Charge conservation

Charged particles that travel far enough to be seen in the bubble chamber have a charge that is equal or opposite to that of the proton.This makes checking charge conservation in high energy processes a matter of simple counting.

From the physics point of view we need to know that:

Look at the following picture in which a beam of K- particles enters the CERN 2-metre bubble chamber, filled with liquid hydrogen. (VG: gal02_015 picture only)

Verify that there is one collsion and that charge is conserved.

Verify that there is one decay, and what is the charge of the decaying particle?