Dark-matter detector records three candidate events

Nature : Between 2003 and 2008 the Cryogenic Dark Matter Search (CDMS) used silicon detectors cooled to 40 mK and located deep in a mine in Minnesota to seek evidence of weakly interacting massive particles (WIMPs), one of the possible forms of dark matter. When a particle collides with the detectors, the interaction is detected as an increase in temperature. Despite the shielding provided by the mine, it is difficult to separate WIMP collisions from background events. Two previous CDMS-detected events have been shown to involve only non-WIMP particles. Now Kevin McCarthy of MIT and his colleagues, who have been analyzing the data collected by the project, have detected three collision events that may be indicative of WIMPs. The three new events occurred when the background should have produced just 0.7 such events. However, the strength of the signal was not strong enough to be considered a true discovery. The interactions, if shown to involve new particles, would give them masses of 8.6 GeV, which is much lower than expected for most theorized WIMPs. The SuperCDMS experiment and other WIMP detectors may provide the evidence necessary to confirm or refute the potential discovery.