Seven years of science in the Davis Campus

In the last seven years, a laboratory nearly a mile below the unassuming city of Lead, S.D. has been making international headlines in the global particle physics community:

"World's Most Sensitive Dark Matter Detector Completes Search"

"Majorana publishes results in 'Physical Review Letters'"

"LZ assembly begins — piecing together a 10-ton detector"

For those who were present for the official dedication of the Davis Campus on May 30, 2012, such headlines may have seemed too ambitious—if not altogether out-of-reach.

Yet, since 2012, these headlines have bled into print, proving that the 30,000 sq. ft. facility on the 4850 Level of Sanford Underground Research Facility (Sanford Lab) is capable of housing incredibly-sensitive particle physics experiments.

The first two rare-event searches to move into the Davis Campus were the MAJORANA DEMONSTRATOR (MAJORANA) and the Large Underground Xenon Experiment (LUX). 

Bill Harlan, the communications director for Sanford Lab in 2012, described the goals each experiment had at the time of the Davis Campus dedication: “MAJORANA’s goal is to prove that background noise at the Davis Campus is indeed ‘quiet’ enough to be worth the expense of searching here for neutrinoless double-beta decay, a process with an estimated half-life longer than a trillion times the age of the universe (if it happens at all). LUX too, a search for weakly interacting massive particles (WIMPs), is not only the most sensitive search yet, it’s a precursor to a bigger detector to be placed in the same spot, if it’s quiet enough.”

LUX was quiet. In 2013, after a three-month run, the detector was declared the world’s most sensitive dark matter detector. 

In 2016, when LUX completed its search, professor of physics at Brown University and co-spokesperson for the LUX experiment Rick Gaiskell announced, "With this final result from the 2014-2016 search, the scientists of the LUX Collaboration have pushed the sensitivity of the instrument to a final performance level that is 4 times better than the original project goals.” 

Meanwhile, MAJORANA was attempting a different search in laboratory just down the corridor. The goal of MAJORANA is to “demonstrate” that the collaboration’s technology—using ultra-pure crystals of a germanium isotope in a detector deep underground—could achieve background radiation levels low enough to justify building a larger detector. In 2018, the collaboration published a study in Physical Review Letters proving exactly that. 

In the Davis Campus, both LUX and MAJORANA collaborations proved their ability to achieve backgrounds low-enough to observe incredibly rare events. These findings paved the way for next-generation experiments.

The Davis Campus will be home to one of those forward-reaching experiments, the LUX-ZEPLIN (LZ) dark matter detector. LZ is currently being assembled in the same water tank that once housed its predecessor LUX. Peering down into the LZ water tank from the work deck above, researchers and engineers can see the assembly process for the 10-ton experiment underway. The Science and Technology Facilities Council's Pawel Majewski recently returned to Sanford Lab after nearly half a year away, and was thrilled with what he saw.

“I’m very excited. Activities are happening at full steam, which is great!” said Pawel, whose focus is LZ cryostat installation. “The underground area looks ready to welcome an experiment.”

MAJORANA will take an active role in preparation for the next-generation search for neutrinoless double-beta decay: LEGEND-200 (Large Enriched Germanium Experiment for Neutrinoless ββ Decay). Although LEGEND-200 will be housed in Italy at Gran Sasso National Laboratory, ultra-pure copper electroformed by the MAJORANA collaboration will be used for the experiment. 

MAJORANA will also be used to validate the detectors created for LEGEND-200. “MAJORANA has proven itself fantastic for characterizing detectors,” said Christofferson. “When detectors are created for LEGEND-200, they will be placed in the MAJORANA experiment to be validated. This helps us figure out how they respond while next-generation experiment is still being built, which is time well-spent before they go into the final experiment.”

With LZ anticipating data collection in 2020 and LEGEND-200 expecting first measurements in 2021, the physics community can soon expect more headlines rising from the underground Davis Campus at Sanford Lab.

“The Davis Campus has become exactly what we hoped for—a lab where great science is happening every day a mile underground,” said Mike Headley, the executive director of Sanford Lab. “The science results from the Davis Campus experiments have been world-leading, and we look forward to even more progress into the future.”

Read more about the Davis Campus history, renovation and dedication.

Davis Cavern Outfitting Timelapse from Sanford Lab on Vimeo.