A gamma vector camera is described for detecting and determining the energy spectrum of a gamma ray source and the direction to the gamma ray source. The gamma vector camera includes a detection system that records a track of a recoil electron produced by a Compton-scattering of an incident gamma ray emitted by the gamma ray source. A processor is configured to determine the energy and the direction of the recoil electron based on the track of the recoil electron recorded by the detection system, and to determine the energy spectrum of the gamma ray source and the direction to the gamma ray source based on the determined energies and directions of a plurality of recoil electrons produced by the Compton-scatterings of a respective plurality of incident gamma rays.