Combining Particle Tracking with Electromagnetic Radiation Showers: Merging GPT and Geant4 with Visualization

TL;DR

This paper presents a novel integration of GPT and Geant4 to simulate electron trajectories and losses in high-field electron injectors, aiding in the design and analysis of accelerator components.

Contribution

It introduces a combined GPT-Geant4 simulation system for detailed electron tracking and visualization in injector beamlines, addressing a gap in current design practices.

Findings

Simulation results agree with literature albedos

Dark current simulation for LCLS-II injector demonstrated

Open-source visualization enhances analysis capabilities

Abstract

Field emitted electrons can seriously affect the operation of high-field, high-duty factor electron accelerators. Accelerated field emission can result in high average power beams which can radiation damage beamline components. In addition, localized losses generate thermal hot spots whose outgassing degrades the ultra-high vacuum required in photoinjectors and cryomodules. However, despite their importance, the effects of field emission are rarely included in the design and engineering of electron injectors. This work attempts to remedy this situation by combining two well-known and well-documented programs, GPT and Geant4, to track electrons and their losses in an injector beamline. This paper describes a system of programs which simulates electron paths and losses along the beamline. In addition, the tracking results can be zoomed and panned along and about the beampipe envelope using an open-source 3D CAD program. The scattering albedo calculations of the combined program, GPT-Geant4, are shown to be in good agreement with the literature albedos. The paper concludes with a dark current simulation for the LCLS-II injector from the cathode to the collimator at 1.5 m from the cathode.