The world's first neutrino observation in a hydrogen bubble chamber.
It was found Nov. 13, 1970, in this photograph from the Zero Gradient Synchrotron's
12-foot bubble chamber. The invisible neutrino strikes a proton where three
particle tracks originate (lower right). The neutrino turns into a mu-meson,
the long center track (extending up and left). The short track is the proton.
The third track (extending down and left) is a pi-meson created by the
Argonne National Laboratory