AS Physics Particles and Radiation

AS Physics Particles and Radiation

1. Atomic Structure

   • 1x10-10m in diameter
   • nucleus = protons and neutrons
     • Z = proton number (atomic number)
     • A = nucelon number
   • Atomic number = num of nucleons
   • Isotopes
     • Atoms of the same element with diff num of neutrons
   • Mass number = num protons + num of neutrons

2. Stable/Unstable Nuclei

   • Strong nuclear force keeps nucleus stable
     • Repulsion
       • Below 0.5fm
     • Attraction
       • Between 0.5 to 3fm (1x10^-15m)
   • Alpha decay and Beta Decay

3. Particles and antiparticles

   • Electron : Positron
   • Neutron : Antineutron
   • Proton : Antiproton
   • Neutrino : Antineutrino
   • MeV (Charge and rest energy)
   • EM radiation
     • Emitted in energy "packets" = quanta
       • Photon = quantam of energy of EM radiation
         • E = hf = (hc/λ)

4. Particle interactions

   • Feynman Diagram
     • β+ decay
     • β– decay
     • Electron capture
     • Electron-proton collisions
     • Neutrino-netron collision
     • Antineutrino-proton collision
   • Gravity
     • exchange of gravitons
   • EM Force
     • Virtual photons = the exchange particals (bosons) that carries the EM force between particles
       • Particles with electric charges can attract or repel by exchanging virtual photons
   • Strong nuclear force
     • exchange of gluons
   • Weak nuclear force
     • W+ and W– exchange

5. Classifications of Particles

   • Hardons (heaviest)
     • Mesons
     • Baryons
       • Antibaryons
     • QUARKS (not fundamental) Strong nuclear force
   • Leptons (lightest)
     • Weak nuclear force
       • electron, muon, nuetrino

6. Quarks and Antiquarks

   • Baryons = 3 quarks
     • proton = uud
     • neutron = udd
     • antiproton = u'u'd'
     • antineutron = u'd'd'
   • Mesons = 2 quarks
     • Pion: π+(ud), π-(u'd), π0(uu')
     • Kaon: K+(us'), K-(u's), K0(ds')
   • Conservation laws for particle interactions
     • Number before interaction must equal number after interaction
       • Charge
       • Baryon number
       • Lepton number
       • Strangeness

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