Matrix approach for processing liquid scintillation spectra of 14C

Abstract

We developed a matrix approach for processing 14C spectra measured in benzene with a Quantulus 1220TM liquid scintillation spectrometer. For this, we consider and analyze the high-energy part of the spectra between 200 and 550 channels, where the role of the quenching effect is low. We process-bind the spectra around the 14C endpoint and then shift the sample spectrum ±25 channels relative to the calibration to find the optimum where the spectral shapes match the most. For optimization, we use the squared difference between the sample spectrum and the reconstructed spectrum based on calibration. The developed set of software code works in the Matlab or Octave environment. This set of codes allows accurate 14C calculation (pMC and age) for spectra over a practically acceptable wide quenching range using only a few 1-2 sets of spectra (calibration and background). This confirms while performing cross-validation on many individual samples spectra and particularly when sets of calibration spectra were measured for the same sample under different quenching conditions.