The Xenon collaboration posted a paper today on the arXiv with their latest results. No, they haven’t seen dark matter. This is a preliminary data set, and the main point of the paper is to show that the detector is working as planned, and that the background (read: anything other than dark matter) is at a remarkably low level. This bodes well for their future constraints.
The New York Times has a brief article on the results, with one of the more amusing lines I’ve seen: “…the clarity with which they saw nothing spurred hopes that such experiments are approaching the rigor and sensitivity necessary to detect the elusive gravitational glue of the cosmos.” This is perfectly accurate: they have developed a way to see nothing very, very clearly. What this means is that, if they ever actually see anything, we’ll know it’s not nothing. And this is precisely the challenge with dark matter detection. Part of the point of these latest Xenon results is that they are saying the DAMA results (which claim a detection, and which have been quite controversial) are even more likely to be nothing. In this case, clearly seeing nothing is really something.