A method and device are provided for obtaining the energy of nuclear radiation from a scintillation detector system for the measurement of nuclear radiation the device comprising a scintillation crystal, a light readout detector and a fast digital sampling analog to digital converter. The method comprises obtaining the anode current at the LRD for at least one scintillation event with N photo electron charges at the entrance of the LRD, sampling the measured anode current, obtaining the function of the scintillation pulse charges Qdint(N, G) at the anode of the LRD from said scintillation events, obtaining the RMS of the noise power charge Qdrms(N, G), obtaining the function QdSN(N) by calculating the ratio of Qdint(N, G) and Qdrms(N, G), obtaining the constant gradient k from the function QdSN(N)=Qdint(N, G)/Qdrms(N, G)=k*N, and obtaining N.
