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SURF designated as American Physical Society Historical Site | Local News

LEAD — “Ray was really a Renaissance Man. He could do anything.”

That’s how Nobel Laureate Dr. Ray Davis’ son-in-law, George Klemm described the late physicist, who did his Nobel prize winning neutrino research at the 4850-level of the former Homestake Gold Mine. On Friday, the American Physical Society officially designated the Sanford Underground Research Facility (SURF) as a Historic Site, in recognition of Davis’ historic contributions to the scientific community by his neutrino discoveries in the area now referred to as the Davis Cavern.

The event was marked with a visit from all five of Davis’ children and their spouses. The Davises, along with representatives from the American Physical Society, toured the Davis Cavern, which now houses groundbreaking experiments in dark matter and neutrinoless double beta decay.

Jonathan Bagger, CEO of the American Physical Society, and Phil Bucksbaum, president of the society, were also present to mark the occasion. Others, including Davis’ widow, Anna, watched the small underground ceremony through a live video feed on the Internet.

For all but one of the Davis children, this was their first time underground to see the site of their father’s work. In the 1960s, when Davis’ experiment was operating in what was then an active gold mine, women and children were not allowed in the mine. But Andrew Davis, the eldest son, remembers how thrilled he was to be an 18-year-old boy and able to go underground.

“We had been across the country, and he had spent the summer in California collaborating with Frederick Reines, who won the Nobel Prize for discovering the anti-neutrino,” Andrew said. “We drove across the country with a station wagon and a popup tent trailer, with five kids and two adults. We stopped here on the way back. He took me down into the mine and that was a big thrill. It was not all bright and shiny the way everything is now.”

The American Physics Society Historical Site dedication included the unveiling of a permanent plaque at the Davis Campus, which was mounted on a piece of metal taken from the large tank Davis filled with dry cleaning fluid to detect neutrinos. Curtis Jones, a technician and welder at the Sanford Lab, welded the ensemble in a seamless tribute to the Nobel laureate’s work on him.

“Today we celebrate the historic achievements realized in this facility, as well as the scientific legacy that SURF continues to advance in a wide range of science disciplines,” said SURF Communications Director Constance Walter on behalf of Executive Director Mike Headley.

In his speech, Headley mentioned one of the largest dark matter experiments in the world — the LUX-ZEPLIN, which seeks to understand the makeup of approximately 85% of the matter in the universe from its position in the Davis Cavern. He also mentioned the Long Baseline Neutrino Facility that is currently being excavated, with 800,000 tons of rock removed to make room for the Deep Underground Neutrino Experiment (DUNE). The experiment is being led by Fermilab and is in partnership with 1,400 collaborators from more than 200 different institutions in 30 countries. It is the most expensive science experiment in the US

“DUNE will push the limits of our understanding of neutrinos and the origins of the universe, and it will help us understand why we are here in a matter dominated universe,” he said.

Headley explained that Dr. Ed Kerns from Boston University nominated SURF for the historical site designation. Kerns was unable to attend, but Bagger explained that the APS has 50,000 members spread across universities, labs and industry throughout the United States. In 2005, he said the APS Committee on Historic Sites was formed to recognize places of interest and historical importance to the physics community. SURF was one of two sites out of 25 nominations to be selected for the honor, and it is one of about 50 sites that have already been chosen.

Bucksbaum was on hand to give some history about Davis’ experiment.

“This is a rightful honor for the deepest underground research laboratory in the United States,” he said. “It is the place where it was discovered that the sun shines because of nuclear fusion. This is really an inspiration to researchers around the world. In 1965 Ray, who was a chemist at Brookhaven National Lab, began building an experiment deep in the Homestake Mine with the goal of counting neutrinos from the sun to test the theory that this is how the sun generates energy. He was extremely methodical with his observations of him. He had a 100,000-gallon tank filled with dry cleaning fluid. Neutrinos from the sun, from solar fusion, turned the chlorine in that cleaner fluid into Argon atoms at the rate of a few atoms at 100,000 gallons per week. Ray spent 15 hours a day sometimes conducting underground research, and many times he didn’t even see the sun. But he was known to say he was watching the sun all the time.”

Bucksbaum explained that Davis was only able to detect one-third of the neutrinos that Dr. John Bahcall theorized existed. This was labeled as the solar neutrino problem, and many physicists were convinced that Davis’ experimental method was wrong. But Davis persevered, firm in his belief in the accuracy of his work. Many years later it would be discovered that Davis was correct, and the discrepancies actually came from the neutrinos themselves, as they changed shape and “flavor” enroute from the sun, with only one of those “flavors” interacting with the cleaning fluid to make Argon atoms.

Andrew Davis told the story about how his family never doubted their father’s methods for the experiment. “It was sort of a lonely challenge against the physics community, who were not really believers,” Andrew said. “We, of course, were all complete believers because we knew what type of guy he was. It turned out the problem was with the neutrinos and not with the model of the sun.”

On Friday, scientists who are currently working underground on various experiments, were more than happy to explain their work to the Davis children, who were delighted to see the impact of their father’s legacy.

“It’s a big thrill to see how it has really grown,” Andrew said. “His experiment on him, as big as it was with a huge tank, was really done by a couple of people. It was him and he had a technician named John Galvin. He had some engineering help from Brookhaven, but it was really a two-man experiment. Whereas if you look at the LUX experiment, there are hundreds of physicists involved with that.”

Alan Davis, one of the Nobel Laureate’s younger sons who was on his first trip underground to see the space, agreed. “This is great to see the room where it all happened and imagining it filled with water and the old tank in there. When Ray was here this was basically the only experiment going on in the middle of an active mine. To have that be able to continue after the mine shuts down and turn it into a real underground laboratory is great.”

Alan also reminisced about his father having cocktail parties at their home on Long Island, NY, where scientists gathered to “talk shop.” He also talked about spending Fridays swimming at Brookhaven National Lab.

Nancy Klum and Martha Kumler, Davis’ two daughters, said their father was known for his fun way of teaching the children when they were out. Family outings would often be marked with Davis pulling out a magnifying glass to point out interesting insects or blades of grass. Some of the family’s best memories, they said, were many years spent sailing on a boat Davis built.

The American Physics Society initially named SURF as a Historical Site in 2020. However the official dedication was delayed due to the COVID-19 pandemic.

The APS Historic Sites Initiative works to increase public awareness of noteworthy physics-related events and discoveries. Each year, APS chooses a select number of member-nominated sites to be formally recognized, using a number of criteria to select the sites, including significant contributions of the site or an individual to the advancement of physics on a national or international level.

Ray Davis passed away in 2006 at the age of 91.

On May 20, 2022 the SD Science and Technology Authority, the managing entity for the SURF, will celebrate 10 years of operations at the Davis Campus.

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