Improved method for the calculation of the counting efficiency of electron-capture nuclides in liquid scintillation samples.

The methods to compute the counting efficiency of electron-capture nuclides in liquid scintillation counting have been improved in several previous studies. The main improvements comprise a more realistic treatment of the ejection of photoelectrons and subsequent rearrangement processes in the atomic shell as well as a more detailed atomic rearrangement model. The latter was realized in the MICELLE code by means of a new stochastic approach. This new model was also developed to account for energy deposits within micelles. The recent improvements have now been combined in an updated version of the MICELLE code, which also makes the computation of the counting efficiency of complex decay schemes possible. In this paper, we describe and discuss recent extensions and improvements of the models and further corrections. The calculated counting efficiencies of selected radionuclides are compared with the experimental data obtained by liquid scintillation counting. For the measurements, we use standard solutions, which were calibrated by other methods.