Discrete and continuous analysis of positron lifetime spectra: A comparison

Positron lifetime spectra in poly[1-(trimethylsilyl)]propine membranes were collected at different temperatures and various number of accumulated coun ts, in order to compare the results from analyses obtained by different dec ay models: discrete (that is, purely exponential) or continuous (with at le ast one distribution of lifetimes). Analysis into four discrete components is inadequate, unless a low number of counts (1 to 2 millions) is accumulat ed. Conversely, deconvolutions which allow the ortho-positronium lifetime t o be distributed give satisfactory fits, even at the highest statistics (60 millions). An equivalent good fit in terms of chi(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.