Application of maximum-likelihood method to decomposition of positron-lifetime spectra to finite number of components

A procedure for application of the maximum-likelihood method to decomposition of positron-lifetime spectra to a finite number of exponential components has been developed. The Poisson-distribution character of the raw data is taken into account explicitly. The model fitted is characterized through the lifetimes and relative intensities of the individual components, the parameters of the time resolution function (a sum of the three gaussians) and a constant background, Parametrization in terms of the two-state trapping model without detrapping is also included. Parameter optimization is performed by means of general minimization system MINUIT. Brief description of the method is presented and experience with its use is discussed.