Researchers Complete Heart of Dark Matter Detector in Lead

Aug 6, 2019

Researchers examine the xenon detector after its completion on July 26.
Credit Matt Kapust, courtesy of Sanford Underground Research Facility

Researchers at the Sanford Underground Research Facility in Lead say they’ve taken a huge step forward in the quest to confirm the existence of dark matter. Late last month, they finished assembling the key piece of the LUX-ZEPLIN experiment’s xenon detector. 

Proving the existence of dark matter requires enough precision to catch two flashes of light that would be undetectable to human eyes. Scientists believe those flashes happen if a dark matter particle collides with a xenon atom.  

The newly-completed Time Projection Chamber will hold ten tons of liquid xenon and hundreds of sensors. But to protect such sensitive equipment, scientists spent nearly a year in highly controlled conditions during assembly.

Nicolas Angelides is the on-site cleanliness monitor. He says because the detector is so sensitive to radioactivity, every single piece of material needed to be individually screened for radio-purity. And then there’s the simple issue of dust:

“Between having air that had been filtered several times and through carbon filters, and the fact that everything gets wiped several times, and layers and layers of clean-room gear that goes into this, I think we’ve created a very, like, ridiculous set of circumstances where we try to keep all dust away.”

But now that the Time Projection Chamber is complete, researchers are the closest they’ve ever been to collecting data and—they hope—confirming dark matter’s existence.

Angelides says this is a huge step, and he doesn’t expect it to be matched in the next decade at least.

“To me, the impact of standing next to something that will have a great impact, that won’t only be local but will last through generations of experiments—that to me is quite strong. And seeing the TPC is realizing that this is happening.”

Next, researchers will seal the TPC in a cryostat vessel and move it to the 4850 level of the Sanford Underground Lab to fill it with ten tons of liquid xenon.

And then…they watch and wait.