Direct measurement of fixed-charge stopping power for 32-MeV 3He1+ in a charge-state nonequilibrium region.

The energy loss of 32-MeV $^{3}\mathrm{He}$ ions passing through carbon foils of 2\char21{}100 \ensuremath{\mu}g/${\mathrm{cm}}^{2}$ 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.