Single and Double Charge Transfer inC4+-He Collisions

Cross sections for single and double charge transfer from ${\mathrm{C}}^{4+}$ incident on He have been measured and calculated for relative velocities between (0.2 and 1.2) × ${10}^8$ cm/sec. The double-charge-transfer cross section rises with decreasing energy and is predicted to be nearly two orders of magnitude larger than that for single charge transfer at the lowest velocity. The single- and double-charge-transfer cross sections are experimentally found to be equal at a velocity of 6.5 × ${10}^7$ cm/sec with a value of 2.7 × ${10}^{-16\mathrm{}}$ ${\mathrm{cm}}^2$.