[Cboldt]

I thought cosmic rays were protons. Seems you could deflect them with an electric or magnetic field.

Cosmic rays are high energy photons. "Light" of a higher frequency (and hence more energetic) than X-ray.

[DBrow]

Cosmic rays are high energy photons.

Cosmic rays are mostly atomic nuclei stripped of electrons and zooming along at very very high energies.

There are some photons, they've measured some really energetic ones, but for your garden variety cosmic think of a silicon or iron nucleus.