Particles and antiparticles

Antiparticle: A particle with the same rest energy but with the opposite charge as its corresponding particle. Other properties are also reversed, such as lepton number and baryon number.

every particle has a corresponding antiparticle, apart from the neutral pion which is its own antiparticle.

gamma ray

electron

positron

Pair production: energy is converted into mass, and a particle-antiparticle pair is produced. The mass of the particle is dependent on the frequency of the gamma ray (E=hc/λ) due to equivalence of mass and energy.

Annihilation: a particle meets its antiparticle and the mass of the two particles get converted back into energy.

any number of gamma rays can be produced apart from one, as momentum must be conserved

the frequency of the emitted gamma rays depends on the mass of the pair.

antiparticles can only exist for a fraction of a second before annihilation, so they don't exist in everyday matter.

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