Bubble chamber picture of decay of sigma+ to a neutron and a pi+

This was produced in a high energy neutrino interaction (hence no visible beam track particles). The neutron goes on to strike a proton which leaves a very small dark track; the decays to a and an positron in a characteristic manner (click here).

For more details of this (rather complicated but) rich event, click here.

For another example of click on the picture below.