Physicists at the Max Planck Institute have developed a novel detector using ordinary table sugar to search for lightweight dark matter particles known as WIMPs. The experiment cooled sucrose crystals to near absolute zero but detected no signs of the elusive particles after 19 hours. This approach targets interactions with hydrogen atoms in sugar, offering a new angle in the long quest to uncover dark matter.
Dark matter's existence is inferred from its gravitational effects on galaxies, yet decades of searches for weakly interacting massive particles (WIMPs)—long considered prime candidates—have yielded nothing. Traditional detectors seek flashes of light from WIMP interactions with regular matter, assuming particles roughly 2 to 10,000 times the mass of a proton. However, lighter WIMPs, which fit less neatly with galactic observations, might interact more noticeably with light atoms like hydrogen.
To probe these lighter possibilities, Federica Petricca and her team at the Max Planck Institute for Physics in Munich, Germany, created a detector from sucrose crystals. Each sucrose molecule contains 22 hydrogen atoms, providing a denser target than pure hydrogen, which is hard to use due to its low density. The researchers grew the crystals from a concentrated sugar solution over a week, then cooled them to seven thousandths of a degree above absolute zero—about 0.007 Kelvin.
They monitored for dark matter signals using an ultrasensitive thermometer to detect tiny heat increases and a photon sensor for light flashes. The setup ran for 19 hours, registering light emissions consistent with larger particles but no weaker signals that could indicate light WIMPs.
"The sugar crystals have been set up to look for possible dark matter interactions with remarkable sensitivity," says Carlos Blanco at Pennsylvania State University. He notes they could reveal extremely small recoils from light WIMPs, though it's unclear if the experiment fully excludes background sources, such as radioactive carbon-14 common in sugars.
This bittersweet result highlights ongoing innovation in dark matter hunts, detailed in a preprint on arXiv (DOI: 10.48550/arXiv.2510.00068). While no detection occurred, the method expands the toolkit for future searches.