By measuring the range deficit of 955-MeV/u ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ ions in copper, the authors have identified very large deviations of the stopping power from the standard Bethe-Bloch formula. They show that this discrepancy can be accounted for by higher-order terms in the Mott cross section and by the relativistic Bloch correction. The significance of this result with regard to two high-energy astrophysics experiments is discussed.

• Received 3 November 1982

DOI:https://doi.org/10.1103/PhysRevLett.50.1110