Validation of Geant4's G4NRF module against nuclear resonance fluorescence data from $^{238}$U and $^{27}$Al

TL;DR

This study validates the Geant4 G4NRF module against experimental nuclear resonance fluorescence data for uranium-238 and aluminum-27, demonstrating reasonable agreement within 20% and establishing its accuracy for NRF simulations.

Contribution

The paper provides the first comprehensive validation of the G4NRF module against experimental NRF data for specific isotopes, quantifying its accuracy and reliability.

Findings

Agreement within 15-20% for $^{238}$U NRF transitions

Agreement within 8% for $^{27}$Al NRF transitions

Relative NRF rate ratios agree within 4% and are statistically zero

Abstract

G4NRF is a simulation module for modeling nuclear resonance fluorescence (NRF) interactions in the Geant4 framework. In this work, we validate G4NRF against both absolute and relative measurements of three NRF interactions near 2.2 MeV in $^{238}$U and $^{27}$Al using the transmission NRF data from the experiments described in arXiv:1712.02904. Agreement between the absolute NRF count rates observed in the data and predicted by extensive Geant4+G4NRF modeling validate the combined Geant4+G4NRF to within $15$--$20\%$ in the $^{238}$U NRF transitions and $8\%$ in $^{27}$Al, for an average $13\%$ discrepancy across the entire study. The difference between simulation and experiment in relative NRF rates, as expressed as ratios of count rates in various NRF lines, is found at the level of ${\lesssim}4\%$, and is statistically identical to zero. Inverting the analysis, approximate values of the absolute level widths and branching ratios for $^{238}$U and $^{27}$Al are also obtained.