Utilization of Si(Li) detector response function and pile-up model in the analysis of x-ray spectra

Qualitative and quantitative analyses of multi-element samples with energy dispersive x-ray fluorescence systems are based on the principle that the individual elemental constituents of the samples excited with a radiation source emit x rays of characteristic energy with intensities that are a function of the corresponding elemental amounts. Results are obtained by analyses of the pulse height spectra obtained as the system response. The mathematical methods used for such an analysis are largely determined by the complexity of the spectra and the particular objectives of the analyst. The method and the difficulties encountered in the analysis of pulse-height spectra are outlined. A model for pulse pile-up distortion of an arbitrary pulse height spectrum and subsequent correction of the spectrum is developed and tested, with both simulated and real spectra. A Si(Li) detector response function for the appropriate x-ray energy range is developed. The response function is used to generate x-ray library standard spectra for direct subsequent use in a linear least-squares program for determining component intensities. Thus, the model allows one to significantly reduce the storage space requirements for experimental library standards