A modified decaying source method for dead time measurement with non-negligible background counts

This study aims to propose a modified decaying source method for dead time measurement with non-negligible background counts. A radiation portal monitor (RPM) system with 173×28.4×6.4 cm3 sized PVT scintillation detectors was used for the experiment. For each source, various activities were measured to evaluate counting losses due to the dead time, and three types of sources were considered to validate the energy dependency of the dead time. The results showed that the evaluated true count rate based on the nonparalyzable dead time model is in good agreement with the experimental data and the dead time increases when the energy of the incident radiation decreases. The proposed method is expected to be used for dead time measurement of radiation detection systems with non-negligible background counts.