On the ~(252)Cf primary and secondary gamma rays and epithermal neutron flux for BNCT

摘要

Monte Carlo simulation has been used to calculate the different components of neutrons and secondary gamma rays originated by ~(252)Cf fission and also the primary gamma rays emitted directly by the ~(252)Cf source at the exit face of a compact system designed for the BNCT. The system consists of a ~(252)Cf source and a moderator/reflector/filter assembly. To study the material properties and configuration possibilities, the MCNP code has been used. The moderator/reflector/filter arrangement is optimised to moderate neutrons to epithermal energy and, as far as possible, to get rid of fast and thermal neutrons and photons from the therapeutic beam. To reduce the total gamma contamination and to have a sufficiently high epithermal neutron flux we have used different photon filters of different thickness. Our analysis showed that the use of an appropriate filter leads to a gamma ray flux reduction without affecting the epithermal neutron beam quality at the exit face of the system.