Discrete and Continuous Analysis of Positron Lifetime Spectra: a Comparison

Abstract

Positron lifetime spectra in poly [1-(trimethylsilyl)]propine membranes were collected at different temperatures and various number of accumulated counts, in order to compare the results from analyses obtained by different decay models: discrete (that is, purely exponential) or continuous (with at least one distribution of lifetimes). Analysis into four discrete components is inadequate, unless a low number of counts (1 to 2 millions) is accumulated. Conversely, deconvolutions which allow the ortho-positronium lifetime to be distributed give satisfactory fits, even at the highest statistics (60 millions). An equivalent good fit in terms of x 2 test is obtained with a five discrete components analysis, from which it is possible to extract information on the first moments (centroid and standard deviation) of ortho-positronium lifetime distribution.