At least a local excess of matter became the stars and galaxies we see. Antimatter particles from these galaxies could theoretically move in trajectories around intergalactic magnetic field lines, bouncing from one galaxy to another, slowly making their way toward Earth, needing only the right detector to make their presence known. Scientists are hoping the AMS is that detector. AMS will measure the charge and direction of incoming particles and the amount of their deflection. When particles enter the detector's magnetic field created by a cylinder-shaped shell of magnets, they can be identified by their trajectories.
Electrons are bent in one direction while protons and positrons veer off the other way.
You can tell a positron from a proton because the heavier proton will travel in a straighter path than a positron with the same velocity. This starts the readout of the silicon microstrip tracker, made up of 1,921 silicon sensors in six layered horizontal plates. The aerogel threshold Cerenkov counter enhances the detector's ability to identify particles. As particles pass through a 10-centimeter layer of aerogel, they are viewed by 168 phototubes. This will identify positrons and help distinguish antiprotons from other particles.