Particle physics

• Neutrinos


  Particle with neutral electric charge and nearly negligible mass
• Ion


  A charged atom (positive or negative)
• Neutron


  Particle with no electric charge± same mass as proton
• Electron


  Particle with a negative electric charge
• Proton


  Particle with a positive electric charge
• Nucleon


  A proton or neutron
• Nucleus (nuclei)

  Positively charged central core of an atomConsists of protons, neutrons and is dense
• Positrons


  Particle with same mass as an electronPositively charged
• Antineutrinos


  Particle with same mass as neutrino but opposite charge
• Random decay


  Rate of decay of the nucleus has constant probability and is affected by external factors such as temperature, pressure, etco Graph will have fluctuations
• Spontaneous decay


  Rate of decay of the nucleus is not affected by external factors such as temperature, pressure, etco Graph will have same shape at different properties
• Radioactive decay

  When the nucleus emits alpha-, beta-particles and/or gamma-rays to achieve eventual stabilityo Proton + nucleon number & mass-energy conserved
• Strong nuclear force


  Force that acts between quarks and holds the nucleus together; acts over short distances
• Beta-plus decay


  Proton → Neutron + (+1)e
• Beta-minus decay

  Neutron → Proton + (-1)e
• Isotope

  Atoms of the same element with different number of neutrons and same number of protons
• Antimatter


  Particles of same mass but opposite charge
• Leptons


  Fundamental particles (electrons) that are not affected by the strong nuclear force
• Hadrons


  Composite particles that are affected by strong nuclear force and contain quarks
• Mesons


  Hadron: quark-antiquark pairs
• Baryons


  Hadrons: 3 quarks (protons and neutrons)
• Antibaryons

  Hadron: 3 antiquarks
• Alpha particles have a mass of 4u and a charge of +2e. They have high ionizing power but low penetration and can thus be stopped by several cm of air. They are released from the nucleus when the nucleus becomes too heavy.
• Neutrinos have zero rest mass and zero charge. They interact only through weak nuclear forces so they pass straight through matter with little interaction. They are emitted during beta decay.
• The conservation laws state that energy is conserved, momentum is conserved, angular momentum is conserved, charge is conserved and baryon number is conserved.
• Gamma rays have no rest mass or charge, and travel at the speed of light. They are produced as electromagnetic radiation when an atom is excited to a higher energy state. Gamma rays are absorbed by atoms which then emit lower energy photons until all excess energy has been lost.
• Energy is conserved because there is no net change in total energy in any process or reaction. Energy cannot be created nor destroyed; it can only be transferred between different forms.
• Electrons have negative charge and spin. Electrons orbit around the nucleus of an atom. When an electron jumps between two different energy levels it releases energy in the form of a photon. This process is called emission spectroscopy.
• Protons have positive charge and spin. Protons make up most of the mass of an atom. A proton is made up of three quarks - one 'up' quark and two 'down' quarks.
• Charge is conserved because the sum of charges before and after a reaction must always equal zero. Charges can neither be created nor destroyed.
• Beta minus decay occurs when a neutron decays into a proton, releasing an electron and an antineutrino. The equation for this type of radioactive decay is n → p + e- + v¯
• The conservation laws apply to all interactions between subatomic particles. The total number of protons and neutrons must remain constant in any reaction involving hadrons. In addition, the total electric charge remains constant.
• In beta plus decay, a proton inside an unstable nucleus changes into a neutron, emitting a positron and neutrino. The equation for this type of radioactive decay is p → n + e+ + v
• When a particle undergoes alpha decay, it loses four units of atomic mass and two units of nuclear charge. It also loses two units of angular momentum.
• When a particle undergoes beta minus decay, its atomic number increases by one as a result of gaining an extra proton. Its mass number stays the same as there has been no change in the number of neutrons or protons.
• The four fundamental forces are strong nuclear force, weak nuclear force, electromagnetic force, and gravitational force
• Quarks


  Fundamental particles that make up hadrons
• Hadrons


  Particles made of quarks
• Up Quark


  Type of quark with charge 2/3
• Down Quark


  Type of quark with charge -1/3