Double ionization of He by antiproton impact using a convergent frozen-correlation approximation

We present a convergent frozen-correlation approximation (CFCA) to evaluate multiple ionization cross sections in ion-atom collisions. We have applied it to the study of double ionization of He by impact of high energy antipr otons and electrons. Comparison with experiment proves that, while the CFCA is almost as simple as an independent electron model, its accuracy is clos e to that of fully correlated treatments.