Cold Target Recoil Ion Momentum Spectroscopy: a ‘momentum microscope’ to view atomic collision dynamics

Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS) is a novel momentum space imaging technique for the investigation of the dynamics of ionizing ion, electron or photon impact reactions with atoms or molecules. It allows the measurement of the previously undetectable small three dimensional momentum vector of the recoiling target ion created in those reactions with high resolution and 4π solid angle. Combined with novel 4π electron momentum analysers it is a momentum microscope for kinematically complete scattering experiments. We review the technical development, outline the kinematics of atomic reactions from the perspective of the recoil ion, and give an overview of the studies performed with this technique. These studies yield kinematically complete pictures of the correlated motion of the fragments of atomic and molecular breakup processes, unprecedented in resolution, detail and completeness. The multiple-dimensional momentum-space images often directly unveil the physical mechanism underlying the many-particle transitions investigated. The experiments reviewed here include reactions of single and multiple capture and ionization induced by keV proton to GeV/u U92+ impact, electron and antiproton impact ionization as well as single and double ionization by photoabsorbtion and Compton scattering from threshold to 100 keV. We give an outlook on the exciting future prospects of the method for atomic physics and other fields of science.