The influence of the unknown de-excitation pattern in the analysis of ββ-decay total absorption spectra

The method of analysis of ββ-decay total absorption spectra in order to obtain ββ-strength distributions is studied. The influence on the final result of unknown branching ratios in the electromagnetic de-excitation of levels in the daughter nucleus is investigated with the help of the statistical model of the population and decay of the nucleus. The total decay strength appears to be rather insensitive to assumptions on the branching ratios and the systematic uncertainty on the shape of the strength distribution is quantified.