Dedicated to the Memory of Dick Slansky

Neutrinos are awesome: of all elementary particles, only neutrinos (not even quarks!) have their own conferences, this year Neutrino-98, on a par with Susy, Strings, Lattices, and the like. It is sobering to remind ourselves that all weak interaction experiments start out wrong, even when performed by the greatest experimentalists of their times. In 1911-1912, using a magnetic spectrometer and photographic plates, O. Von Bayer, O. Hahn, and L. Meitner [1, 2] were the first to measure the spectrum of electrons in β radioactivity. Their conclusion: like α radioactivity, the spectrum of the decay product is discrete! In 1914, Chadwick [3], performed similar measurements in Geiger’s laboratory in Berlin and came out with a different conclusion, that the spectrum of β electrons is continuous. The Great War interrupted the discourse, and the next step in the story were measurements by C. D. Ellis [4] who showed that the discrete lines found earlier were due to internal conversion. Finally in 1927, C.D. Ellis and W. A. Wooster [5] found that the mean energy liberated in β decay accounted for only 1/3 of the allowed energy. By that time even Lise Meitner agreed that the electron spectrum was continuous, setting the stage for W. Pauli’s famous letter. In a December 1930 letter that starts with typical panache, “Dear Radioactive Ladies and Gentlemen...”, W. Pauli proposes a “desperate”way out: there is a companion particle to the β electron. Undetected, it must be electrically neutral, and in order to balance the N − Li statistics, it carries spin 1/2. He