Stopping power of Ni, Ag, Au, and Pb for ∼7-MeV/nucleonαparticles and carbon ions:Z13deviation from the Bethe formula

The stopping powers of Ni, Ag, Au, and Pb for ∼7-MeV/N (where $N$ means nucleon) C ions and $\alpha$ particles have been measured. For the 7.00-MeV/N C ion, the stopping powers of Ni, Ag, Au, and Pb are found to be 1.353±0.016, 1.080±0.010, 0.832±0.006, and 0.825±0.006 MeV / mg ${\mathrm{cm}}^2$, respectively. From these results, the $Z_1^3$ deviation from the Bethe-Bloch formula is evaluated comparing with our experimental stopping power for $\alpha$ particles. In the course of analysis we employed appropriate effective-charge corrections. Pierce and Blann's effective-charge correction, e.g., gives a reasonable value (1.38) of the $b$ which appears in the Ritchie-Brandt theory, if a $\chi$ value of 1.29 in their theory is assumed.