Have We Finally Detected Dark Matter?

Dark Matter

The physicists of the LUX-ZEPLIN (LZ) experiment have published the results from their dark matter detector first scientific run.

The LZ detector is the most sensitive dark matter detector in the world, and the team announced that the experiment worked as expected and published “significant results,” revealed a press release.

Although no dark matter was detected in this first round of experiments, the signs are promising for a team that intends on using the machine to unravel one of the great mysteries of the universe.

Dark matter detector team kickstarts cosmic experiments

Located underground in South Dakota, the LZ detector composed of multiple nested of liquid xenon tanks, each of 1.5 m tall & 1.5 m wide. It is located underground so there will be as little background noise as possible for experiment to detect elusive dark matter particles.

Dark matter particles are expected to fly through space and eventually bounce-off one of the xenon atoms. This will excite the free electrons into the flash that will be recorded by experiment.

The first run for LZ detector lasted 60 days b/w December 25 to May 16. However, the scientists point out that they are playing a long-awaited game.

“We’re looking for very low energy recovery by the standards of particle physics. It’s a very, very rare process, if it’s visible, Hugh Lippincott, a physicist at UC Santa Barbara and a member of the LZ team, said at a press conference yesterday, July 7. “You can shoot a dark matter particle across 10 million light-years of lead, and expect only one interaction at the end of that light-year.”

Dark matter is the mysterious, unexplained matter that makes up about 85% of the total mass of the universe. Although it has never been directly detected, we know it is there due to its gravitational effect it has on observable space objects.

One of the main candidates targeted by dark matter detection experiments, such as the DAMA/LIBRA experiment in Italy, is the WIMP, or Weakly Interacting Massive Particle. These particles have mass but barely interact with ordinary matter, which is why a super-sensitive machine is needed to detect them.

LZ detector has 1,000 days of experiments scheduled

LZ is 30 times larger and 100 times more sensitive than its predecessor, the Large Underground Xenon Experience. Although construction of the new detector began in 2018, experiments were delayed by Covid-19. Now everything seems to be going smoothly. “This collaboration worked well to calibrate and understand the detector’s response,” said Aaron Manalaysay a physicist at Berkeley Laboratory and member of the LZ team, in a Berkeley Lab press release. “It’s impressive that we turned it on a few months ago and we’ve already seen such significant results during the COVID-19 lockdown period.”

The LZ detector researchers found a total of 335 promising detections during the first 60 days of run. Nothing turned out to be WIMP, but the team was able to remove a mass-range from future experiments.

Ultimately, the team will be able to eliminate mass ranges by identifying which masses particles cannot be. This will continually narrow the parameters for future experiments, making it more likely that WIMPs will-be detected in subsequent attempts.

LZ detectors has 1000 operational days scheduled, which means about 20 times more data is collected. And each dataset is more likely than the previous dataset to finally reveal the great secrets of dark matter.