The invention relates to a detector for measuring nuclear radiation, especially gamma-radiation, comprising a scintillator crystal with a light decay time of less than 100 ns, a silicon drift detector (SDD) for the measurement of both direct hits of low energy radiation and the light, being emitted from the scintillator crystal, the silicon drift detector being mounted between the scintillation crystal and the radiation entry window, a preamplifier, connected to the SDD, electronic devices, being capable of determining the signal rise time of the measured signals and of separating the signals on the basis of said rise time, electronic devices, being capable of separately collecting the energy spectra of SDD and scintillator detection events on the basis of the different rise times.