Search for short-lived particles in high-energy neutrino interactions identified using a hybrid emulsion—spark-chamber arrangement

Seventeen litres of nuclear photographic emulsion have been exposed to the wide-band neutrino beam at Fermilab. Tracks of secondaries from neutrino interactions in the emulsion were observed in a wide-gap spark chamber and a system of narrow-gap spark chambers and counters down beam. From measurements on the tracks in the wide-gap chamber the positions of vertices from which the secondaries diverged were predicted and 37 neutrino interactions in emulsion were located. Factors affecting the efficiency of location of events searched for (approx.20% in this experiment) are assessed and conclusions drawn about means of optimizing the design of experiments employing emulsion hybrid techniques. In one of the interactions a secondary track gave rise to three tracks after a distance of 182 ..mu..m. Further measurements made on this event do not alter the previous conclusion of its most likely interpretation as the decay of a short-lived particle of lifetime approx.6 x 10/sup -13/ sec.