8th step - other hints

The darkness of the track depends purely on the velocity of the particle. The slower it is going the more time it has for the Coulomb force generated to interact with the nearby detector electrons and so the more bubbles will be produced. A fast particle will not have time to produce significant effects on the electrons and so it will produce less bubbles and the path will be fainter.

Sometimes you will observe a path that becomes very dark and then disappears. This would indicate a particle gradually slowing down and then stopping.

When the original bubble chamber pictures were taken, two or more photos of the same event were taken, from different angles. This is because the event is happening in 3 dimensions and so just one 2 dimensional picture will not give us all the information we need to understand what is happening.

There are at least two situations in which more than one view of the event is needed to interpret it visually.

When a particle track just stops in the middle of the picture this could be because the particle has stopped or because it has moved into the glass of the bubble chamber window. You can check for this using two pictures by comparing the position of the track with the crosses marked on the glass as reference points. If the path stops in the same place on all the pictures with respect to these points then the particle has moved out of the chamber. If the path stops at a different place with respect to the reference points then the particle has stopped within the chamber.

The second situation in which more than one picture is necessary is when two events seem to happen at the same point in one picture.