陽電子/正電子, Positron, the anti-matter of electron, all of the physical properties of positronis the same as electron, except it is positve charge.
Positron is discovered in high energy experiment, particles are accelerated to near the speed of light, and then hit a target. Positron and other anti-matter are created. The properties of the anit-particles/matter is the same as its particles/matter, except the charge. When particle and anti-particle come together, they will be disappear and become energy, mainly in light (photon).