Suppression of 40K-Induced background in gamma-ray spectrometry for food radioactivity analysis: A Monte Carlo study

Improving the sensitivity of gamma-ray spectrometry is crucial for food safety monitoring. However, naturally abundant 40 K in these foods generates significant continuous spectrum background that severely interferes with the detection of other key environmental radionuclides. This study conducted Monte Carlo simulations in Geant4 to systematically quantify the interference mechanism of 40 K in gamma-ray energy spectrum measurements. Simulations indicate that the continuous spectrum of bremsstrahlung radiation emitted by 40 K beta particles is the primary source of interference, leading to a significant increase in the background level. The optimized sample container structure proposed in this study reduces the 40 K background in the target energy region (e.g., the 210 Pb region) by approximately 57%, improving the detection sensitivity with a 17% reduction in the relative minimum detectable activity.