Absolute measurement of activity of ¹⁹⁸Au foils using the 4πβ-γ coincidence counting method and corrections by the Monte Carlo simulation.

The thermal neutron fluence rate is determined by the gold activation method. The absolute activity of the irradiated gold foil is measured by a 4πβ-γ coincidence counter. Using this method, corrections for the detection of conversion electrons and gamma rays by a 4πβ counter are very important to obtain accurate absolute activity. In this work, Monte Carlo simulations were performed to derive the correction factor K. The absolute measurement of (198)Au activity for 20-100 μm thickness Au foils were performed to verify the calculating model of the 4πβ-γ coincidence counting system.