Radiation

1
Radiation

• What is it?

2
Electromagnetic Radiation

• Radiation resulting from excitation of electrons
• Electromagnetic Spectrum
• Energy is radiated in numerous levels (frequency
  and wavelength) that can be detected
• Nucleus is not involved

3
Nuclear Radiation

• Nuclear means of the nucleus
• Natural radioactivity results from instability in
  the nucleus
• Nucleus is made up of protons and neutrons
• Protons are positively charged, trying to repel
  each other
• Nucleus is held together by the Strong Nuclear
  Force
• Very powerful, able to overcome repulsion, but
  only the size of a nucleus

4
Nuclear Radiation II

• All elements with atomic number above 82 (lead)
  are naturally unstable and radioactive
• They seek stability, and eject high energy
  particles and energy that can be detected.
• Nuclear radiation is spontaneous and irreversible
  (one-way, one-time event)

5
Detecting Nuclear Radiation

• Fogs photographic film (how was first discovered)
• Affects Geiger counter
• Affects other detector types

6
Types of Radiation

• Alpha particles (a) 2 p and 2 n
• A helium nucleus
• Emission of an alpha particle changes the
  identity of the atom
• 92U ? a 90Th
• Alpha particles can be detected by the Geiger
  counter

7
Alpha Particle Radiation

• Least powerful type of radiation
• Can be stopped by paper or skin
• Dangerous if inhaled or swallowed
• (lungs and GI tract have no skin)
• Causes ionization of atoms which make up cells
• If particle attacks cell nuclei, can cause change
  in genetic information (mutation)
• Can cause rapid undifferentiated growth of cells
  (tumors)