The caption next to the wall shown above, from the exhibition Of Large and Small at the Royal Library in Copenhagen, says:
"The pictures were taken in a 2 metre long bubble chamber in CERN in Switzerland in 1967. They were used for studying so-called strong interactions at proton clashes with the - at that time - very highest energy level. At this time one began to understand that protons themselves were built from smaller parts, and on pictures it is possible to see a number of particles created by the clashes."
I think it is safe to say that these are among the most interesting traces ever left on film since the birth of photography (btw, today is Daguerre's birthday).
See for yourself:
And if you want some more, you only have to ask.