  Feshbach resonances are fundamental to interparticle interactions and become
particularly important in cold collisions with atoms, ions, and molecules. Here
we present the detection of Feshbach resonances in a benchmark system for
strongly interacting and highly anisotropic collisions -- molecular hydrogen
ions colliding with noble gas atoms. The collisions are launched by cold
Penning ionization exclusively populating Feshbach resonances that span both
short- and long-range parts of the interaction potential. We resolved all final
molecular channels in a tomographic manner using ion-electron coincidence
detection. We demonstrate the non-statistical nature of the final state
distribution. By performing quantum scattering calculations on ab initio
potential energy surfaces, we show that the isolation of the Feshbach resonance
pathways reveals their distinctive fingerprints in the collision outcome.
