Alpha Particles

Alpha particles

  • They are helium-4 nuclei, He42
  • Mass: 6.6464835 x 10-27kg
  • Charge: +2e
  • Positively charged, hence deflected by an electric field
  • Deflected by a strong magnetic field
  • Have high ionising power (able to remove electrons from nearby atoms/molecules very effectively), producing a large number of ions(~ 103 to 104) along its path
  • Range of alpha particles in air is about 3-4 cm. Easily stopped by a piece of paper.
  • Cause substances like zinc sulphide to fluoresce and also blacken photographic plates

Alpha decays can be represented by the following equation:

$P_{Z}^{A} \rightarrow D_{Z – 2}^{A – 4} + He_{2}^{4}$, where

  • P is the parent nuclide
  • D is the daughter nuclide


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