Chapter 11: The Superjets Affair

In 1995 a group of physicists from Pisa and Frascati led by Paolo Giromini finally completed a measurement which had kept them busy for several years: the determination of the total cross section of 1.8 TeV proton–antiproton collisions, a number which is a fundamental input to any determination of the luminosity of a data sample. In the early 1980s, the Italians had built a set of detectors specifically designed to track small-angle particles emitted in the very forward direction. Those detectors, called “roman pots,” provide an accurate measurement of the rate of interactions that do not break up the protons. A detailed study of the resulting data allowed a threefold decrease in the systematic uncertainties on the total cross section. This translated directly into a reduction from 15 to 5% of the uncertainty in the integrated luminosity of all CDF datasets. It was an important contribution to the scientific output of the experiment, as the precision of the cross section of all rare phenomena measured by the experiment improved by the same factor…