The world’s most sensitive dark matter detector has become online

Individual contributors have become less important in scientific fields as the discipline itself has matured. Some individuals still highlight their discoveries, such as Peter Higgs with the Higgs boson, who also theorized around the same time. However, the actual data that eventually awarded Dr. Higgs and François Englert the Nobel Prize was collected by the Large Hadron Collider, arguably one of the largest technical projects that took thousands of scientists decades to design, build and test.

Subatomic particles aren’t the only things that need large and complex detectors to study. With the help of an underground research facility in South Dakota, a team from Lawrence Berkeley National Laboratory has developed, deployed and tested the world’s most sensitive dark matter detection system.

The project, known as LUX-ZEPLIN, or LZ, has a history that would give any project manager nightmares. A team of 250 scientists and engineers from 35 different institutions collaborated on the project, whose primary detector was delivered to his underground home in South Dakota before the COVID pandemic forced many of those participants to stay in home institutions for the next two years.

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Video explaining the search for Dark Matter.

Despite all of LZ’s problems, in December of 2021, it was officially brought online and started collecting data. This data formed the basis of a recent research paper, proving that LZ is the most sensitive dark matter detector ever.

This does not mean that she actually saw any dark matter on her first run. Notoriously difficult to detect using any method other than gravity, dark matter remains a mystery to this day. But the scientists have refined the detection methodology that they believe will help them understand it better, and it is this technology that forms the basis of the LZ system.

Inside the main LZ detector.  It is usually filled with liquid xenon.
Inside the main LZ detector. It is usually filled with liquid xenon.
Credit – Matthew Kapust

A giant tank filled with liquid xenon comprises the bulk of the system, with an array of photomultiplier tubes (PMTs) that can detect when one of the many xenon atoms collides with a particle that can “simulate a dark matter signal.” In this case, the atom lights up, which is then detected by one of the PMTs, which can also isolate the spatial region and the direction in which the particle was traveling.

If the detector itself was above ground, many of these particles would create more noise than necessary compared to a dark matter signal. Hence, why is the detector located underground at the Sanford Underground Research Facility (SURF). SURF also hosts other sensitive experiences that take advantage of the protection provided by the Earth’s surface, so the LZ fits in perfectly with the rest.

Schematic (left) and illustrative (right) of a running LZ experiment.
Schematic (left) and illustrative (right) of a running LZ experiment.
Credit – LZ Collaboration / LZ / SLAC

So far, the LZ has only a few months of operation, but even those results intrigue the team that initially designed and built the detector. However, there is a lot of science to come, with a plan currently in place to collect 20 times more data than it has so far. Given the difficulty of detecting dark matter and the general tendency of science that more data is better, this seems like an excellent suggestion for finding dark matter if it exists. The experiment, using the Latin word for light in its name, may be the first to shed some light on the mystery of dark matter.

Learn more:
SURF – Researchers record successful start-up of the LUX-ZEPLIN dark matter detector at Sanford Underground Research Facility
LBNL – LZ Dark Matter Experiment
UT – New Dark Matter Detector Draws Void in First Test Round
UT – Searching for dark matter inside Earth

main picture:
Some of the team members responsible for the LUX-ZEPLIN trial.
Credit – Matthew Kapust