Fig. 4
Energy spectra. Investigation of energy spectra. a Comparison of measured (black) and simulated (red) energy spectra for a sample with activity ratio R a = 2.1. The simulated spectrum contains contributions from both isomers and a background template derived from measurement. Energy windows are marked as dotted vertical lines. b Measured energy spectrum for 197(m)Hg. The center and width of the selected photo-peaks is determined from Gaussian fits and used to derive an energy calibration and determine the energy resolution. c Energy calibration (blue) and resolution (green) derived from measurements of each of two 197(m)Hg and 131I photo-peaks. Linear fits were obtained to interpolate for arbitrary energy values