Hello. Where are the anti-particles in a nuclie?Are they virtual particles or are there pair production for every particle-antiparticle? Where do the positron lie in an electron? How does different forms of raditaon account for production of these anti-paricles? For example, how does beta plus decay occur?? I mean how can a positron be emmited?? And how does pair production occur; where does the anti-particle come from or how does it get created?