Allpix$^2$: A Modular Simulation Framework for Silicon Detectors

TL;DR

Allpix$^2$ is an open-source, modular simulation framework designed for detailed modeling of silicon pixel detectors, integrating realistic physics processes and electric field maps for improved accuracy.

Contribution

It introduces a flexible, extensible simulation system that combines various physics modules and imported electric field maps for realistic silicon detector modeling.

Findings

Simulation results agree well with test beam data.

Framework enables detailed, first-principles detector simulations.

Modular design facilitates customization and extension.

Abstract

Allpix$^2$ (read: Allpix Squared) is a generic, open-source software framework for the simulation of silicon pixel detectors. Its goal is to ease the implementation of detailed simulations for both single detectors and more complex setups such as beam telescopes from incident radiation to the digitised detector response. Predefined detector types can be automatically constructed from simple model files describing the detector parameters. The simulation chain is arranged with the help of intuitive configuration files and an extensible system of modules, which implement separate simulation steps such as realistic charge carrier deposition with the Geant4 toolkit or propagation of charge carriers in silicon using a drift-diffusion model. Detailed electric field maps imported from TCAD simulations can be used to precisely model the drift behaviour of charge carriers within the silicon, bringing a new level of realism to Monte Carlo based simulations of particle detectors. This paper provides an overview of the framework and a selection of different simulation modules, and presents a comparison of simulation results with test beam data recorded with hybrid pixel detectors. Emphasis is placed on the performance of the framework itself, using a first-principles simulation of the detectors without addressing secondary ASIC-specific effects.