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Nuclear Physics

Nuclear Physics . PHY 361 2008-04-21. history structure of the nucleus nuclear binding force liquid drop model shell model – magic numbers binding energy chart of nuclides line of stability, drip line, island of stability radioactivity  ,  ,  decay fission, fusion. Outline.

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Nuclear Physics

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  1. Nuclear Physics PHY 361 2008-04-21

  2. history structure of the nucleus nuclear binding force liquid drop model shell model – magic numbers binding energy chart of nuclides line of stability, drip line, island of stability radioactivity ,, decay fission, fusion Outline

  3. History • Becquerel – discovered radioactivity (1896) • Rutherford – nuclear model • classified ,, radiation,  particle = 4He nucleus • used  scattering to discover the nuclear model • postulated ‘neutrons’ A=Z+N (1920); bound p+ e- state? • Mosley – studied nucleus via X-ray spectra • correlated (Z = charge of nucleus) with periodic table • extra particles in nucleus: A = Z + ? • Chadwick – discovered neutron (1932) • Pauli – postulated neutral particle from -decay (1930) • Fermi – theory or weak decay (1933) ‘neutrino’ • Fission – Hahn, Strassmann, (&Meitner!) (1938) • first reactor (chain reaction), Fermi (1942) • Bohr, Wheeler – liquid drop model • Mayer, Jensen – shell model (1949) • Hofstadter – electron scattering (1953-) • measured the charge density of various nuclei • discovered structure in the proton (not point-like particle)

  4. strong force + Coulomb repulsion (p-p) ~ finite square potential hard core – const. density Nuclear potential Hofstadter, electron scattering

  5. constant density like a liquidR = R0 A1/3 where R0 ~ 1.2 fm = A / (4/3 R3) = 1014 g/cm3 ! finite square potential p,n act as free particles inside of drop states filled to Fermi energy ‘surface tension’ normally prevents breakup excitation can induce split into smaller drops with lower overall energy Liquid drop model of the nucleus

  6. 1949 – M. Mayer, J.H.D. Jensen similar to atomic orbitals quantized angular momentum energy levels multi-particle wave function difference: no ‘central’ potential (nucleus) effective finite square potential complicated nuclear force strong dependence on spin two particles: p, n more types of decays Shell model of the nucleus nucleus atom

  7. AZXNq ex. 1H, 2H, 3He, 4He A = Z + N = # protons + # neutrons B = Z MHc2 + N mnc2 - MAc2 nuclides – Z,N isotope – constant Z (‘same place’) isotone – constant N (isoto‘n’e) isobar – constant A (‘same weight’) isomer – excited state or nuclide Chart of Nuclides – binding energy

  8. Chart of Nuclides – lifetime magic numbers http://www.nndc.bnl.gov/chart

  9. Chart of Nuclides – decay mode magic numbers stable nuclide - decay , electron capture decay p decay n decay spontaneous fission http://www.nndc.bnl.gov/chart

  10. Chart of Nuclides – island of stability magic numbers http://en.wikipedia.org/wiki/Island_of_stability

  11. ++ decay - decay (isobar) + decay (isobar)  electron capture (isobar) p decay (isotone) n decay (isotope)  decay (isomers) electron conversion (EC) spontaneous fission (SF) double beta decay (2) neutrino-less double beta decay (0) beta-delayed n,p, decay Nuclear decay modes: ISOTONES ISOBARS ISOMERS ISOTOPES Z N

  12. Alpha-decay

  13. Beta-decay

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