The greatest mystery in physics The hunt for dark matter remains unsuccessful for the time being
Researchers have analyzed the largest data set of a dark matter detector to date. They did not discover what they were looking for. But they did catch a glimpse of tiny particles from the interior of the sun.
08.12.2025, 23:15
SDA
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- Scientists have been searching for dark matter for decades.
- They were hoping for results from a huge data set - but were disappointed.
- Now they want to intensify the search and increase the sensitivity of the detector in the USA.
Even after analyzing a huge data set, the hunt for dark matter remains unsuccessful. In an experiment in which Swiss researchers were also involved, the strongest evidence to date of a rare process of so-called neutrinos from a fusion process in the core of the sun was measured.
This result of the Lux-Zeplin experiment was published on Monday by the research collaboration. The University of Zurich (UZH) is also part of the collaboration. The experiment is being led by the Lawrence Berkeley National Lab of the US Department of Energy.
As the researchers emphasize in the press release, the result confirms the exceptionally high sensitivity of the detector. An independent review of the results and publication in a scientific journal are still pending.
One of the greatest mysteries
Dark matter is one of the biggest unsolved questions in physics. It makes up around 85 percent of the matter in the universe and yet nobody knows what it is made of. Because dark matter does not emit, absorb or reflect light, researchers have to find other ways to make it visible.
Just two weeks ago, a Japanese researcher made headlines when he declared that he had observed signals from dark matter. "I and most of my colleagues think that this was unfortunately not the big breakthrough we all hoped for," said physicist Björn Penning from the University of Zurich (UZH), who was involved in Lux-Zeplin, to the Keystone-SDA news agency. The paper comes from a single author and is based heavily on statistical assumptions.
Detector deep underground
The Lux-Zeplin detector is an instrument that attempts to detect dark matter. More precisely, researchers use it to search for so-called "WIMP" (Weakly Interacting Massive Particles), hypothetical particles that are considered to be the most important candidates for dark matter. Lux-Zeplin is located in a former gold mine tunnel around 1.5 kilometers underground at the Sanford Underground Research Facility (Surf) in South Dakota, USA.
The detector contains ten tons of extremely pure, liquid xenon. When a particle - be it a WIMP or a neutrino - hits a xenon atom, it emits a tiny flash of light and electrons. These signals are registered by highly sensitive sensors. The detector is made of particularly low-radiation materials and shielded from interfering cosmic radiation by several layers. This is the only way to measure the extremely rare interactions at all.
Longest observation phase evaluated
In this large data set, the researchers were able to detect so-called boron-8 neutrinos, i.e. neutrinos that are produced deep inside the sun during nuclear fusion. Using the detector, they were able to observe the neutrinos via a very rare process in which a neutrino not only hits a single particle in the atomic nucleus, but also impacts the entire nucleus simultaneously. This process was only demonstrated for the first time a few years ago. This collision causes only a tiny jolt in the nucleus. This is precisely why it is extremely difficult to measure.
The research collaboration is already planning the next steps. By 2028, the detector should collect more than 1000 days of data and thus further increase its sensitivity.
