Pure ionization cross section of helium and ionization mechanism

Pure target ionization was investigated for 0.4-6.4 MeV Cq+(q = 1-4) + He and Oq+(q = 1-4) + He collisions. The double-to-single target ionization ratios R21 were measured using coincidence techniques. We compare our results with existing experimental results and find they are in good agreement. The ratio R21 is nearly independent of projectile charge state. The relation of R21 ∼ V is analyzed using the over barrier model (OBM) and ionization probability, which is described in our extended over barrier model. Our calculation agrees well with the experimental results.