The Sun travels through space at 264 kilometers per second. It cuts through an invisible cloud that physicists call dark matter. This cloud consists of particles that barely interact with ordinary matter. But occasionally one strikes an atomic nucleus — and if we detect that impact, we can figure out where the particle came from.
The trouble is that similar impacts are caused by neutrinos (light particles that barely interact with matter). They confuse the signal like background noise. The MIMAC detector is designed like a compass for this wind. It not only registers the impact but also reconstructs its direction — like a weather vane turning into the flow.
Inside the chamber, gas is at low pressure. When a nucleus receives an impact, it leaves a track several millimeters long. Special electronics read the track shape and determine where the impact came from. A trained on examples algorithm filters out extraneous signals — by a factor of 100,000. A year and a half of observations toward the constellation Cygnus showed no signal excess, allowing the establishment of the strictest limit for such a method. The experiment proved that even a small detector with a 'compass' can compete with huge installations. In the future, this method will break through the neutrino noise and may for the first time point to the direction of a true wind of dark matter.
The MIMAC detector can determine the direction of an incoming particle with 15° precision, as if sensing which way the “wind” of invisible particles blows. And the fluorine in its gas mixture makes it sensitive to spin-dependent interactions, a kind of “sniffer” for WIMPs.