Coincidence studies of electron impact ionization of atomic inner shells

We consider (e,2e) processes on the 2s and 2p shells of argon and magnesium. We present triple differential cross sections in coplanar asymmetric geometry calculated in the Plane Wave Born, 1st Born and Distorted Wave Born approximations. We show that the currently available relative experiments can not easily distinguish between these approximations. We make proposals for relative experiments where the difference between these approaches can be more readily observed.