Radioactive Decay

Types of Radioactive Decay

• Alpha decay: the loss of an α-particle
  • α-particle: a helium nucleus
• Beta decay: the loss of a β-particle
  • β-particle: a high-energy electron
• Positron emission: the loss of a positron
  • Positron: a particle that has the same mass as, but an opposite charge to, that of an electron
• Gamma emission: the loss of a γ-ray
  • γ-ray: high-energy radiation that almost always accompanies the loss of a nuclear particle:
• Electron capture (K-capture): addition of an electron to a proton in the nucleus
  • The result of this process is that a proton is transformed into a neutron

Kinetics of Radioactive Decay

• Nuclear transmutation is a first-order process.
• The kinetics of such a process obey this equation:
  • ln(Nt/N0) = −kt
  • Nt is the mass, or number of particles at time t. 
  • No is the original. 
• The half-life of such a process is
  • 0.693/k=t1/2 
  • Comparing the amount of a radioactive nuclide present at a given point in time with the amount normally present, one can find the age of an object.

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