Evaluation of Neutron Field Parameters at the VITA Facility Using Geant4 Simulation

Parameters of the neutron field generated at the VITA (Vacuum Insulated Tandem Accelerator) installation are assessed using Monte Carlo simulation in the Geant4 software package. A detailed model of the target section of the installation is developed, including the output accelerator tube, frontal lithium target for neutron generation, backplate cooling system, and neutron moderator system. The simulation makes it possible to obtain the energy and spatial distributions of the neutron flux intensities in the configuration intended for irradiation of small biological objects at a proton energy of 2.05 MeV. It is shown that the obtained calculated values of the neutron flux intensities correspond to the target values, providing acceptable time intervals for irradiating biological objects. Moreover, the transverse profiles of the simulated neutron field are consistent with the experimental data and preliminary theoretical expectations. The developed model can be used for dose planning in experiments on irradiation of small biological objects in vitro and in vivo and for further optimization of the neutron beam formation system to increase a therapeutic index in neutron capture therapy.