Part $2-$ Cloud Chamber Analysis

Bubble chamber pictures were used to identify many of the currently known subatomic particles. Only electrically$-$charged particles leave tracks, by ionizing the liquid in the chamber and leaving a fine trail of bubbles in the photo. The curvature of these particles in the magnetic field can be used to determine their charges and momenta.

Electrons can be produced in different ways: two involve in the production of electrons by the electrically$-$neutral photon, that does not leave a track in the image. These particles appear to be produced from nothing!

Compton electrons are knocked out of atoms by photons, and appear on the bubble track as an isolated, spiraling particle.

Electron$-$positron pair production occurs when a photon converts into an electron and its positively$-$charged antiparticle, a positron. This results in a pair of spiraling tracks in opposite directions.

In this image, the magnetic field was oriented out of the plane of the page. How many tracks in this image were likely to have been made by electrons? Circle them!