There’s a new world record in the search for dark matter, and University of Sheffield researchers had a key part to play in achieving it.
One of the key mysteries of physics is related to working out the nature of dark matter: a hypothetical substance that is believed to make up around 85% of the universe’s total matter.
It’s difficult to detect in laboratories, with many believing it is a currently undiscovered subatomic particle – while a minority of scientists believe it doesn’t exist at all.
The LUX-ZEPLIN (LZ) experiment, led by Berkeley Lab in the USA, is hunting for dark matter in South Dakota, and this includes scientists from the University of Sheffield’s Department of Physics and Astronomy, focused on searching for weakly interacting massive particles (WIMPs) – which is one of the leading candidates that scientists believe could be the nature of dark matter.
Over 280 days of data collection, LZ has explored areas of dark matter interactions that no other experiment has reached. By not finding WIMPs at these energies, the results place further limits on what mass they could have. The experiment’s sensitivity to faint interactions helps researchers reject potential WIMP dark matter models that don’t fit the data, leaving significantly fewer places for WIMPs to hide.
Professor Vitaly Kudryavtsev, the Head of the LZ group at the University of Sheffield, said: “Understanding and tackling background events in the detector is key to the success of the experiment.
“Many groups contributed to this task, and we are happy with the significant reduction of the rate of spurious events that we are dealing with at the late stages of data analysis”.
Chamkaur Ghag, spokesperson for LZ and a professor at University College London (UCL), said: “These are new world-leading constraints by a sizeable margin on dark matter and WIMPs.
“If WIMPs had been within the region we searched, we’d have been able to robustly say something about them. We know we have the sensitivity and tools to see whether they’re there as we search lower energies and accrue the bulk of this experiment’s lifetime.”
Professor Dan Tovey, from the University of Sheffield’s School of Mathematical and Physical Sciences and member of the LZ group, said: “Starting with an observed rate of a few events per second we managed to reduce it to just a handful of them during the whole period of operation so far and these remaining events still do not match the pattern expected from WIMPs, as our extensive calibration campaigns show.”
The LZ group will continue work until at least 2028, and plans on making further breakthroughs in determining and detecting dark matter, which could help with understanding one of the key components of our universe.
