Particle Physics Facts

  • Apart from the three basic, stable particles of atoms – electrons, protons and neutrons – scientists have found over 200 rare or short-lived particles. Some were found in cosmic rays from space; some appear when atoms are smashed to bits in devices called particle accelerators.
  • Every particle also has a mirror-image anti-particle. Although antimatter maybe much rarer, it is every bit as real.
  • Cosmic rays contain not only electrons, protons and neutrons, but short-lived particles such as muons and strange quarks. Muons flash into existence for 2.2 micro-seconds just before the cosmic rays reach the ground.
  • Smashing atoms in particle accelerators creates short-lived high-energy particles such as taus and pions and three kinds of quark called charm, bottom and top.
  • Particles are now grouped into a simple framework called the Standard Model. It divides them into elementary particles and composite particles.
  • Elementary particles are the basic particles which cannot be broken down into anything smaller. There are three groups: quarks, leptons and bosons. Leptons include electrons, muons, taus and neutrinos. Bosons are ‘messenger’ particles that link the others. They include photons and gluons which ‘glue’ quarks together.
  • Composite particles are hadrons made of quarks glued together by gluons. They include protons, neutrons and ‘hyperons’ and ‘resonances.
  • To smash atoms scientists use particle accelerators, which are giant machines set in tunnels. The accelerators use powerful magnets to accelerate particles through a tube at huge speeds, and then smash them together.
  • Huge detectors pick up collisions between particles.