Number 93 (Story #1), September 9, 1992 by Phillip F. Schewe and Ben Stein AND NOW, A COSMIC-RAY NEUTRINO PROBLEM . When cosmic rays collide with air molecules in the upper atmosphere, they create neutrinos. Experiments at Japan's Kamiokande neutrino detector and a similar setup in a salt mine near Cleveland, however, have found that the proportion of muon neutrinos to electron neutrinos produced from cosmic rays is significantly smaller than the Standard Model predicts. One possibility is that physicists have miscalculated the amount of muon neutrinos that should be produced in the upper atmosphere. Other explanations, however, involve new physics. One possibility is that the muon neutrinos transform into another type of neutrino on their way to Earth. Such neutrino oscillations have been offered as an explanation for the apparent shortfall of electron neutrinos from the Sun. Indeed, electron and muon neutrinos may be in some kind of equilibrium, according to Thomas Gaisser of the University of Delaware. (Science, 22 August 1992.)