Particles, antiparticles and photons

• What is an alpha particle

  A particle that contains two neutrons and two protons, the same as a helium Nucleus
• What is an antiparticle

  For each particle there is a particle with the same rest energy and mass but all other properties are the opposite of its respected particle
• True or false: every particle has an anti-particle

  True
• What is the name of the antiparticle of an electron

  Positron
• What is the antiparticle of π0 (pion with 0 charge)

  itself
• What occurs when a particle and antiparticle meet

  Annihilation: The mass of the particle and antiparticle is converted back into energy in the from of 2 gamma ray photons which go in opposite directions to conserve momentum
• What is pair production

  A gamma ray photon is converted into a particle-antiparticle pair
• What is the minimum energy of a photon required to make a proton-antiproton pair

  2 x proton rest energy