BRAINCAKELepton Collisions
When a lepton meets its antiparticle they can annihilate. In electron-positron annihilation the mass of the two particles is converted into energy, and the particles created must obey the conservation laws.
At low collision energies the electron and positron produce two gamma photons travelling in opposite directions, so that momentum is conserved. Each photon has a minimum energy equal to the rest energy of an electron, 0.511 MeV.
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Key terms in this lesson
- Photon
- A discrete packet, or quantum, of electromagnetic energy.
- Positron
- The antiparticle of the electron: it has the same mass as an electron but a positive charge.
- Annihilation
- The process in which a particle and its corresponding antiparticle meet and their mass is converted entirely into photon energy.
- Lepton
- A fundamental particle that does not interact through the strong interaction, for example the electron, the muon and their associated neutrinos.
- Hadron
- A particle made up of quarks that interacts through the strong interaction; hadrons are divided into baryons and mesons.
More in Quarks and Leptons
- Leptons
- Hadrons
- Particle Colliders and Energy
- Baryons and Mesons
- Lepton Rules
- Neutrinos
- Strangeness
- The Quark Model
All 17 lessons in Quarks and Leptons · All AQA AS-level Physics topics