Xi- production by high energy neutrino.

production by a high energy neutrino.

This picture was taken in the Big European Bubble Chamber BEBC, filled with hydrogen and exposed to a high energy antinu beam.

The knock-on electron in the top left of the picture tells us that negative particles turn to the right.

The neutrino interaction, which has no incoming beam track because the neutrino is neutral, has 5 final state charged tracks – 3 positive and 2 negative. One of the negative tracks kinks and the vee downstream of the kink, when measured, can be shown be a lambda0 coming from the kink. The outgoing track from the kink was identified as a pion by measurement. This identifies the kinking track as a .

The slower negative track identifies itself as a by making about 1.5 big turns before decaying into three pions.

The remaining positive tracks (h+) cannot be identified but, because more pions are created than any other particle, they are probably pions.
Measurements show that momentum is not conserved transverse to the beam, indicating that at least one neutral particle was produced which left the bubble chamber. (Question: why is it not possible to check momentum conservation in the direction of the beam? Answer: because a neutrino beam has a wide spread of energies, the energy of an individual neutrino is not known.)

The reaction is