his dues and more, and from then on he would concentrate on the physics he liked best.

Beginning in the summers of the 1950s Rod Cool would spend occasional evenings at moderate-stake poker games with visiting physicists. Sometimes the games were continued at hotel rooms during physics conferences in the United States and abroad. With his wartime training of poker played with fellow officers in the Signal Corps, Rod held his own and more. More important, the poker led to long-time collaborations with fellow players John Tinlot of Rochester and Leon Lederman then at Columbia.

With Tinlot, Lederman, and others, Cool played a major role in measurements of muon proton scattering at high momentum transfers. Then—and to a lesser extent now—the question "Is the muon just a heavier electron?" was unanswered. The most important result of the experiment was that at rather high momentum transfers and correspondingly small distances the muon did just act as a heavy electron. Although then and now the difference in mass was not understood. Also, the electron-proton scattering measurements that probed the electromagnetic structure of the proton and were used by Friedman, Kendall, and Taylor to demonstrate that nucleons had "hard" constituents (i.e., quarks), albeit invaluable, were marred to some extent by the necessity of large corrections for the radiation of the electrons upon collision. While the fluxes of muons were much inferior to the electron currents available, the muons radiated less by a factor of about 40,000 enabling analyses that were superior in some ways.

After going to Rockefeller, Cool assembled an excellent group of younger physicists and with these colleagues Rod moved his efforts again to the world's highest energy accelerator newly built at Fermilab, 30 miles west of Chicago, which accelerated protons to 400 GeV. His work there