A Cosmic Connection!

This is a side-show in a small corner of a picture taken in the 15-foot bubble chamber, filled with a mixture of neon and hydrogen, and exposed to a high energy neutrino beam. It has nothing at all to do with neutrinos!

The event we will investigate is cradled between two thick tracks caused by cosmic rays that happened to enter the bubble chamber while it was active. The knock-on electron on the straighter cosmic ray, which is entering the picture from the top, tells us that negative particles turn to the left.

The event is caused by an incoming hadron (or strongly-interacting particle, probably a pion ). There are three outgoing charged particles; to the left of the event, a photon , probably from the decay of a materialises in the field of a nucleus giving an pair pointing back to the primary interaction; downstream is another such pair.

Slightly downstream of the primary interaction there is a V-shaped secondary interaction consisting of two protons knocked out of a neon nucleus by a neutral particle, probably a neutron from the primary interaction. To the right, an pair points back to this secondary interaction, suggesting that a was produced in the secondary interaction.

One of the protons from this secondary interaction scatters from another, giving two short stopping protons.

Several unmentioned further pairs add to the attractiveness of this picture.