Determination of Argon-41 gas concentration in the 13 MeV cyclotron room using Monte Carlo method

Neutrons are generated from collisions of protons with a target in the cyclotron will interact with the air in the cyclotron room. Argon-40 gas contained in air activated to produce Argon-41 that decays by emitting gamma radiation. The resulting gamma radiation increases over of the dose for radiation workers. The Argon-41 concentration depends on the neutron spectrum and geometry of cyclotron equipment. In this study, the concentration of Argon-41 which is formed simulated using Monte Carlo method and a computer program PIHTS. Based on the simulation shown that saturated concentrations of Argon-41 in the 13 MeV cyclotron room is 66 ± 3 Bq/m³ per μA. In brief operation of the cyclotron with a current proton beam of 50 μA, generated 1050 ± 50 Bq/m³ per hour of Argon-41. It is therefore necessary ventilation at a rate of 5.4 m³ per hour to reduce the Argon-41 to concentrations below 200 Bq/m³. (author)