COMPUTER SIMULATION OF POSITRON LIFETIME DISTRIBUTIONS

摘要

Resolution of positron lifetime distributions is commonly done by assuming a distribution to consist of a small number of exponentially decaying components. The mean lifetime and intensity of each component is then determined by a curve-fitting program such as POSITRONFIT. An alternative is to use a Laplace inversion method to obtain a continuous distribution of intensities as a function of mean lifetime, using a program such as CONTIN.[1] However, when there are a large number o.f lifetime components (or a broad peak in the spectrum in a Laplace inversion), one wonders whether the time resolution of a given lifetime apparatus produces a result that is adequate for the extraction of the detailed information that may be implied by the computer fit. Another question concerns the assumption that each orthopositronium (o-Ps) atom is likely to remain in a single hole for its entire lifetime. If it does not, then one can only determine average hole sizes rather than hole-size distributions. A calculation is presented regarding this question.