Background

Cosmic rays are radiation that impinges upon the earth. Before hitting the atmosphere the radiation is composed of stable particles: protons, electrons, neutrinos and photons.

Historically the term Cosmic Rays means charged particles incident on the upper atmosphere. Now experiments focus on all radiation with photons and neutrinos being of great importance.

The source of this radiation can be:

• local - the sun

• close - our own galaxy

• distant - anywhere in the Universe

Cosmic rays get their energy from very energetic sources where nuclear fusion is taking place or extreme physics related to such objects as supernovae and black holes.

 

From talk "Cosmic Rays Part 2" by David Miller, 7/20/2007.