Activation Radionuclides in the Process of Irradiation of a Niobium Target at the Cyclone 18/9 HC Cyclotrone

Abstract

The accumulation of long-lived radionuclides (LRNs) produced in water [18O]H2O under irradiation at the Cyclone 18/9 HC cyclotron with a niobium target and an input window made of Havar alloy are studied. The most probable nuclear reactions of production and the main nuclear-physics characteristics of LRNs are considered. It is shown that the activity of the majority of LRNs is determined mainly by the dose accumulated by the target. The predominant source of LRNs is an input window made of Havar alloy. The niobium target is the source of the only radionuclide, 92mNb, with negligibly low activity. In the process of water activation, the 7Be and, probably, 65Zn isotopes are produced. The water [18O]H2O, irradiated at the cyclotron, is a dispersed system. Up to 30% of the activity of cobalt and manganese, as well as ~7% of that of chrome, are in the composition of solid particles with sizes of >5 μm washed out from the input foil of the cyclotron target or produced in the redox processes at high-temperature radiolysis of [18O]H2O water.