01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10
Classifying collisions - number of neutral particles
Neutral particles do NOT
leave trails of bubbles (because bubble formation is initiated by the ionisation
of the hydrogen atoms by the Coulomb interaction).
However, an unstable neutral particle may decay in the bubble chamber
into a pair of lighter particles - one positive and one negative - leaving
an easily recognisable letter V (or vee) shape. (Click on picture and move cursor 
over active
area A).
If the tracks from the vee happen to cross again, downstream, the line joining the crossing position to the decay position (the V) points back to the origin of the neutral particle. (For details, click here.)
So
our neutral decay vee can be seen to be coming from the collision
and not from the kink.
(Many such decaying neutral partciles leave the bubble chamber before decaying - more in step 8.)