How Cosmic-ray Protons Make Gamma rays

  • Released Saturday, February 13th, 2010
  • Updated Wednesday, May 3rd, 2023 at 1:54PM
  • ID: 10567

In the simplest and most common interaction, a cosmic-ray proton strikes another proton. The protons survive the collision, but their interaction creates an unstable particle — a pion — with only 14 percent the mass of a proton. In 10 millionths of a billionth of a second, the pion decays into a pair of gamma-ray photons. More complex scenarios occur when cosmic-ray protons strike nuclei containing greater numbers of particles.

Simple animation of proton-proton interaction resulting in netural pion that decays into two gamma rays.

This animation shows a more dynamic view of the pion and gamma ray creation process.

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NASA/Goddard Space Flight Center

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