基本粒子. 2 The Periodic Table Mendeleev (1869) introduced the periodic table.
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Transcript of 基本粒子. 2 The Periodic Table Mendeleev (1869) introduced the periodic table.
Discovery of Electron• J.J. Thomson found that Cathode rays are electrons
A陽極
O陰極
O’狹縫
CC’平行面板
B
E
C
C’
圖一Pluecher (Germany) found cathode rays in 18581870s 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 AtomsRutherford (1912)showed that atomscontain a centralnucleus
Electrons orbit nucleuswith well-definedenergy and ill-definedpositions10
-10 m
5
The Structure of Nuclei
Nucleus containsprotons with charge+e and unchargedneutrons
10-15
m
J. Chadwick (1932)discovered neutron 2α
4 + 4Be9 6 C12 + 0n
1
6
10-15
m
The Structure of NucleonsNeutrons and protons contain quarks
“Seen” in the deep inelatsticep scattering at SLAC (1967)
7
The Constituents of Matter
Protons contain uud - charge = +eNeutrons contain udd - charge = 0
quarks electron
23
e+
13
e- -e
charge
u
d e
8
Proton Decay?
50000 tons pure water•τp>1035 years (Experiment)
•τp~1036 years (GUT theory)
Super- Kamiokande experiment is 1,000 m underground in Mozumi Mine
11000 photomultiplier tubes
Cherenkov radiatio
n
9
Prediction of Antimatter
Paul Dirac predicted existence of the positron in 1928
Dirac’s equation implies:
positron mass = electron mass
positron charge = +e
12
Antimatter Disappears in a Matter Dominant
World
e+ e-
Inverse process also occurs, electrons and positrons annihilate to produce photons (energy)
E = mc2
13
The Fundamental Particles
u
d
tc
s b
six quarks
1947
1976 1995
1978
e
e
six leptons
1956
1895
1963
1936 1973
Along with their anti-particle partners
Spin ½ fermions
15
A Colorless World
Quarks
Leptons
u c t
d s b
Charge=+2/3
Charge=-1/3
πMeson
Λ Baryon
Mesons: π,ρ,Φ,k,B…
Baryons: p,n,Λ,Σ,Δ…
e μ τ
νμ νe ντ
NeutrinosCharge=0
Charge=-1Mediator
γ G Z0 W ±
?graviton ?graviton
2005/12/9 物理光耀世界 (Ⅱ)- 紀念 1905 物理奇蹟年的一百週年 16
Evolution of the Universe
The Universe began with a “Big Bang” about 15 billion years ago
-270o
?
heavy elements formed in stars
stars and galaxies exist, atoms form
neutrons
quark "soup"
15 billion years
1 million years
1 second
10-10
1015deg 1010deg109deg
6000o
-255o
3 minuteshelium nuclei formed
microwave background radiation fills universe
300,000 years
4000o
life on earth, molecules form
dominates matter
and protons formed
1 billion years
s
Big Bang
Big Bang