Development of a High-Efficiency 4 $\pi\beta$ (LS)– $\gamma$ Coincidence System for Dire

We developed a new 4πβ (LS)-γ coincidence counting system to be used for radionuclide standardization. The liquid scintillation detector used in this system enables the easy preparation of sources without self-absorption. A special β- β coincidence technique is implemented to suppress large thermal and electronic noises, resulting in a higher coincidence efficiency and reduced uncertainty in the measurements of low-energy beta-emitting radionuclides. The system is commissioned with the activity measurement of ⁶⁰Co. The measured activity is derived with 90% efficiency for the β-ray detection.