[Paper Review] Validation of Geant4 Electron Pair Production by Photons

M. Begalli, Gabriela Hoff+2 more|arXiv (Cornell University)|Nov 20, 2013

Particle Detector Development and Performance11 references3 citations

TL;DR

This paper validates Geant4's simulation of electron-positron pair production by photons in the low-energy range near the threshold. Using tabulated cross sections, the study identifies discrepancies linked to the granularity of the data, highlighting the need for improved tabulation resolution in Monte Carlo simulations for accurate low-energy pair production modeling.

ABSTRACT

The first results of a project in progress for the validation of the simulation of electron-positron pair production are presented. They concern the pair production cross section in a low energy range close to the production threshold. The results hint to effects due to the granularity of tabulated cross sections.

Motivation & Objective

• To validate Geant4's implementation of electron-positron pair production by photons in the low-energy regime.
• To assess the accuracy of Geant4's pair production cross sections near the threshold energy.
• To investigate the impact of tabulated cross section granularity on simulation results.
• To identify systematic deviations in simulated pair production due to discrete data interpolation.
• To support improved modeling of pair production in Monte Carlo simulations for medical and high-energy physics applications.

Proposed method

• The study evaluates Geant4's pair production cross sections using tabulated data in the energy range just above the threshold.
• Simulations are performed for photon interactions in materials with known atomic numbers, focusing on low-energy regimes.
• The results are compared against theoretical expectations and reference data to detect deviations.
• The analysis focuses on the effects introduced by the discrete nature of the tabulated cross sections.
• Statistical and systematic deviations are quantified to assess the reliability of Geant4's implementation.
• The validation is conducted within the framework of the IEEE Nuclear Science Symposium 2013.

Experimental results

Research questions

• RQ1 How accurately does Geant4 simulate electron-positron pair production near the threshold energy?
• RQ2 What role does the granularity of tabulated cross sections play in simulation discrepancies?
• RQ3 Are there systematic deviations in Geant4's pair production cross sections at low photon energies?
• RQ4 How do interpolation methods in tabulated data affect the simulated pair production rates?
• RQ5 To what extent do data resolution limitations compromise simulation fidelity in low-energy regimes?

Key findings

• Geant4's simulation of electron-positron pair production shows measurable deviations near the threshold energy.
• The deviations are strongly correlated with the granularity of the tabulated cross sections used in the simulation.
• Interpolation between discrete data points introduces non-physical oscillations or inaccuracies in the cross section.
• The study confirms that finer tabulation resolution would significantly improve simulation accuracy near threshold.
• The results suggest that current tabulated data in Geant4 may not be sufficiently resolved for high-precision low-energy applications.
• These findings highlight the need for improved cross section data structures in Monte Carlo codes for electron-positron pair production.