Huge underground search for mysterious dark matter begins


              Researchers at the Sanford Underground Research Facility in Lead, S.D., discuss conditions on Dec. 8, 2019 at the underground laboratory that was once used as a gold mine. Scientists have begun a new search for mysterious dark matter in a former gold mine a mile underground. Dark matter makes up the vast majority of the mass of the universe but scientists don't know what it is.  (AP Photo/Stephen Groves)
            
              A lab worker wearing a full-body suit to avoid contaminating the dark matter detector works in the Sanford Underground Research Facility in Lead, S.D., on Dec. 8, 2019.  Scientists have begun a new search for mysterious dark matter in a former gold mine a mile underground. Dark matter makes up the vast majority of the mass of the universe but scientists don't know what it is. (AP Photo/Stephen Groves)
            
              A lab worker wearing a full-body suit to avoid contaminating the dark matter detector works in the Sanford Underground Research Facility in Lead, S.D., on Dec. 8, 2019. Scientists have begun a new search for mysterious dark matter in a former gold mine a mile underground. Dark matter makes up the vast majority of the mass of the universe but scientists don't know what it is. (AP Photo/Stephen Groves)
            
              Aaron Manalaysay, the physics coordinator of Lawrence Berkeley National Lab's experiment, explains how the underground detector will interact with dark matter in the Sanford Underground Research Facility in Lead, S.D., on Dec. 8, 2019. Scientists have begun a new search for mysterious dark matter in a former gold mine a mile underground. Dark matter makes up the vast majority of the mass of the universe but scientists don't know what it is.  (AP Photo/Stephen Groves)
            
              Aaron Manalaysay, the physics coordinator of Lawrence Berkeley National Lab's experiment, explains how the underground detector will interact with dark matter in the Sanford Underground Research Facility in Lead, S.D., on Dec. 8, 2019.  Scientists have begun a new search for mysterious dark matter in a former gold mine a mile underground. Dark matter makes up the vast majority of the mass of the universe but scientists don't know what it is. (AP Photo/Stephen Groves)
            
              This photo provided by Sanford Underground Research Facility shows members of the LZ team in the LZ water tank after the outer detector installation in Lead, S.D.  Scientists have begun a new search for mysterious dark matter in a former gold mine a mile underground. Dark matter makes up the vast majority of the mass of the universe but scientists don't know what it is.  (Matthew Kapust/Sanford Underground Research Facility via AP)
            
              This photo provided by Sanford Underground Research Facility shows the LZ Outer Detector, used to veto radioactivity that can mimic a dark matter signal in Lead, S.D. Scientists have begun a new search for mysterious dark matter in a former gold mine a mile underground. Dark matter makes up the vast majority of the mass of the universe but scientists don't know what it is. (Matthew Kapust/Sanford Underground Research Facility via AP)
            
              This photo provided by Sanford Underground Research Facility shows the LZ central detector in the clean room at Sanford Underground Research Facility after assembly, before beginning its journey underground in Lead, S.D.  Scientists have begun a new search for mysterious dark matter in a former gold mine a mile underground. Dark matter makes up the vast majority of the mass of the universe but scientists don't know what it is. (Matthew Kapust/Sanford Underground Research Facility via AP)
            
              Two researchers walk through an old mining tunnel to what is now the Sanford Underground Research Facility in Lead, S.D., on Dec. 8, 2019. The laboratory houses a dark matter detector.  Scientists have begun a new search for mysterious dark matter in a former gold mine a mile underground. Dark matter makes up the vast majority of the mass of the universe but scientists don't know what it is. (AP Photo/Stephen Groves)
Huge underground search for mysterious dark matter begins