LUX exceeds sensitivity goals

Last week, the Large Underground Xenon (LUX) collaboration announced a whole new level of sensitivity for its dark matter experiment. Although no dark matter particles were found, LUX’s sensitivity far exceeded the goals for the project. The results give researchers confidence that if a particle had interacted with the detector’s xenon target, they almost certainly would have seen it. 

 “It would have been marvelous if the improved sensitivity had also delivered a clear dark matter signal. However, what we...

Fire doesn't stand a chance with Majorana suppression plan in place

The Majorana Demonstrator has an impenetrable shield made up of six layers of various materials designed to block out minute traces of radiation. Extra care needs to be taken with the last layer—12 inches of polyethylene, a combustible material that requires a defense-in-depth fire protection plan to mitigate fire hazards. 

Every prevention measure added, is a significant increase in fire protection, said Kathy Carney from Oak Ridge National Laboratory and the environmental, health and safety manager for the...

ERT stages multi-agency drill

Emergencies happen all the time—at home, at play and at work. And when they do, you need to be prepared. That’s why the Sanford Underground Research Facility and its Emergency Response Team regularly carry out evacuation drills. Last week, the team went a step farther by staging and participating in a multi-agency emergency drill. 

“You train to be prepared for any emergency and we’re prepared because we train,” said John Emick, ERT lead. 

The team started with a table top exercise, with all agencies...

Preserving a piece of history

For just over 125 years, Homestake Mine operated the deepest, richest gold mine in North America. From 1876 to 2001, more than 40 million ounces of gold and 9 million ounces of silver were removed from a vast expanse of underground tunnels that stretched from the surface to the 8,000-foot level. As operations expanded and the company introduced new technologies, it built new buildings, removed old buildings and retired outdated equipment.

Homestake was selected as the site for a deep underground research...

TDM: Ensuring safe access for science

Every day, crews of infrastructure technicians convey people and equipment up and down the Yates Shaft. And it is mostly in this context that scientists, lab personnel and visitors see them. What we don’t see is the work the crews do to ensure every person—and everything—gets where they need to be, safely. 

“During the day, we mostly cater to science,” said Pat Urbaniak, team lead. “The night shift is where we do most of the challenging work.” That challenging work includes top-down maintenance (TDM), which...

It’s a star stuffed Neutrino Day

July 4, 2016
David Vardiman, geotechnical project engineer at Sanford Lab, engages with Neutrino Day visitors about the geology of the northern Black Hills and the transition from mining to excavating rock for large science experiments.

Sanford Lab’s Neutrino Day 2016 celebrated the star stuff in all of us through activities, presentations, an art competition and displays. Presentations and videoconferences ranged from the NASA 2030 Mars Experience, to dark matter, to neutrinos, to the composition of the universe. 

Manuel Brother’s Park was filled with children doing hands-on science activities. Esther Mandy, a 7-year-old visiting Neutrino Day for the first time, said her favorite part of the day was: “how people study artifacts.” Although Esther said her favorite thing about science is stars, she loves all “sciency-stuff.” 

At the Sanford Lab Homestake Visitor Center, David Vardiman, geotechnical project engineer at Sanford Lab, gave a geology demonstration that drew children and adults alike. Vardiman focused on the differences between mining for gold and building large caverns for big science experiments. “The response from children was amazing,” he said. “They loved seeing the fossils, gold samples and geotechnical cores. That was really the highlight of the demonstration.” 

Steve Rokusek has been a staple of Neutrino Day for several years and is one of the biggest draws, introducing children to advanced science in a way that inspires and excites. His “wild science” demonstrations included making clouds out of nitrogen and bubbles, which helps kids learn about the otherwise complicated physics of natural phenomenon.  

Jason Crusan of NASA, who gave the keynote talk Friday night and was the featured guest for South Dakota Public Broadcasting’s Science Café at the Lotus Up Café, discussed the 2030 Mission to Mars and the nitty-gritty details about NASA’s efforts to build habitats for living in space. —Continued on page 2

—From page 1

Brynn Scogan, from Sioux Falls S.D., said, “I was really excited to meet him, and learn about what he’s doing to get people into space.” Crusan answered questions from the audience that focused on everything from water in space to living on the International Space Station to discovering life on Mars. 

More than 1,100 people attended Neutrino Day events, which included videoconferences from the underground with the Emergency Response Team and the CASPAR experiment (Compact Accelerator System for Performing Astrophyical Research), which is studying nuclear fusion in stars. 

At the Opera House, Elizabeth Worcester, member of the Deep Underground Neutrino Experiment, or DUNE, focused her presentation on neutrinos and how DUNE and the Long-Baseline Neutrino Facility (LBNF) will search for these ghost-like particle. Dan McKinsey, co-spokesperson for the Large Underground Xenon (LUX) experiment discussed dark matter and the next generation detector, LUX-ZEPLIN, which will replace LUX at Sanford Lab. 

 

LUX, now with more sensitivity

December 1, 2015
Photomultiplier tubes can pick up the tiniest bursts of lights when a particle interacts with xenon atoms.

The Large Underground Xenon (LUX) dark matter experiment, located on Sanford Lab’s 4850 Level is already the most sensitive dark matter detector in the world. Now, researchers have improved the detector’s sensitivity level, dramatically increasing its ability to find WIMPs (weakly interacting massive particles). 

Using a new set of calibration techniques, the research re-examines data collected during LUX’s first three-month run in 2013, and helps rule out the possibility of dark matter detections at low-mass ranges where other experiments had previously reported potential detections. 

“It is vital that we continue to push the capabilities of our detector in the search for elusive dark matter particles,” said Rick Gaitskell, Professor of Physics at Brown University and co-spokesperson for the LUX experiment.

Dark matter is thought to be the dominant form of matter in the universe and WIMPs are among the leading candidates. However, they interact with other matter on very rare occasions and they have yet to be detected directly.

LUX consists of one third of a ton of liquid xenon surrounded with sensitive light detectors inside a titanium vessel. On the very rare occasions when a dark matter particle collides with a xenon atom inside the detector, the xenon atom will recoil and emit a tiny flash of light, which will be detected by light sensors. So far, LUX hasn’t detected a dark matter signal, but its exquisite sensitivity has allowed scientists to all but rule out vast mass ranges where dark matter particles might exist. 

The new calibration techniques include injecting neutrons, which act as stand-ins for dark matter particles, into the detector, then track them to learn details about the recoil. The nature of the interaction between neutrons and xenon atoms is thought to be very similar to the interaction between dark matter and xenon. “It’s just that dark matter particles interact very much more weakly—about a million-million-million-million times more weakly,” Gaitskell said. He describes it as a “giant game of pool with a neutron as the cue ball and the xenon atoms as the stripes and solids.” 

Additionally, LUX scientists injected radioactive gases into the detector to better understand its response to the deposition of small amounts of energy by struck atomic electrons. The LUX improvements allowed scientists to test additional particle models of dark matter that now can be excluded.

“And so the search continues,” said Dan McKinsey, a University of California Berkeley Physics Professor and co-spokesperson for LUX and an affiliate with Lawrence Berkeley National Laboratory. “The latest run began in late 2014 and is expected to continue until June 2016. We will be very excited to see if any dark matter particles have shown themselves in the new data.”

Planning for the next-generation dark matter experiment at Sanford Lab is already underway. In late 2016, LUX will be decommissioned to make way for the much larger xenon detector of the LUX-ZEPLIN (LZ) experiment, which will be filled with 10 tons of liquid xenon—three times the volume used for LUX.

“The global search for dark matter aims to answer one of the biggest questions about the makeup of our universe. We’re proud to support the LUX collaboration and congratulate them on achieving an even greater level of sensitivity,” said Mike Headley, Executive Director of the SDSTA.

The LUX collaboration is supported by the DOE and National Science Foundation (NSF). It includes 19 research universities and national laboratories in the United States, the United Kingdom and Portugal.

 
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