The Back-scattering Problem in Three Dimensions

In this thesis we study the (inverse) back-scattering problem for the Schr"odinger operator in $R^3$. We introduce the back-scattering transform $B(v)$ of a real-valued potential $vin C_0^infty(R^3)$, and prove that the back-scattering data associated to $v$ determine $B(v)$. Under the assumption that the Schr"odinger operator $H_v=-Delta +v$ has no eigenvectors in $L^2(R^3)$ it is shown that $B(v)$ may be expressed in terms of the wave group $K_v(t)=sin(tsqrt{H_v})/sqrt{H_v}$. We prove also that the mapping $vmapsto B(v)$ is a homeomorphism in a neighbourhood of the origin in the Banach space $X_0^r$, which is the completion of $C_0^infty(R^3;R)$ w.r.t. the norm $fmapstosum_{|a|=1}|d^af|_{L^1}$.