Kassiopeia: A Modern, Extensible C++ Particle Tracking Package

TL;DR

Kassiopeia is a flexible, efficient, and extensible C++ software package designed for complex particle tracking in experiments with intricate geometries and electromagnetic fields, supporting advanced physics simulations.

Contribution

It introduces a novel algorithmic paradigm for particle tracking that emphasizes customizability, extensibility, and ease of use for complex physics simulations in experimental settings.

Findings

Supports simulation of complex differential equations of motion

Incorporates stochastic processes like scattering and decay

Offers a rich geometry framework for diverse physics applications

Abstract

The Kassiopeia particle tracking framework is an object-oriented software package using modern C++ techniques, written originally to meet the needs of the KATRIN collaboration. Kassiopeia features a new algorithmic paradigm for particle tracking simulations which targets experiments containing complex geometries and electromagnetic fields, with high priority put on calculation efficiency, customizability, extensibility, and ease of use for novice programmers. To solve Kassiopeia's target physics problem the software is capable of simulating particle trajectories governed by arbitrarily complex differential equations of motion, continuous physics processes that may in part be modeled as terms perturbing that equation of motion, stochastic processes that occur in flight such as bulk scattering and decay, and stochastic surface processes occuring at interfaces, including transmission and reflection effects. This entire set of computations takes place against the backdrop of a rich geometry package which serves a variety of roles, including initialization of electromagnetic field simulations and the support of state-dependent algorithm-swapping and behavioral changes as a particle's state evolves. Thanks to the very general approach taken by Kassiopeia it can be used by other experiments facing similar challenges when calculating particle trajectories in electromagnetic fields. It is publicly available at https://github.com/KATRIN-Experiment/Kassiopeia