Search for neutral heavy leptons fromν-Nscattering

Results are presented on a search for neutral heavy leptons that couple to muon neutrinos in high-energy neutrino-nucleon interactions ($E_{\nu }$=30–230 GeV). No evidence for such particles is observed. We obtain upper limits on the coupling of neutral neavy leptons to ${\nu }_{\mu }$ below Fermi strength in the mass range 0.25–14 GeV/$c^2$.