Abstract
The proton total reaction cross sections of 41 elements have been measured at 99 MeV, using a double Faraday cup to measure the proton-beam attenuation. The results are consistent with the semiclassical form of the absorption cross section with a nuclear radius parameter of 1.47 fm (1 fm = 10−13cm) and a mean free path for 99-MeV protons in nuclear matter of 5.7 fm.