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Elementary Particle Physics Microcosmos I. II. III. IV. The Wild World of Subatomic Particles The Story of the Higgs The Mystery of Dark Matter Particle Physics and You! Frank Linde Nikhef & UvA +31-205925001 [email protected] Dark ages Long ago … Empedocles Plato Aristoteles Leucippus Democritus Air Water Fire Earth Atoms 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 Alchemy Lead Gold Number of atoms per volume independent of atom type! (Avogadro) NA atoms = 1 Mole Atoms gas 22.4 liters NA = 6.0221420 1023/Mol How large? 30-3001012 meters How heavy? 2-4501025 kilograms How many? 31023/gram hydrogen Het Periodiek Systeem Periodic Table of Elements nummering: kernlading Nobel gasses Not part of the original Mendeleev periodic table The atom Thomson 1897 e/m = 1.761011 C/kg Thomson 1897 qe = 1.60217646 1019 C me = 9.1093819 1031 kg Millikan 1900 electron Atoms: Rutherford’s view Elementary particles (1932): Electron, Proton & Neutron 1897 electron Thomson 1911 nucleus Rutherford 1911 proton Rutherford 1932 neutron Chadwick Physics just before 1900 ??????? all ok ??????? Done? No: few “minor” problems: “black body” radiation no eather? natural radioactivity (Curie et al.) stability of the Rutherford atom I. Special relativity 1905 Intermezzo: Einstein & relativity Time travel becomes a reality! ‘click’ of the light clock at rest: t L ‘hence-and-forward’ light flash period t: 2L t= c c=299792458 m/s (exact) observer at rest c=299792458 m/s (exact) ‘click’ of the moving light clock: t’ ‘hence-and-forward’ light flash period: t’ v [m/s] L 2L2+(½vt’)2 t’ = c (ct’)2 = 4L2+(vt’)2 t t’ = 2L = t c2v2 1v2/c2 ½vt’ vt’ Moving clock ‘clicks’ slower! observer moving with velocity v II. Quantum world 1900-19 Imagination Light: quantum effects Planck 1900 Planck (1858-1947) Einstein 1905 Einstein (1879-1955) Compton 1922 Compton (1892-1962) I. Black body radiation Planck 1900 Stacking waves! Fit ½, 1, 1½, 2, etc. wavelengths in box such that amplitude=0 on walls L Easier to fit short wavelengths! =2L =1L =½L Light wave's energy: classical energy E continuous! |amplitude|2 ultra-violet catastroph energy density Radiated energy spectrum: classical 0 m ρE λ 0,5 m 8π λ 1 kT 4 wavelength () Light wave's energy: quantum E = Nhf Planck’s constant h = 6.62606881034 J/s E = 5hf E discrete! energy E = 4hf E = 3hf E = 2hf E = hf # quanta N hc ρE λ 4 hc λkT 1 λ λ e ultra-violet catastroph energy density Radiated energy spectrum: quantum 0 m 8π 0,5 m 1 wavelength () Color T=2,500 oC the sun T=5,000 oC T=7,500 oC T=10,000 oC T=12,500 oC T=15,000 oC Universe as black body radiator T 2.725 K 270.5 oC Big Bang’s afterglow on your TV II. Photo electric effect incident light wavelength (frequency f) Einstein 1905 knocked out electrons slab of material III. Compton effect incident light wavelength Compton 1922 scattered light wavelength ’ scattered electron Duality: wave & particle characteristics It is safe to say that nobody understands quantum mechanics. R.P. Feynman Quantum mechanics is magic. Daniel Greenberger. Everything we call real is made of things that cannot be regarded as real. Niels Bohr. Those who are not shocked when they first come across quantum theory cannot possibly have understood it. Niels Bohr. If you are not confused by quantum mechanics, you do not understand it. John Wheeler. more quotes If quantum theory is correct, it signifies the end of physics as a science. Albert Einstein. I do not like quantum mechanics; I am sorry I ever had anything to do with it. Erwin Schrödinger. Atom: quantum effects Bohr 1910 Bohr (1885-1962) Heisenberg Schrödinger 1925 1927 Heisenberg (1901-1976) Schrödinger (1887-1961) Bohr’s atom model En 13.6 n 2 eV n=5 4 3 2 1 n=3 n=2 n=1 Balmer serie En 13.6 n 2 1 1 2 10.97 2 1 n μm1 eV μm 1 3 2 1 Paschen Balmer Lyman 0.0 1.5 3.4 binding energy (eV) 1 1 2 2 10.97 2 n μm 1 quantum number (n) 1 1 2 2 10.97 3 n 13.6 eV Heisenberg’s uncertainty principle 4 /2 t large t small light t [s] light f large f small f [1/s] electron electron Schrödinger’s wave equation 1H ground state n=1 “s” states n=1 n=2 n=3 “p” & “d” states Electron: quantum details Lorentz & Zeeman 1896 (1885-1962) (1887-1961) Leiden Amsterdam Uhlenbeck & Goudsmit 1925 (1887-1961) (1901-1976) Leiden Leiden Pauli 1925 (1900-1958) N Stern Gerlach Z Zeeman N Z Electron Uhlenbeck Goudsmit spin! Democracy: all electrons are equal Pauli: Each electron in a different state! electron = asocial The electron Mass: 0.000000000000000000000000000910938188 gram Electric charge: 0.00000000000000000016021765 Coulomb Mean lifetime: (infinite) seconds ”Spin”: ½ Perfect description of atoms! ‘Physics 2000’ website (Colorado) Relativistic quantum theory Dirac Anderson Feynman Dirac (1902-1984) Anderson (1905-1991) Feynman (1918-1988) 1928 1932 1947 negative energy positive energy Dirac’s anti-matter hypothesis e e+e e e+ + e Anderson’s anti-electron discovery e+e Positron EmissionTomograph Angels & Demons: the movie Real fun: creation & annihilition Compton scattering: e e Möller scattering: e e e e Bhabha scattering: e+ e e+e Pair creation: the only interaction e+e Pair annihilation: time e+e Particle collisions boring collisions exciting collisions high energy fun collisions 2 E=mc large mass Elementary Particle Physics Microcosmos I. II. III. IV. The Wild World of Subatomic Particles The Story of the Higgs The Mystery of Dark Matter Particle Physics and You! Frank Linde Nikhef & UvA +31-205925001 [email protected]
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