The source of any positive sighting in DAMA has to come from the annual modulation in the WIMP signal. The galaxy is sitting in a big cloud of WIMPs and the Solar System is moving through this cloud. However, since the Earth moves around the Sun, at one point in the year it will be heading in the same direction as the Sun and 6 months later it will be heading in the opposing direction. This is a bit like sticking your hand out of the window of a moving car; you feel the oncoming air, and when you push your hand in the same direction in which the car is traveling you feel it more, and moving it in the opposite direction you feel it less. Unlike other experiments, such as CDMS and XENON, DAMA does not distinguish particles on an event-by-event basis. They instead count the number of particles hitting their detectors (a bit like measuring the strength of the incoming wind to use my analogy). The thing is, this does not tell you the nature of the particles you see, nor does it tell you the source of them. They have a huge mountain to overcome to show, with reasonable doubt, that the changing signal is WIMPs and not something else. The changing signal peaks in June and is lowest in December, and there are many other possible sources for the variation, which is only 1.5% in size.