Highly energetic γ -photons can sometimes transform their energy, by a process called pair production, into a proton and an anti-proton. The mass of a proton is 938 MeVc−2 .
a. a Calculate the minimum energy, in joules, of a gamma-ray photon that will be able to produce a proton–anti-proton pair.
b. b i Why is it most likely that a proton–anti-proton pair will only be produced by a gamma-ray photon with significantly more energy than your answer to part a?
c. ii What happens to the extra energy that the photon had if a proton–anti-proton pair is produced?