Direct measurement of fixed-charge stopping power for 32-MeVHe1+3in a charge-state nonequilibrium region

The energy loss of 32-MeV ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ ions passing through carbon foils of 2–100 μg/${\mathrm{cm}}^2$ thickness was measured with use of a high-resolution magnetic spectrograph. The measurement was made for ions emerging in the same charge state as the incident beam. Energy-loss spectra of ${}_{}{}^3{}_{}{}^{}\mathrm{He}_{}^{1+}{}_{}{}^{}$ for thinner foils showed a single peak, while for thicker foils two peaks appeared. From energy-loss spectra with a single peak, the fixed-charge stopping power of carbon for ${}_{}{}^3{}_{}{}^{}\mathrm{He}_{}^{1+}{}_{}{}^{}$ at 20.7${\mathit{v}}_0$ a.u. was deduced. The result was compared with other experiments and theoretical predictions.