Optimization and validation of charge transport simulation for hybrid pixel detectors incorporating the repulsion effect

TL;DR

This paper introduces two open-source Monte Carlo simulation methods that explicitly incorporate charge repulsion to accurately model charge transport in hybrid pixel detectors, validated against experimental X-ray data.

Contribution

The paper develops and validates two novel Monte Carlo simulation methods with charge repulsion modeling for high-resolution hybrid pixel detectors, enhancing accuracy in charge transport simulation.

Findings

Both methods show excellent agreement with experimental data.

Charge repulsion significantly affects charge carrier distributions.

The simplified spherical model reduces computational complexity.

Abstract

For emerging applications of hybrid pixel detectors which require high spatial resolution, e.g., subpixel interpolation in X-ray imaging and deep learning-based electron localization, accurate modeling of charge transport processes in the sensor is highly demanded. To address this, two open-source, time-stepping Monte Carlo simulation methods have been developed, both explicitly incorporating charge repulsion, which are found necessary for accurate simulation when charge sharing becomes important. The first method employs brute-force calculations accelerated by GPU computing to model charge carrier dynamics, including drift, diffusion, and repulsion. The second utilizes a simplified spherical model that significantly reduces computational complexity. A parameterization scheme of the charge transport behaviors has been developed to enable efficient and rapid generation of X-ray simulation events. Both methods were rigorously validated using experimental data collected with a monochromatic X-ray beam at the METROLOGIE beamline of the SOLEIL synchrotron, demonstrating excellent agreement with measured pixel-energy spectra across various sensor thicknesses, bias voltages, and photon energies. Furthermore, the impact of the repulsion effect on charge carrier distributions was quantitatively evaluated. The potential applications of these simulation methods for different particle detections and detector technologies are also discussed.