Antimatter (Edexcel International A Level (IAL) Physics): Revision Note

Properties of 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

• Some neutral particles, such as the photon, are their own antiparticle

  • This is not true of all neutral particles — the antineutron and the antineutrino are distinct from the neutron and the neutrino

Mass of Matter & Antimatter Particles

• 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