Particle Physics

• What is the Rutherford-Bohr model of the atom?

  Central nucleus with orbiting electrons
• Why is the Rutherford-Bohr model still used despite not being the most accurate?

  It explains almost all atomic behavior
• What is the JJ Thompson model of the atom called?

  Plum pudding model
• What does specific charge refer to?

  Charge per unit mass
• What is the equation for specific charge?

  Q/m
• What does Z represent in atomic terms?

  Proton number
• What does A represent in atomic terms?

  Nucleon number
• What is an isotope?

  Atoms with same protons, different nucleons
• Why do protons not repel each other in the nucleus?

  Strong nuclear force overcomes repulsion
• What is the range of the strong nuclear force?

  Up to 3.0 fm
• What happens to the strong force below 0.4 fm?

  It becomes repulsive
• What occurs at the equilibrium position of nucleons?

  Resultant force on nucleons is zero
• What does beta decay involve?

  Decay of neutron into proton, electron, antineutrino
• What is emitted during gamma decay?

  Gamma ray photon
• What are neutrinos?

  Neutral, almost massless subatomic particles
• What are the three types of neutrinos?

  Electron, muon, tau neutrinos
• Why must neutrinos be emitted during beta decay?

  To conserve total energy during decay
• How do you make a cloud chamber?

  Rapidly expand air saturated with water vapor
• What do wide cloudy tracks in a cloud chamber indicate?

  Presence of alpha particles
• What do thin, straight or curved tracks in a cloud chamber indicate?

  Presence of beta particles
• What do gamma rays produce in a cloud chamber?

  No tracks at all
• How does a cloud chamber detect radiation?

  Clouds form on charged particles
• How does a spark counter work?

  Ionized air particles create visible sparks
• Why can spark counters only detect alpha radiation?

  Beta and gamma are not ionizing enough
• What is an advantage of Geiger-Muller counters?

  Can detect all three types of radiation
• What are the three types of matter and antimatter?

  Leptons, hadrons, exchange particles
• What are exchange particles?

  Virtual particles exchanged during interactions
• Why can virtual particles not be detected?

  Detecting changes their properties
• What are baryons?

  Particles containing three quarks or antiquarks
• What are mesons?

  Particles containing a quark and antiquark pair
• What are hadrons?

  Particles made from quarks
• Which fundamental force do leptons not experience?

  The strong force
• What are leptons?

  Elementary and fundamental particles that include neutrinos, taus, electrons, and muons
• Which leptons are stable?

  Electrons and electron neutrinos
• What is the only stable baryon?

  Protons
• What is the quark configuration of a proton?

  u, u, d
• What is the quark configuration of a neutron?

  u, d, d
• What is the quark configuration of a neutral pion?

  u, ū or d, anti-d
• What is the quark configuration of a negative pion?


  ū, d
• What is the quark configuration of a positive pion?

  u, anti-d