What is the direction of the magnetic field?

Pair production is a process that creates a subatomic particle and its antiparticle from a neutral boson. For example, it can create an electron and a positron, a muon and an antimuon, or a proton and an antiproton.  Pair production often refers to a photon creating an electron–positron pair near a nucleus. In this process, a gamma ray of sufficient energy is annihilated in the Coulomb field of a nearby charged particle. This results in the creation of an electron–positron pair.  Pair production is the opposite of annihilation. It is a direct conversion of radiant energy to... Show more

Pair production is a process that creates a subatomic particle and its antiparticle from a neutral boson. For example, it can create an electron and a positron, a muon and an antimuon, or a proton and an antiproton. 
Pair production often refers to a photon creating an electron–positron pair near a nucleus. In this process, a gamma ray of sufficient energy is annihilated in the Coulomb field of a nearby charged particle. This results in the creation of an electron–positron pair. 
Pair production is the opposite of annihilation. It is a direct conversion of radiant energy to matter. 
Blackett and Giovanni P. S. Occhialini discovered pair production in 1933 by taking photographs of electrons and positrons created from cosmic rays in a Wilson cloud chamber. 

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