Analytical method used in some branches of chemistry and physics for the measurement of the intensities and energies of gamma radiation. Scintillation or semi-conductor radiation detectors, coupled to various types of electronic circuitry, enable a spectrum to be accumulated. This may be used to identify the gamma-emitting radioisotopes, and their energy intensities can be used to determine concentrations of the corresponding elements. The technique is also used in remote sensing to determine the abundance of some elements in distant objects, e.g. the surface of the Moon.