Number 171 (Story #4), April 1, 1994 by Phillip F. Schewe and Ben Stein NEUTRINO OSCILLATIONS , the transformation of one neutrino type (electron, muon, or tau) to another, is invoked to explain the solar neutrino problem: a detector designed to monitor electron-type neutrinos from the sun will fail in its job if, on the way to Earth, electron neutrinos are turning into muon neutrinos. A new generation of terrestrial experiments searching for neutrino oscillation are now being planned. All involve accelerator-produced neutrinos and the study of their fluxes at various points along a baseline. One scheme uses neutrinos from CERN in Switzerland and a detector at Gran Sasso in Italy, 732 km away. Another experiment involves shooting neutrinos from Fermilab, near Chicago, up to the Soudan II detector in Minnesota. (Science, 18 Feb.)