Attenuation correction for C-14 quantification by bremsstrahlung measurement with a germanium detector

Abstract Bremsstrahlung, generated when beta rays from carbon-14 interact with materials, offers a non-invasive method for radioactivity measurement in plants. However, because low-energy bremsstrahlung is attenuated by absorbers, attenuation correction is required. This study proposed an attenuation correction method that estimates absorber thickness by analyzing the count ratio in low- and high-energy regions of the spectra. Simulations and experiments were conducted using a germanium detector and soda-lime glass plates as absorbers. Experimental data revealed low-energy background components not observed in simulations, which were successfully estimated and subtracted using a Gaussian approximation. After background subtraction, experimental results aligned well with simulation data, demonstrating a linear relationship between the count ratio and absorber thickness. After applying the attenuation correction, the radioactivity became nearly constant for all glass thicknesses. This approach provides a foundation for non-invasive carbon-14 quantification and has potential applications in radiotracer studies on photosynthetic products in plants.