A model for positron annihilation in multi-layer systems by solving the diffusion equation using different positron affinities
Abstract
We present a method for solving the positron diffusion equation in multi-layer systems. Our approach incorporates material-specific implantation profiles, diffusion parameters, and positron affinities. It utilizes a Markov chain approach to model annihilation probabilities and provides fitting capabilities for experimental S (lineshape) parameter data. We have implemented this algorithm in Python and made it available for free under the name LIMPID. To demonstrate its performance, we analyze depth-resolved Doppler-Broadening Spectroscopy measurements of a Cu layer on a Si substrate, achieving excellent agreement with the experimental profiles. The LIMPID tool enhances the reproducibility and comparability of positron defect characterization measurements across different research groups.
Cite
@article{arxiv.2511.02889,
title = {A model for positron annihilation in multi-layer systems by solving the diffusion equation using different positron affinities},
author = {Lucian Mathes and Michael Göldl and Michael Leitner and Bettina Kohlhaas and Maximilian Suhr and Vassily Vadimovitch Burwitz and Armin Manhard and Christoph Hugenschmidt},
journal= {arXiv preprint arXiv:2511.02889},
year = {2025}
}