Angular distribution of binary encounter electrons

The double differential cross section, DDCS, of the binary encounter electrons (BEe) in 1 MeV/u Fq+ + H2 (q = 4, 6, 8, 9) is measured from 0 to 70 degrees with respect to the beam direction. At 0 degrees the data confirm the decrease of the cross section with increasing projectile charge state. At larger observation angles, the data are in fair agreement with the prediction proposed by Shingal et al. where the ratio of the DDCS for 6+ ions to bare ions is less than 1 for θlab > 30 degrees and greater than 1 for θlab < 30 degrees as recently observed for Cq+. We also observed that the energies of the BEe peak are charge state, q, independent at 0 degrees observation angle, but q dependent at larger observation angles