5th step - identification of particles from a collision by their decays

We have seen how an unstable neutral particle can be identified via its decay into two oppositely charged particles.

An unstable charged particle may also decay - usually into a charged particle of the same sign and a neutral particle. This shows up in the bubble chamber as a kink - a sudden change into a more curved track (move cursor above the picture).

Notice that one of the positive tracks kinks twice, ending up with a positive spiralling track (incidentally produced anti-electron e+).

The number of unstable particles that travel far enough to decay in the bubble chamber is limited. They leave characteristic decay signatures that enable the parents to be identified.