The observation of prompt neutrinos from 400 GeV proton nucleus interactions

Events due to neutral primaries have been observed in BEBC during an experiment in which 3.5 10/sup 17/ protons of 400 GeV from the CERN- SPS were dumped into a large copper target. These events have the general characteristics of neutrino interactions; however not all the 70 events of energy greater than 10 GeV can be attributed to conventional sources ( pi , K or hyperon decay); in particular the observation of 11 events with an emerging e/sup -/ and 4 e/sup +/ events requires a new, prompt source of neutrinos. The intensity of this source is estimated and possible origins such as charmed particle or heavy lepton decay are considered; an upper limit is also placed on the production of axions. (8 refs).