An algorithm for intrinsic gain and offset stabilization of gamma-ray pulse height spectra

A new algorithm for the intrinsic stabilization of the pulse height spectra (PHSs) of multiply scattered γ-rays that makes gain and offset corrections based on spectral shape is described. In the implementation, the input spectrum is transformed from assumed values of gain and offset to a set of standard values. The PHSs are projected onto four spectral principal components, and the mean square error between the transformed input spectrum and its rank four representation is minimized. For noise-free spectra, it was found that the algorithm can estimate gain with a root mean square (RMS) error of 1%, and offset with an RMS error of 0.6 keV when the spectral components were determined from the test data. For noisy spectra the RMS errors for gain and offset were 4% and 1.7 keV, respectively