基本粒子 - PowerPoint PPT Presentation

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基本粒子
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基本粒子

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  1. 基本粒子

  2. The Periodic Table Mendeleev (1869) introduced the periodic table 2

  3. Discovery of Electron J.J. Thomson found that Cathode rays are electrons O’狹縫 C B O陰極 C’ E A陽極 CC’平行面板 圖一 Pluecher (Germany) found cathode rays in 1858 1870s Crookes (British) studied this extensively ·all metals ·-charge turn in magnetic field Like X-rays (Hertz, etc.) ·unaffected by e-field· can penetrate Al foil 3

  4. The Structure of Atoms Rutherford (1912) showed that atoms contain a central nucleus Electrons orbit nucleus with well-defined energy and ill-defined positions 10-10m 4

  5. The Structure of Nuclei 10-15 m J. Chadwick (1932) discovered neutron 2α4 + 4Be9  6 C12 + 0n1 Nucleus contains protons with charge +e and uncharged neutrons 5

  6. The Structure of Nucleons Neutrons and protons contain quarks “Seen” in the deep inelatstic ep scattering at SLAC (1967) 10-15m 6

  7. The Constituents of Matter charge quarks electron u e 2 3 e + 1 3 e - d -e Protons contain uud - charge = +e Neutrons contain udd - charge = 0 7

  8. Proton Decay? Super- Kamiokande experiment is 1,000 m underground in Mozumi Mine 11000 photomultiplier tubes Cherenkov radiation 50000 tons pure water • τp>1035 years (Experiment) • τp~1036 years (GUT theory) 8

  9. Prediction of Antimatter Paul Dirac predicted existence of the positron in 1928 Dirac’s equation implies: positron mass = electron mass positron charge = +e 9

  10. Discovery of Antimatter Anderson (1932) discovered the positron predicted by Dirac 10

  11. Production of e+e- Pairs e e - + High energy g-ray becomes an electron-positron pair E = mc2 11

  12. Antimatter Disappears in a Matter Dominant World e e + - Inverse process also occurs, electrons and positrons annihilate to produce photons (energy) E = mc2 12

  13. The Fundamental Particles ne nm nt c t u 1956 1963 1976 1995 e m t s b d 1895 1936 1973 1978 1947 six leptons six quarks Spin ½ fermions Along with their anti-particle partners 13

  14. Basic Interactions 14

  15. A Colorless World Quarks Leptons Charge=+2/3 ΛBaryon u c t πMeson Mesons: π,ρ,Φ,k,B… Baryons: p,n,Λ,Σ,Δ… s d b NeutrinosCharge=0 Charge=-1 Charge=-1/3 e μ τ ντ νμ νe Mediator γ Z0 W ± G ?graviton 15

  16. Evolution of the Universe life on earth, 15 billion years molecules 1 billion years form heavy elements 1 million years stars and formed galaxies 300,000 years in stars exist, microwave background atoms 3 minutes radiation form helium fills universe nuclei 1 second formed neutrons and protons - quark "soup" 10 10 s formed matter dominates ? 10 15 deg 10 10 deg Big Bang Big Bang 10 9 deg o 6000 o 4000 o -255 o -270 The Universe began with a “Big Bang” about 15 billion years ago 2005/12/9 物理光耀世界(Ⅱ)-紀念1905物理奇蹟年的一百週年 16

  17. Discovery of Parity Violation ne Co60 B field e- C.S. WU In 1957 Madame Wu measured the asymmetry in the beta decay rate of Co60 and found parity was maximally violated 17