we studied that antimatter can be stored in the large hadron collider. what i dont get is that the collider is used to collide particles and antiparticles together right? so how is antimatter stored in the collider without it interacting with the accelerating matter and causing pair production? also in our book its written that the particles are accelerated to such high speeds to increase their mass. why would you need to increase mass if you're simply colliding two types of particles?