4.42 Antimatter

• The universe is made up of matter particles (protons, neutrons, electrons etc.)
• All matter particles have antimatter counterparts
  • Antimatter particles are identical to their matter counterpart but with the opposite charge

• This means if a particle is positive, its antimatter particle is negative and vice versa
• Common matter-antimatter pairs are shown in the diagram below:

This table summarises the electric charge for typical particle-antiparticle pairs

• Apart from electrons, the corresponding antiparticle pair has the same name with the prefix ‘anti-’ and a line above the corresponding matter particle symbol
• A neutral particle, such as a neutron or neutrino or photon, is its own antiparticle

Mass of Matter & Antimatter

• Although antimatter particles have the opposite charges to their matter counterparts, they still have identical mass and rest mass-energy
  • The rest mass-energy of a particle is the energy equivalent to the mass of the particle at rest

This table summarises typical particle-antiparticle pair masses and rest mass energies