Anti-Matter is like matter, but with a opposite
property (spin, charge, etc) that nullify between
them, releasing photons (and neutrinos and
another fancy particles)
Actually, you can collide anything vs anything,
but you need to see the quark composition of the
particles to try to predict the outcome (pretty
hard, cause everything will collide vs
everything, primarly the target ones, next the
newly formed particles, just with fewer
interactions...
from wikipedia
http://en.wikipedia.org/wiki/Antimatter
"In particle physics, antimatter is the extension of the concept of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles. For example, an antielectron (a positron, an electron with a positive charge) and an antiproton (a proton with a negative charge) could form an antihydrogen atom in the same way that an electron and a proton form a normal matter hydrogen atom. Furthermore, mixing matter and antimatter would lead to the annihilation of both in the same way that mixing antiparticles and particles does, thus giving rise to high-energy photons (gamma rays) or other particleâ"antiparticle pairs."
