Particles & Antiparticles.

Particles & Antiparticles.

1. Photons are packets of Electromagnet radiation

2. Every particle has an antiparticle

   • Proton; charge +1,
   • Antiproton; charge -1
   • Mass; 1.673x10-27 Kg, rest energy 938.3 MeV
   • Neutron
   • Antineutron
   • Charge 0, mass 1.675x10-27 Kg, rest energy 939.6 MeV
   • Electron; charge -1
   • Positron; +1
   • Mass; 9.11x10-31 Kg, rest energy 0.511 MeV
   • Neutrino
   • Antineutrino
   • Charge; 0, mass 0, rest energy 0

3. You can create matter and antimatter from energy

   • Energy can turn into mass & mass can turn into energy
   • When energy is converted into mass you get equal amounts of matter and antimatter
   • 1. Fire 2 protons at each other at high speed and youll end up with a lot of energy at the point of impact.
     • This energy may be converted into more particles
   • 2. If an extra proton is formed then there will always be an antiproton to go with it

4. Each particle-antiparticle pair is produced from a single photon

   • Energy that gets converted into matter & antimatter is in the from of a photon
   • Pair production only happens if one photon has enough energy to produce that much mass- only gamma rays have enough energy
   • Also tends to happen near a nucleus which helps conserve momentum
   • Usually get electron-positron pairs produced because they have a relatively low mass
   • The minimum energy for a photon to undergo pair production is the total rest energyof the particles produced

5. The opposite of pair production is annihilation

   • when a particle meets its antiparticle the result is annihilation
   • All the mass of the particle and antiparticle gets converted back to energy
   • Antiparticles can only exist for a fraction of a second before this happens so you don't get them in ordinary matter
   • An annihilation is between a particle-antiparticle pair, which both have a rest energy
     • Both photons need to have a minimum energy

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