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Announcements

Announcements. Grade Breakpoint Adjustment Exam 4 Final Exam Multiple choice (16 questions) Problems like problems on midterms Problems from midterms with different numbers. Fusion--Two nuclei combine to form a heavier nucleus. First reaction in early stars

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Announcements

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  1. Announcements • Grade Breakpoint Adjustment • Exam 4 • Final Exam • Multiple choice (16 questions) • Problems like problems on midterms • Problems from midterms with different numbers

  2. Fusion--Two nuclei combine to form a heavier nucleus First reaction in early stars 11H + 11H → 21H + e+ + νe mass before - mass after = energy released/c 2 (2MH1 – 2Me) – (MH2 –Me + Me) = (2x1.0078250u - 0.0005486u) - 2.0141018 u = 0.0009996 u (1uc2=931 MeV) Q = 0.93 MeV

  3. Fusion--Two nuclei combine to form a heavier nucleus More reactions in stars 11H + 11H → 21H + e+ + νe 11H+ 21H → 32He 11H+ 32He → 42He + e+ + νe 32He+ 32He → 42He + 11H + 11H

  4. Fusion--Two nuclei combine to form a heavier nucleus One reaction in a hydrogen bomb 21H + 31H → 42He + n Total mass before -Total mass after = energy released 5.0302 u - 5.0113 u = .0189 u ≈ 17.6 MeV

  5. Fusion Reactors • Much less radioactivity • Mostly produces helium-4, but materials near the reaction can absorb neutrons, etc. • Hydrogen is everywhere! • It doesn’t work . . . Yet • Protons repel each other until you get them really close • Really high temperatures needed

  6. Plasma Fusion

  7. TFTR

  8. Inertial Confinement Fusion

  9. Other practical uses of nuclear physics… • Nuclear medicine • Nuclear treatment (destroy tumors) • Tracer imaging • PET scan • NMR (MRI) ? • Power for space probes • Dating materials • Sterilization of equipment or food • Smoke detectors

  10. Van Dyck’s “Saint Rosalie Interceding for the Plague-Stricken of Palermo” Irradiated with neutrons Detected electrons emitted

  11. After a few hours - manganese (found in umber, A dark pigment)

  12. After 4 days - phosphorous (found in charcoal)

  13. Jackson Pollock – Galaxy Irradiated with neutrons

  14. Jackson Pollock – Galaxy Detected secondary emission of truth

  15. And beyond • Particle physics, QCD, the standard model • Unification theories / theory of everything • String theory

  16. 3 Nephi 12:3 Yea, blessed are the poor in spirit who come unto me, for theirs is the kingdom of heaven. Brothers and sisters, whatever your distress, please don’t give up and please don’t yield to fear. --- Elder Jeffrey R. Holland, General Conference, April 2006

  17. Review Request • deBroglie wavelength for relativistic particle of given Ek

  18. Review Request • Velocity transform

  19. Review • Postulates of Relativity • Time dilation • Length contraction • Lorentz transformations – velocity transform • Relativistic momentum and energy

  20. Review • Photons • Bohr Atom • de Broglie Waves

  21. Review • Notation – atomic number, mass number • Half Life

  22. Review • Nuclear Decay • Gamma • Beta – • Beta + • Ec • Alpha

  23. Review • Fission • Fusion

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