A high-profile claim to have seen a potential signal of dark matter passing through the Earth is encountering some skepticism as independent scientists get to grips with the published data.
On 3 June, Juan Collar of the University of Chicago, and his colleagues on the CoGeNT experiment in the Soudan mine in Minnesota published data that they claimed was consistent with the signature of dark matter particles passing through their germanium detectors.
Although the group stopped short of claiming the detection of dark matter, its statement that its results were consistent with that interpretation drew intense media attention, beginning in May when Collar reported the findings at the American Physical Society meeting in Anaheim, California. This was primarily because of a tantalizing modulation – a seasonal rise and fall – in the frequency of their candidate detections, that seemed consistent with a previously unreproduced claim to have detected dark matter by the DAMA experiment at Gran Sasso in Italy.
Now, in a paper submitted to the arXiv preprint server, Thomas Schwetz-Mangold of the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, and Jure Zupan of the University of Cincinnati in Ohio, agree that there is a statistically significant modulation in the CoGeNT data, but question whether it is consistent with the dark matter explanation. “I’m not convinced it’s coming from dark matter,” says Schwetz-Mangold, “there is some tension with that explanation.”