Relative Stopping Power of Various Metals for 20-Mev Protons

The stopping powers of Ni, Cu, Cb, Pd, Ag, Cd, In, Ta, Pt, Au, and Th, relative to Al were measured using the 20.6-Mev external proton beam of the University of California at Los Angeles cyclotron. The measurements were made with sufficient precision so that a graph of $\ln Z$ vs stopping power/electron relative to Al showed some fluctuations from a linear relationship. For Th the value differs by 2.6% in the direction found by Kelly and by Teasdale. The results are compared with the data compiled by Lindhard and Scharff.