NOT FINDING THE 17-KEV NEUTRINO

We review the results from magnetic spectrometer searches for heavy ne utrinos with emphasis on recent work at Caltech, Princeton and Tokyo. None of these experiments reveals evidence for a heavy neutrino, admix ed to the usual light neutrino, in the mass range of about 10 to 25 ke V. New measurements with the Caltech iron-free double-focusing magneti c spectrometer rule out, at the the 6sigma level, a 17 keV neutrino ad mixed at 0.85%, and give an upper limit (90% CL) of 0.2% for such an a dmixture.