In this paper we want to discuss the quantum mechanical measuring process within the realm of many body quantum theory. Our starting point is to consider this process as a special scattering phenomenon where within one of the partners, i.e. the many body measuring device, a collective coherent motion is induced by the interaction with the microobject. We start our investigation with the many body system having a large but finite number N of degrees of freedom which is the real situation. We then study in detail what will happen in the limit N → ∞, however emphasizing that this transition is actually only performed in the mind of the observer. This implies that certain tail events together with their phase correlations have to be truncated. We show that the dichotomy "pure state" versus "mixture" as outgoing scattering states will vanish in this limit in so far as it has no observable consequences provided one is only interested in the state of the microobject. Furthermore, we discuss the role of the observer, the notion of "event", the relation between single preparation and ensemble picture, and the so-called "reduction of the wave function" in the light of our approach, i.e. explaining the phenomena accompanying the measuring process in terms of many body quantum theory.