GUIMesh: a tool to import STEP geometries into Geant4 via GDML

TL;DR

GUIMesh is an open-source tool that converts complex STEP CAD geometries into GDML format for Geant4, improving accuracy and detail in space radiation simulations.

Contribution

It introduces GUIMesh, a novel open-source tool that facilitates importing detailed STEP CAD geometries into Geant4 via GDML, addressing limitations of existing solutions.

Findings

Successfully validated geometry conversion accuracy.

Enabled detailed complex geometry import into Geant4.

Provided user-controlled mesh and material options.

Abstract

Detailed radiation analysis of instruments flown in space is critical to ensure mission safety, often requiring the use of state-of-the-art particle transport simulation tools. Geant4 is one of the most powerful toolkits to simulate the interaction and the passage of particles through matter. This framework however, is not prepared to receive Standard for The Exchange of Product data (STEP) files, the most versatile Computer-Aided Design (CAD) format, as inputs requiring previous conversion to other formats. This, especially when the instruments have complex shapes, and/or a large number of volumes may lead to loss of detail and under or overestimation of the quantities under study. Though several solutions have been proposed to import complex geometries into Geant4, so far, only commercial options are available. In this paper we present a new tool, GUIMesh, that embeds FreeCAD libraries, an open-source CAD editor, to tessellate volumes, and convert them to Geometry Description Markup Language (GDML), a Geant4 readable format, in a straightforward way. Several degrees of freedom are given to the user regarding the mesh and choice of material. Different geometries were tested for p material definition, geometry and navigation errors, successfully validating the method used.