Detecting the presence of dark matter in space is rather easy, but that doesn't tell us what dark matter actually is. Scientists may have had better luck in a Minnesota mine: projects occupying the mine are using ultracold pucks of material to detect dark matter interactions, and may be seeing the first signs of success. The researchers behind the Coherent Germanium Neutrino Technology (CoGeNT) recently submitted a paper on signals detected with their germanium puck. The results are similar to those obtained with CDMSII, and might indicate the presence of weakly interacting massive particles, or WIMPs.

The pucks used in the experiments are lowered to temperatures of a few dozen millikelvins and kept in wait to be struck by errant dark matter particles. The interactions the pucks have been detecting have energies of a few thousand electron volts, most of which would be classified as a lighter-mass variety of WIMPs, although they could be another variety of particle entirely.

The CDMSII has been able to detect a significant count of particles in the 8-10 keV range, though the lower limit of its detection is 2.7 keV. The CoGeNT puck detected a different peak, around 1.29 keV. The different energies may suggest that there's a small collection of dark matter particles out there.

In the paper, which has yet to undergo peer review, the authors are cautious about calling the signals a triumph. They note that the interactions could be produced by "muon-induced neutrons" or just noise. However, the pucks are shielded against such particles, and researchers point out such spikes in noise would be uncharacteristic of the detectors. The authors state they will continue to refine their data to "exhaust less exotic possibilities."