From Sanford Underground Research Facility-SURF: “Teams rigorously inspect facility levels”

SURF-Sanford Underground Research Facility, Lead, South Dakota, USA.

From Sanford Underground Research Facility-SURF

Homestake Mining, Lead, South Dakota, USA.

Homestake Mining Company

March 29, 2021
Erin Lorraine Broberg

The view down a drift on the 5000 Level of Sanford Underground Research Facility. Credit: Matthew Kapust.

The Sanford Underground Research Facility (SURF) (US) is a matrix of interconnected shafts, drifts and ramps. With hundreds of miles of underground space, SURF maintains over 12 miles for science activities. Some of these areas boast concrete flooring, flush toilets, WIFI and even an espresso machine. Other spaces, however, are less maintained. While they are not used for science, adverse conditions in these areas could affect science and operations efforts elsewhere in the facility.

To ensure safe conditions the Underground Operations Department inspects every level of the facility from bottom to the top. These Annual Level Inspections assess each level’s ground support conditions, structural integrity, water inflow, ventilation and other environmental issues. Inspections are done more frequently for escapeways and essential ventilation and water inflow controls.

“We have predefined points identified for each level, including legacy shafts, timber lines and any other structures that could fail at some point,” said Jason Connot, underground operations engineer at SURF. “At each point, we evaluate conditions and document changes, making sure conditions are consistent from year to year.”

Ventilation tags mark locations where crews take air flow measurements. Credit: Adam Gomez.

Level inspections ensure the infrastructure of the underground doesn’t adversely affect SURF’s mission or the experiments hosted underground. The inspections also fulfill requirements outlined in the property donation agreement formed when Barrick Gold Corporation donated the facility to the South Dakota Science and Technology Authority.

For 120 years the Homestake Mining Company excavated more than 370 miles of shafts; drifts; and ramps. The facility’s oldest, shallowest levels were created in the late 1800s. When the facility reopened for science, Tom Regan was among the first to begin inspecting levels for safety.

At defined points of interest, crews use spray paint to mark the date and the initials of those conducting the inspection. Credit: Matthew Kapust.

“In 2008, we reentered the underground, going top-down, level by level,” said Regan, a former employee of Homestake and SURF, now a safety consultant for SURF. “We created a checklist of items to inspect, to see what condition the facility was in. Those inspections created a baseline library for annual level inspections.”

As Regan’s crews gained more access to the underground, they installed ground support where needed and eliminated hazards throughout the facility. Crews also installed more than 50 timber water walls, supported by steel posts and angles, to prevent water inflow from accessing the Yates or Ross Shafts.

Today, the department focuses on maintaining level conditions and cataloging information. George Vandine, underground infrastructure coordinator at SURF, manages the current dataset, which captures three years of detailed information on every level of the facility.

“Saying that a legacy pipe fell down on the 4550 Level doesn’t give us enough information to repair the area,” Vandine said. “Our management system includes detailed maps, notes and photos to help teams pinpoint any issue, anywhere underground.”

Crews inspect level conditions on an Annual Level Inspection of the 1100 Level. Credit: Matthew Kapust.

After a level inspection, Vandine inputs information into the management system. From there, the Underground Operations Department prioritizes and executes repairs and mitigation projects as needed.

“When doing these annual level inspections, the key to success is really knowing the levels—understanding how levels interact with other levels, understanding airflow and water flow between levels,” Connot said, noting that he has gained valuable knowledge by working with Regan, Vandine and others. “I try to soak in that knowledge from these experienced guys so we can continue to build on their expertise.”

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About us: The Sanford Underground Research Facility-SURF in Lead, South Dakota, advances our understanding of the universe by providing laboratory space deep underground, where sensitive physics experiments can be shielded from cosmic radiation. Researchers at the Sanford Lab explore some of the most challenging questions facing 21st century physics, such as the origin of matter, the nature of dark matter and the properties of neutrinos. The facility also hosts experiments in other disciplines—including geology, biology and engineering.

The Sanford Lab is located at the former Homestake gold mine, which was a physics landmark long before being converted into a dedicated science facility. Nuclear chemist Ray Davis earned a share of the Nobel Prize for Physics in 2002 for a solar neutrino experiment he installed 4,850 feet underground in the mine.

Homestake closed in 2003, but the company donated the property to South Dakota in 2006 for use as an underground laboratory. That same year, philanthropist T. Denny Sanford donated $70 million to the project. The South Dakota Legislature also created the South Dakota Science and Technology Authority to operate the lab. The state Legislature has committed more than $40 million in state funds to the project, and South Dakota also obtained a $10 million Community Development Block Grant to help rehabilitate the facility.

In 2007, after the National Science Foundation named Homestake as the preferred site for a proposed national Deep Underground Science and Engineering Laboratory (DUSEL), the South Dakota Science and Technology Authority (SDSTA) began reopening the former gold mine.

In December 2010, the National Science Board decided not to fund further design of DUSEL. However, in 2011 the Department of Energy, through the Lawrence Berkeley National Laboratory, agreed to support ongoing science operations at Sanford Lab, while investigating how to use the underground research facility for other longer-term experiments. The SDSTA, which owns Sanford Lab, continues to operate the facility under that agreement with Berkeley Lab.

The first two major physics experiments at the Sanford Lab are 4,850 feet underground in an area called the Davis Campus, named for the late Ray Davis. The Large Underground Xenon (LUX) experiment is housed in the same cavern excavated for Ray Davis’s experiment in the 1960s.

The LBNL LZ Dark Matter Experiment (US) project at SURF, Lead, SD, USA, will replace LUX at SURF

In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The U Washington MAJORANA Neutrinoless Double-beta Decay Experiment Demonstrator experiment (US) , also on the 4850 Level, is searching for a rare phenomenon called “neutrinoless double-beta decay” that could reveal whether subatomic particles called neutrinos can be their own antiparticle. Detection of neutrinoless double-beta decay could help determine why matter prevailed over antimatter. The Majorana Demonstrator experiment is adjacent to the original Davis cavern.

The LUX Xenon dark matter detector | Sanford Underground Research Facility mission was to scour the universe for WIMPs, vetoing all other signatures. It would continue to do just that for another three years before it was decommissioned in 2016.

In the midst of the excitement over first results, the LUX collaboration was already casting its gaze forward. Planning for a next-generation dark matter experiment at Sanford Lab was already under way. Named LUX-ZEPLIN (LZ), the next-generation experiment would increase the sensitivity of LUX 100 times.

SLAC National Accelerator Laboratory(US) physicist Tom Shutt, a previous co-spokesperson for LUX, said one goal of the experiment was to figure out how to build an even larger detector.

“LZ will be a thousand times more sensitive than the LUX detector,” Shutt said. “It will just begin to see an irreducible background of neutrinos that may ultimately set the limit to our ability to measure dark matter.”

We celebrate five years of LUX, and look into the steps being taken toward the much larger and far more sensitive experiment.

Another major experiment, the Long Baseline Neutrino Experiment (LBNE)—a collaboration with Fermi National Accelerator Laboratory (Fermilab) and Sanford Lab, is in the preliminary design stages. The project got a major boost last year when Congress approved and the president signed an Omnibus Appropriations bill that will fund LBNE operations through FY 2014. Called the “next frontier of particle physics,” LBNE will follow neutrinos as they travel 800 miles through the earth, from FermiLab in Batavia, Ill., to Sanford Lab.

FNAL DUNE LBNF (US) from FNAL to SURF, Lead, South Dakota, USA

FNAL DUNE LBNF (US) Caverns at Sanford Lab.

The U Washington MAJORANA Neutrinoless Double-beta Decay Experiment (US) will contain 40 kg of germanium; up to 30 kg will be enriched to 86% in 76Ge. The DEMONSTRATOR will be deployed deep underground in an ultra-low-background shielded environment in the Sanford Underground Research Facility (SURF) in Lead, SD. The goal of the DEMONSTRATOR is to determine whether a future 1-tonne experiment can achieve a background goal of one count per tonne-year in a 4-keV region of interest around the 76Ge 0νββ Q-value at 2039 keV. MAJORANA plans to collaborate with Germanium Detector Array (or GERDA) experiment searching for neutrinoless double beta decay (0νββ) in Ge-76 at the underground Laboratori Nazionali del Gran Sasso National Laboratory (IT)(LNGS) for a future tonne-scale 76Ge 0νββ search.

CASPAR | Sanford Underground Research Facility is a low-energy particle accelerator that allows researchers to study processes that take place inside collapsing stars.

The scientists are using space in the Sanford Underground Research Facility (SURF) in Lead, South Dakota, to work on a project called the Compact Accelerator System for Performing Astrophysical Research (CASPAR). CASPAR uses a low-energy particle accelerator that will allow researchers to mimic nuclear fusion reactions in stars. If successful, their findings could help complete our picture of how the elements in our universe are built. “Nuclear astrophysics is about what goes on inside the star, not outside of it,” said Dan Robertson, a Notre Dame assistant research professor of astrophysics working on CASPAR. “It is not observational, but experimental. The idea is to reproduce the stellar environment, to reproduce the reactions within a star.”