Development of the mini-ionization chamber for high-dose real-time monitoring inside a gamma irradiation facility

A cylindrical ionization chamber of 0.9 cm³ has been developed for high-doses real-time monitoring during the sample irradiation at a static position in a ⁶⁰Co gamma industrial plant, with about 25.9 PBq (700 kCi). Nitrogen gas at pressure of 1 bar was utilized to fill the ionization chamber for which an appropriate configuration was determined, to be used as a detector for high-dose measurements. The first detector tests were carried out using a ⁶⁰Co Gammacell with about 0.26 PBq (7 kCi) and dose rates of 0.6, 1.8, and 2.6 kGy/h. These dose rates were reached with lead absorbers. A good linearity of the detector was found between dose and accumulated charge, independently of the different dose rates. The developed ionization chamber was suitable to be used as a real-time dosimeter for dose rates between 0.6 to 2.6 kGy/h at a ⁶⁰Co gammacell, independently of the spectrum degradation caused by absorbers between 50%-90%.