Omega minus produced by 4.2GeV K-

This remarkable event shows the production and decay of an omega-minus by a 4.2 GeV beam particle in the CERN 2 metre hydrogen bubble chamber.

In this event there are two vees: one comes from the primary interaction while the other comes from the kink. (You can check this by printing off the event and then following back - with a ruler - the line joining the point where the vee tracks cross to the vee decay point. It clearly points to the kink.)

The track from the kink must be a or a , depending on whether the parent particle was an or a . This track itself kinks, quite considerably, telling us that it is a . (The mass of a is so close to that of a that it could not provide the energy to produce such a sharp kink.)

So, without any measurements, we have identified an decaying to .

A measurement of the event reveals that the reaction is