Particle Physics

• Specific Charge Equation


  specific charge = charge / mass
• Specific charge unit


  Ckg^-1
• Relative Charge


  overall charge

  e.g. 2+ ion => relative charge of 2
• Specific Charge of Atoms


  is zero because they are neutral due to the balance of protons and electrons
• 4 Fundemental Forces

  • Strong Nuclear Force
  • Electromagnetic force
  • Gravitational force
  • weak interaction
• Force responsible for repulsion by like forces?

  Electromagnetic
• Which force provides attraction in the nucleus

  The strong nuclear force provides attraction between nucleons at appropriate distances
• Exchange Particle of Electromagnetic force 


  Virtual Photon
• Exchange Particle for weak nuclear force


  W boson (+ or -)
• What are exchange particles?

  Exchange particles are responsible for carrying the four fundemental Forces between two interacting particles
• Relative charge of an antineutrinl

  0
• Relative charge of a neutrino

  0
• Relative charge of a positron?

  1
• What happens in alpha decay?


  Emission of an alpha particle, leading to the proton number to decrease by 2 and the nucleon number to decrease by 4
• What happens in beta minus decay? (β-)


  A neutron in the nucleus decays into a proton, electron and electron antineutrino.

  This causes the proton number to increase by one while the nucleon number remains the same
• What happens in beta plus decay? (β+)


  A proton in the nucleus decays into a neutron, positron and an electron neutrino.

  This causes the proton number to decrease by one and the nucleon number to remain the same.
• Why neutrino was hypothesised?

  To account for energy that needed to be conserved
• What is a photon?

  A discrete particle of electromagnetic radiation
• E = hf


  where E is photon energy

  where h is Plancks constant

  where f is frequency
• Relationship between photon energy and frequency?


  Directly proportional
• How convert J to eV

  divide J by the charge of an electron
• photons travel at the speed

  of light in a vacuum
• E=hf can also be written as

  E= (hc)/λ
• p=E/c

  where p is photon momentum

  where E is energy

  where c is speed of light
• What happens during annihilation?

  Particle and its antiparticle collide, they become two photons. this is to conserve energy and momentum
• What does pair production look like?

  high energy photon creates a particle-antiparticle pair

  
• What is rest mass energy?

  The energy a particle has due to its mass, the energy due to being stationary
• What are hadrons?

  Hadrons are particles made of quarks

  • Baryons and mesons are hadrons
• What are leptons


  Fundemental particles
• What does fundemental mean?

  The particle cannot be broken down further as they are not made of other particles
• Baryon number of proton and antiproton

  Proton - 1

  Anti proton- -1
• What is a baryon?

  A hadron made of 3 quarks
• What is a meson?

  A hadron made of a quark-antiquark pair
• Can leptons feel the SNF?

  No.

  They are outside of the nucleus
• Most stable baryon


  Proton
• How does a muon decay?


  Decays into an electron, an electron antineutrino and a muon neutrino
• What is a quark?

  Fundemental that combine to form hadrons
• Proton quark composition

  uud
• Neutron quark composition

  udd
• Composition of a π+ meson


  u (anti)d