Case Western Reserve physicists are part of a science project with the potential to be at least as huge as this month’s Higgs boson discovery—if not even greater.
First described more than four decades ago, the Higgs boson is a subatomic particle that gives other particles mass. But that’s not enough for Case Western Reserve faculty members Tom Shutt and Dan Akerib—they want to unearth what holds all of those particles together.
The two are part of a 13-institution team that selected a South Dakota gold mine as the site for their ambitious search. Specifically, they hope to find so-called “dark matter” nearly a mile below the surface. Why so far down? To have a chance to block unwanted cosmic radiation and radioactivity.
After five years of work, the team’s search will come to a head over the coming year. Just last week, workers painstakingly lowered the world’s most sensitive dark matter detector to its new home. The Large Underground Xenon detector, called LUX for short, relies on 770 pounds of liquid xenon, which must be purified in order to reveal a chance encounter with a dark matter particle.
Chang Lee, a fifth-year graduate student who is part of the Case Western Reserve team, designed then spent the last year building the xenon purification system. The five pumps, 50 valves and two large vessels linked with high-grade stainless steel piping must remove radioactive krypton that would interfere with the detector.
The krypton, which is emitted to the atmosphere when fuel rods are reprocessed for nuclear power plants, cannot be separated chemically. Lee’s system, based on a smaller version Shutt developed years ago, will use helium gas to drag the xenon gas through a charcoal filter system to separate out the krypton.
In coming weeks, the detector will be lowered into a vat of water, which is designed to block unwanted cosmic radiation and radioactivity. Workers then will install a cooling system that, Case Western Reserve post-doctoral researcher Carmen Carmona, has spent the last year testing above ground. She’ll retest the system underground digs over the next several weeks.
Scientists believe dark matter makes up about 30 percent of the universe and provides the gravity that holds galaxies together. Evidence of the matter has been seen but the matter itself, believed by many to be weakly interactive massive particles, or WIMPS for short, has not been detected.
A discovery of WIMPs would solve an 80-year-old cosmic mystery story and provide evidence for a new state of matter that could also show up at the Large Hadron Collider in Geneva.
The Case Western Reserve team aims to begin data collection in South Dakota before year’s end.