One reason he and his collaborators lean toward a dark matter origin is that the detector gathered positrons from all directions, evenly, without pause. That suggests that they came from something that is omnipresent, such as the theorized dark matter.
A key question is whether the detector finds many positrons at very-high-energy levels. For theoretical reasons, a sudden drying up of positrons at the high-energy end of the scale would be consistent with a dark matter origin. Ting told the scientists that he wasn't ready to release the high-energy data and that they should be patient.
Ting said in a later NASA teleconference that the AMS will collect data through the lifetime of the space station and that he expects to be able to solve, with finality, the mystery of the positrons — "hopefully, quickly."
This will not, however, end the mystery of dark matter. Even if the AMS is a smashing success, it has no ability to discern what dark matter is, fundamentally, or how much of it is out there, or why it is dark.