Electron emissions are studied for the double-electron capture with simultaneous single ionization process in 30 keV/u He${}^{2+}$-Ar atom collision using the reaction microscope technique. Double-differential cross sections have been obtained for emission angles of 0°, 20°, 45°, 90°, 128°, and 175° and electron energies ranging from 0 to 80 eV. No cusp-shaped electrons centered at a speed equal to that of the incident projectile in the forward direction are observed, which is contrary to the earlier results [D. Fregenal, J. Fiol, G. Bernardi, S. Suarez, P. Focke, A. D. Gonzalez, A. Muthig, T. Jalowy, K. O. Groeneveld, and H. Luna, Phys. Rev. A 62, 012703 (2000)]. An explanation has been provided to clarify the observed results in the current reaction channel.

• Received 3 November 2013
• Revised 16 January 2014

DOI:https://doi.org/10.1103/PhysRevA.89.032708