At the colliders, positrons and electrons are accelerated at MeV, GeV levels on their way to making head-on collisions. Various Bosons can be produced. The most discussed type seems to be the two Gamma Photons (511 keV). Question #1: What happens to the XS energy of the positrons and electrons after they have been "converted" into the two gamma photons? When I use SLAC's EGS software which has an upper limit of 200 MeV for accelerating positrons, I use liquid hydrogen as the target and look at the results, which include gamma ray emission, electron emission and positron scattering, but none of the other possible bosons. I have used as few as 10 positrons and the max of 100 positrons in the simulation, but I see only about a 10% production of gamma rays. Question #2. What am I overlooking?