First neutrino event in a hydrogen bubble chamber

First neutrino event in a hydrogen bubble chamber was found on Friday the 13th of November on film taken with the Argonne 12-foot chamber. A neutrino coming from the left interacted with a proton to produce the three-pronged event consisting of μ⁻ (longest track), a proton (shortest track) and a π⁺. Neutrino-proton interactions had previously been observed in a propane chamber at CERN, but not in a hydrogen chamber. Both Argonne and Brookhaven, which has a 7-foot chamber, are preparing to start long runs to measure neutrino-nucleon interactions. Neither device is completely shaken down yet, though. Argonne will have neutrino beams of 0.5-1.5 GeV/c, and Brookhaven will have one that peaks at 2-3 GeV/c. The Argonne chamber will continue to run with hydrogen during an initial exposure of about 500 000 pictures. Based on the success of this running, the chamber will then be scheduled for a deuterium filling and an additional one million pictures. This later run will study the axial vector form factor in the weak interaction, as will the Brookhaven run, which will start with 300 000 pictures in deuterium; 700 000 pictures more are proposed for a later run.

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