Okay so I have a problem with what my text book is saying. It defined pair production as a process in which a photon of electromagnetic energy is converted to a pair of particles. But then it gave the discovery of an antiproton. Which was when a proton was accelerated to 6MeV and collided into a stationary proton, making one antiproton and 3 protons. So, does this p + p --> p + p + antip process count as pair production? In which case, would the definition of pair production be a bit different? Also, I found a website on which it says that ''sometimes, a pair of particles annihilates, but then the photon produces another pair of particles.'' When it comes the the first line, is this basically when a pair annihilates, but then the photon still has a lot of energy due to the extra kinetic energy of the particle and its antiparticle, meaning that when it passes close to a nucleus? Edit: It also says that a antip + p = n + antin Is this besically an example of what I just wrote above (particles annihilate but then the photon produces another pair of particles)? Sorry for lots of questions and thank you for your time.