish → experiment
The collaboration is now working with another germanium experiment to develop the Large Enriched Ge Experiment for Neutrinoless ββ Decay, or LEGEND.
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collaboration → work → Decay
The same year Davis received the Nobel Prize, the Homestake Mine closed.
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Mine → receive → Prize
Research beyond physics
The extreme conditions underground have also opened the door to research outside particle physics.
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conditions → open → physics
Scientists have studied microbial lifeforms living in the underground environment.
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Scientists → study → environment
Some of this research has been linked to questions about medicines, biofuels and carbon sequestration.
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Some → link → medicines
SURF says research carried out there has also helped inform the search for life on Mars.
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research → say → Mars
…and 5 more, not listed.
