All known matter particles are made of quarks and leptons, and they interact by exchanging force-carrier particles (exchange particles)
Quarks have a fractional electric charge and a colour charge. They are fundamental particles.
- p + p-bar → 2γ
The energy of the 2γ photons comes from the rest energy of the particle and its antiparticle, (e.g. proton rest mass= 938 MeV, so 2γ= 1876 MeV).
- γ→ p + p-bar
When a high-energy photon interacts with a particle, e.g. a neutron, a particle and its antiparticle can be produced if there is enough energy, ie. energy of γ ≥ rest energy of…