Tau-sterile neutrino mixing in nomad

During several years, the KARMEN experiment was reporting for an anomalous signal which was interpreted as a possible existence of heavy sterile neutrinos. The NOMAD experiment has the capability to search for such an isosinglet neutrino. It is assumed that the (νs) couples to the νt produced in the SPS neutrino beam at CERN. Analysis of NOMAD data leads to a single candidate event, compatible with the background expectations. This allows to set for the first time a limit on the mixing strength between sterile and tau neutrinos, in the mass range 10 to 190 MeV. (author)