LEAD — When scientists deploy the LUX detector in the Sanford Underground Lab the dark matter experiment will become one of the deepest in the world — immediately competing with the largest dark matter search in the world at the Large Hadron Collider in Switzerland.

The Large Hadron Collider, which, along with CERN laboratory recently enjoyed a plethora of publicity with the success of the Tom Hanks blockbuster “Angels and Demons,” houses the two largest multi-faceted particle physics experiments in the world, with searches including dark matter. Following the movie production — which scientists say contains gross inaccurate depictions of the science that occurs at CERN — scientists jumped on the film’s momentum and notoriety, using it to launch a worldwide education campaign about the experiments that occur. One of the facilities at CERN, the Large Hadron Collider, houses the two largest dark matter searches in the world — ATLAS (A Toroidal LHC ApparatuS) and the Compact Muon Solenoid (CMS). Those experiments, housed in a massive, shallow underground tube that is a 17-mile circumference ring, accelerate protons at ultra-high speeds to create dark matter particles. The experiments will search for the absence of energy after the particles collide, using that as evidence of dark matter rather than directly detecting dark matter particles.

Conversely Dr. Rick Gaitskell, one of the lead scientists for the Large Underground Xenon detector, which is slated to be set up at the 4,850-foot level of the Sanford Lab next fall, said his experiment will be positioned to directly detect the weakly interacting massive particles (WIMPS) that make up dark matter. As soon as he flips the switch on his detector, Gaitskell said, it will become the most advanced dark matter search in the world.

“We’re being fairly bold here at the Sanford Lab,” Gaitskell said. “This instrument is one that really does give us a shot to leap well beyond existing scientific dark matter experiments. It’s an entirely new regime of the very real prospect of discovery.”

Using liquid Xenon, which is transparent, and a series of ultra-sensitive photon multiplier tubes, Gaitskell will seek to detect the particles as tiny flashes of light. The depth of Gaitskell’s detector is key, as it will be far away from naturally occurring cosmic rays on the earth’s surface which interfere with the detection of dark matter particles. Even at nearly a mile beneath the earth’s surface, Gaitskell said theorists are unable to pinpoint how often dark matter particles will interact with his detector — with some of the closest estimates being from once a week to once a month.

“So we have to do our best to shield out every other possible form of radioactivity of backgrounds and cosmic rays,” Gaitskell said. “The reason we go 4,850 feet down is because as we are standing here on the surface it is a few thousand cosmic rays passing through my hand in a second. When you arrive at the 4,850 you are actually waiting about a year for a cosmic ray to go through your hand. This type of experiment cannot be done on the surface. You need a deep underground lab to do it.”

Though both methods are vastly different, Dr. Meenakshi Narain, associate physics professor at Brown University who is also involved with the CMS experiment at the Large Hadron Collider, said they will complement each other. With the Large Hadron Collider capable of creating dark matter particles, and the direct detection capabilities of the LUX, Narain said scientists will be able to combine their findings to create a more coherent understanding of the universe.

“Basically we combine the results from the direct detection experiments
like LUX with those of the LHC experiments like CMS to provide a
complete understanding of what dark matter is. If the LHC can create the
dark matter particles then we can study their quantum properties in
detail at CMS – but we will not be able to prove that they are actually
the dark matter that surrounds us. LUX can detect the dark matter
directly and make that connection – that the particles we study at CMS
are actually the same particles that make up dark matter – but LUX will
not be able to study their properties like CMS. That’s how the two
searches are complementary to each other. They go hand in hand to make
the global picture.”

Though scientists only understand what comprises about 5 percent of the universe, Dr. Greg Landsberg, physics professor at Brown University who is also working on the CMS experiment said the discovery of dark matter will increase that understanding to 25 percent — a huge advance with benefits to the scientific and general populations. Additionally, “The thing that makes the dark matter particles is that they have very long lifetimes,” Gaitskell explained. “In fact, they are stable on the lifetime of the age of the universe and as a consequence, they are still with us. They have been generated in such large numbers that they are the dominant mass of the universe. The vast majority of mass in the universe, the thing that holds it together gravitationally, is this dark matter particle. It was generated (during) the big bang.”