Discrete and Continuous Analysis of Positron Lifetime Spectra: a Comparison

G. Consolati and F. Quasso Dipartimento di Fisica and Istituto Nazionale per la Fisica della Materia, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy

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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 χ2 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.

DOI: 10.12693/APhysPolA.95.505 PACS numbers: 36.10.Dr, 71.60.+z, 78.70.Bj