TESSERACT experiment opens new frontier in dark matter detection

A novel dark matter detector explores previously untested mass ranges, offering new opportunities for understanding fundamental particle physics.

• TESSERACT searches for low-mass dark matter particles previously inaccessible to other detectors.
• Initial tests found no dark matter signals but established unprecedented sensitivity.
• Future experiments will be conducted underground to further improve detection capabilities.

Scientists have unveiled initial results from the TESSERACT experiment, a highly sensitive detector aimed at exploring an elusive category of dark matter previously inaccessible to other experiments. The research, detailed in a paper posted to the preprint server arXiv, demonstrates that TESSERACT is already capable of probing dark matter masses significantly lighter than traditional targets, marking a crucial step forward in experimental particle physics.

A new mass regime for dark matter

Traditional dark matter searches have predominantly targeted either ultra-light axions or heavier weakly interacting massive particles (WIMPs). However, TESSERACT aims specifically at the intermediate “Goldilocks” mass range—particles about a hundred to a thousand times lighter than WIMPs, an area that has remained largely unexplored due to technical constraints.

Dan McKinsey, TESSERACT’s project director at Lawrence Berkeley National Laboratory, explained the significance: “There’s this untested window that gives us an opportunity for discovery. Our detector has the sensitivity, even at this early stage, that allows us to look for dark matter candidates no one has been able to look for before.”

Initial experiments, using silicon chips of just one square centimetre in size, already demonstrate an exceptional sensitivity. The detectors operate at temperatures close to absolute zero (approximately 8 millikelvin), using transition-edge sensors capable of detecting minuscule amounts of heat deposited by potential dark matter interactions.

Despite finding no dark matter between masses of 44 MeV/c² and 87 MeV/c², TESSERACT’s results are groundbreaking in their precision. For context, current leading WIMP experiments typically explore masses above 9,000 MeV/c², while TESSERACT probes significantly lighter particles, opening possibilities for identifying entirely new fundamental interactions.

Advancements in detection technology

A significant strength of TESSERACT lies not in its size but in its unparalleled sensitivity. The detector uses specially engineered transition-edge sensors fabricated at Texas A&M University and designed by researchers at UC Berkeley. This approach has enabled the reduction of background noise by up to 30 times compared to previous sensors, crucially enhancing sensitivity.

“The devices that we are running are so quiet compared to pretty much any other device that’s ever been run,” explained Michael Williams, co-lead of the analysis at Berkeley Lab. “There’s a really large overlap between the work we’re doing on these devices and other quantum material science. As we improve these transition-edge sensors for ourselves, we can use the same engineering to make better qubits and quantum computers.”

Looking ahead, researchers plan to dramatically enhance the experiment’s capabilities by relocating TESSERACT underground to the Modane Underground Laboratory in France. Situated 1,700 metres beneath the surface, this location will significantly reduce cosmic interference, crucial for detecting rare interactions between dark matter and regular matter. The new laboratory, expected to be operational by 2029, will enable scientists to search for even lighter dark matter particles, potentially as low as 10 MeV/c².

Complementing the main TESSERACT silicon sensors, researchers are developing additional detector modules such as HeRALD, which uses superfluid helium, and SPICE, employing crystals of sapphire and gallium arsenide. These modules will diversify detection methods and cross-validate potential dark matter signals.

“This result is the first indication that we can open up this new regime of low-mass dark matter to experimental testing,” McKinsey concluded. “This is really just the opening salvo for TESSERACT. We expect to have many more results over the next decade.”