A positron (or antielectron)is made to stop in a sample of matter.Soon after,how many gamma rays are observed with what energy each?

Question

Quizplus · Accepted Answer

When a positron meets an electron, they annihilate to produce gamma rays with energy equal to the total mass energy of the electron-positron pair, which is 1.022 MeV. Since the positron has a mass of 0.511 MeV/c², its rest energy is equivalent to a gamma ray of 0.511 MeV. Therefore, when a positron stops in matter, it annihilates with an electron in the sample producing two gamma rays of 0.511 MeV each.

A Positron (Or Antielectron)is Made to Stop in a Sample