Prompt neutrino production in the 1982 beam dump experiment at CERN

Principles of beam dump experiments are reviewed and the 1982 beam dump at CERN using the Big European Bubble Chamber is described in detail. Neutrino events have been detected using both the bubble chamber and its associated electronic detectors. Prompt event rates are established for Vμ , Ṽμ , Ve and Ṽe . The prompt rates are consistent with lepton universality. The charm production cross-section required to explain the prompt electron-(anti)neutrino signal is approximately 16-105/μb per nucleon, assuming linear dependence of this cross-section on nucleon number. This range of values reflects the fact that we have not been able to find a model which is consistent with all aspects of the data. The neutral to charged current ratio for electron-neutrinos is found to be 0.23 ±0.16. The expected number of tau-neutrino events is estimated and kinematic and visual searches for tau-neutrino interactions are described. One visually detected candidate is described in detail. No positive evidence for a tau-neutrino interaction has been found. From the ratio of neutral to charged current events in the data we infer that no more than 4% of the prompt charged current events and 40% of the total prompt signal may be attributed to tau-neutrinos at 90% CL.