Particles

Particles

Hadrons
1. have sub-structure (non-fundamental)
  1. Made up of QUARKS
    1. Triplets
      1. 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
    2. Quark Antiquark Pair
      1. 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. 3 Types
      1. UP
        C +2/3
        BN +1/3
      2. DOWN
        C -1/3
        B +1/3
      3. STRANGE
        C -1/3
        BN +1/3
        Strangeness -1
2. Feel the strong nuclear force
Leptons
1. Fundamental particles
2. Lepton number 1
  1. 1 number for each type
3. Six Types + associated antiparticles
  1. Muon
  2. Muon neutrino
  3. Electron neutrino
  4. Electron
  5. Tau neutrino
  6. Tau
4. Don't feel SN force
Bosons
1. exchange particles
  1. carry forces between particles
Atomic structure
1. Atomic number
  1. Total no. of protons in the nucleus
2. Nucleon (mass) number
  1. Total no. of protons and neutrons
3. Isotopes
  1. Same no. protons
  2. Different no. of neutrons
    1. Greater no. neutrons = less stable nucleus
Stability of nuclei
1. electrostattic forces
  1. Replusion of protons
  2. Range indefinite
2. Gravitational forces
  1. weak
3. Strong nuclear (attractive) force
  1. v.short range: few femtometers
  2. Works equally on all nucleons
  3. At v.small separation SN force is replusive
4. Decays
  1. Alpha
    1. v. big nuclei
      1. nuclei to big for SN force to keep stable
    2. When alpha particle emmitted
      1. PN decreases by 2
      2. Mass no. decreases by 4
  2. Beta minus
    1. Neutron rich nuclei
    2. Electron + antineutrino emitted from nucleus
      1. PN increases by 1
      2. Mass no. stays the same
      3. Antineutrino carries away
        energy
        momentum
Particles + antiparticles
1. Antiparticles have
  1. Same mass
  2. Opposite charge
2. Pair production
  1. 2 protons collide at high speed
  2. High energy
    1. Converted into more particles
  3. antiparticles + particles formed
    1. produced from single photon
    2. usually electron positron pairs produced
      1. low mass
      2. curve due to magnetic field
        opposite directions : opposite charges
3. Annihilation
  1. Particle meets antiparticle
  2. Total mass converted into enegy

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	Creado por jhhoward hace más de 10 años