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Nuclear Physics

This comprehensive overview of nuclear physics explores the nature of radiation, focusing on detecting charged radiation and decay mechanisms, including alpha and beta decay. Discover the significance of the decay constant (λ) and decay rate (R), essential concepts in understanding radioactive materials. The phenomenon of carbon dating, using C-14, reveals how these principles apply to dating organic materials by measuring decay. We also discuss the implications of radiation exposure, types of radiation effects, and applications in cancer treatment and imaging technologies like MRI.

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Nuclear Physics

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  1. Nuclear Physics Final – Tues 7-10 PM Bring ID

  2. Radiation

  3. Is radiation charged?

  4. Detecting radiation (charged)

  5. Fig 44-13a, p.1459

  6. decays – a picture

  7. The Decay Constant • The rate at which a decay process occurs is proportional to the radioactive nuclei present in the sample • λ is called the decay constant and determines the rate at which the material will decay • N is the number of undecayed radioactive nuclei present • No is the number of undecayed nuclei at time t=0 half-life

  8. Decay Rate • The decay rate, R, of a sample is defined as the number of decays per second • Ro = Nol is the decay rate at t = o • The decay rate is often referred to as the activity of the sample

  9. Decay Mechanisms

  10. alpha decay

  11. beta decay

  12. The neutrino and the weak interaction A neutron changes Into a proton and electron and neutrino

  13. gamma decay

  14. Changing elements “turning lead into gold” Fig 44-17, p.1465

  15. Carbon Dating • Beta decay of C-14 is used in dating organic materials • The process depends on the ratio of C-14 to C-12 in the atmosphere which is relatively constant • When an organism dies, the ratio decreases as a result of the beta decay of the C-14

  16. A piece of charcoal of mass 25 g is found in the ruins of a city. The sample shows a Carbob-14 acctivity of 250 decays/min. How long has the tree from which the charcoal came been dead. • Half life of carbon-14 is 5730 yr • Fraction of Carbon-14 to Carbon-12 is 1.3x10-12

  17. RADS REM and RBE 1 rad=.01 J/kg of absorbed energy by tissue rem=rad x RBE

  18. Acute Radiation Exposure Effects of Large, Whole-Body Radiation Doses

  19. How much radiation do we get?

  20. Cancer treatment 30 rads

  21. radiation treatmentlinear accelerator

  22. Tracers

  23. Food Fig 45-23, p.1503

  24. NMR (MRI)

  25. MRI

  26. Fig 44-21, p.1469

  27. Tumor

  28. A nucleus of an element has to have a specific charge, but can vary in the number of a. protons. b. neutrons. c. neutrons plus electrons. d. electrons. e. protons plus electrons.

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