Rumor has it that the LIBRA experiment, the follow-on to the DAMA experiment, will release results later this week. For those of you not in the know, the DAMA experiment is the only experiment to date to claim a direct observation of a dark matter signature. Models of dark matter suggest that as the earth goes around the sun, and the sun moves through the galaxy, the earth travels in different directions through the dark matter. This would cause an annual variation in the number of dark matter interactions in their detector. Over many years, they observed a period signature (see below). [1]
Problem was, there were no independent experiments that confirmed their results. Experiments like CDMS and XENON, searching for single dark matter scatters off their detectors, have excluded the DAMA result many times over by not observing any dark matter. DAMA collaborators have spent years arguing why their result is right, or at least not in total disagreement with other null measurements. I saw one such impassioned defense at ICHEP 2006 in Moscow.
I say: pony up the data. DAMA stopped taking data years ago, and the same collaboration started construction on a new experiment called LIBRA. LIBRA was meant to make a similar measurement of the annual dark matter modulation. But, they refused to release their results until they had an “exposure comparable to DAMA”.
Tap. Tap. Tap. Well, I’ve been waiting a long time for LIBRA to cough it up, and if the rumors are right then the time is nearly here!
[1] http://www.slac.stanford.edu/spires/find/hep/www?j=PHLTA,B480,23
