Simulation and evaluation of γ signal detection from P–¹¹B reactions in EHL-2

The p–¹¹B fusion reaction produces gamma particles (γ) exhibiting fixed energy, in contrast to the broad energy spectrum of the concurrently produced α-particle signals. This sharp spectral signature makes γ a more effective diagnostic than the α energy spectrum. However, the intense x-ray background inherent to magnetic confinement fusion devices complicates the identification of γ signals. This study establishes a comprehensive γ detection and evaluation framework for the p–¹¹B reaction with the Geant4 program, which can acquire the signals received by detectors according to various plasma parameters. By optimizing the detector spatial configuration by simulation, optimal signal acquisition performance can be achieved; meanwhile, the likelihood ratio test method is adopted to evaluate the degree of interference by background x-rays on characteristic signals. The results provide a theoretical basis for optimizing the operational performance of the ENN He-Long 2 (EHL-2) spherical torus, encompassing x-ray background suppression, plasma configuration and optimization of the discharge regime.