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Summary and conclusions

The beauty of bubble chamber pictures is that they provide detailed pictures of the motion of any charged particles that have appeared in a bubble chamber as a result of an interaction between an incoming beam particle and a nucleus of an atom in the liquid. The tracks we see are trails of bubbles caused by ionization. The momenta of these charged particles are obtained by measuring the curvatures of the tracks. If the particles stop in the bubble chamber, their ranges (distance travelled) give their kinetic energies.

Common features:

In the tutorial we have concentrated mainly on the features that tell us about the decays of strange particles (link to ptleprop1). Since these are weak-interaction decays (like beta-decay), the particles have a long enough lifetime to travel a measurable distance before they decay. Visual analysis of bubble chamber pictures is mainly one of looking for.

Another source of useful information:

It is very satisfying to be able to recognize particles as an exercise in pattern recognition; however, it is not always possible – for example, particles might leave the bubble chamber before decaying.

(It must also be remembered that, in a real experiment, tracks are then measured – on more than one view if we are to be able to reconstruct the event in 3-dimensions - with the aim of determining the energies and momenta of as many particles as possible.)

We end with three exercise events:

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