In 1983, the European Muon Collaboration published results from an experiment conducted at CERN in which the DIS reaction was measured for high-energy muon scattering from iron and deuterium targets. It was expected that the cross section for DIS from iron divided by that from deuterium, and scaled by a factor of 28 (the iron-56 nucleus has 28 times more nucleons than deuterium) would be approximately 1. Instead, the data (Fig. 1) showed a decreasing slope in the region of 0.3 < x < 0.7, reaching a minimum of 0.85 at the largest values of x .