Mapa mental

Particles

jhhoward Physics A Levels Inglês

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Particles

Hadrons
- have sub-structure (non-fundamental)
  - Made up of QUARKS
    - Triplets
      - Baryons
        Protons
        2 Up Q
        1 Down Q
        Only stable baryon
        All baryons decay to protons
        Neutrons
        decay into protons
        Antibaryons not found in ordinary matter
        Baryon no. in particle interactions never changes
    - Quark Antiquark Pair
      - Mesons
        Unstable
        BN = 0
        Pions
        lightest
        discovered in cosmic rays
        Produced in high energy particle collisions
        Kaons
        Heavier
        More unstable than pions
        Interact with baryons via strong interaction (force)
    - 3 Types
      - UP
        C +2/3
        BN +1/3
      - DOWN
        C -1/3
        B +1/3
      - STRANGE
        C -1/3
        BN +1/3
        Strangeness -1
- Feel the strong nuclear force
Leptons
- Fundamental particles
- Lepton number 1
  - 1 number for each type
- Six Types + associated antiparticles
  - Muon
  - Muon neutrino
  - Electron neutrino
  - Electron
  - Tau neutrino
  - Tau
- Don't feel SN force
Bosons
- exchange particles
  - carry forces between particles
Atomic structure
- Atomic number
  - Total no. of protons in the nucleus
- Nucleon (mass) number
  - Total no. of protons and neutrons
- Isotopes
  - Same no. protons
  - Different no. of neutrons
    - Greater no. neutrons = less stable nucleus
Stability of nuclei
- electrostattic forces
  - Replusion of protons
  - Range indefinite
- Gravitational forces
  - weak
- Strong nuclear (attractive) force
  - v.short range: few femtometers
  - Works equally on all nucleons
  - At v.small separation SN force is replusive
- Decays
  - Alpha
    - v. big nuclei
      - nuclei to big for SN force to keep stable
    - When alpha particle emmitted
      - PN decreases by 2
      - Mass no. decreases by 4
  - Beta minus
    - Neutron rich nuclei
    - Electron + antineutrino emitted from nucleus
      - PN increases by 1
      - Mass no. stays the same
      - Antineutrino carries away
        energy
        momentum
Particles + antiparticles
- Antiparticles have
  - Same mass
  - Opposite charge
- Pair production
  - 2 protons collide at high speed
  - High energy
    - Converted into more particles
  - antiparticles + particles formed
    - produced from single photon
    - usually electron positron pairs produced
      - low mass
      - curve due to magnetic field
        opposite directions : opposite charges
- Annihilation
  - Particle meets antiparticle
  - Total mass converted into enegy