Design of a mixed material moderator in a beam-shaping assembly for proton accelerator-based boron neutron capture therapy.

Boron Neutron Capture Therapy is being promoted with the development of accelerator neutron sources, and many new accelerator-based BNCT facilities are being built. In Particle Accelerator Facility project of Sun Yat-sen University, we plan to build a terminal for BNCT research based on an 8 MeV, CW 3 mA proton accelerator. In this paper, we present a beam-shaping assembly for this proton accelerator with such low 24 kW beam power, using composite moderator materials composed of five elements: Mg, Al, F, O, and Li. The calculation result of FLUKA with ENDF/B and JENDL libraries shows that the epithermal neutron beam flux is 1.57 × 10 9 n / cm 2 / s with the CW 3 mA proton beam. The fast neutron component and the gamma ray component under free-air condition are 1.49 × 10 − 13 Gy ∙ cm 2 and 8.12 × 10 − 14 Gy ∙ cm 2 respectively, in line with IAEA-TECDOC-1223 design recommendations. The thermal analysis shows that the maximum temperature of beryllium target is 706.5 K, and the structure materials of BSA do not melt. • The study focused on a neutron source using an 8 MeV, 3 mA linear proton accelerator and a 3-layer target for BNCT. • Based on the neutron target, a combination of moderator materials and a beam-shape assembly were designed. • The neutron beam meets the IAEA requirements with such low proton beam power (24 kW). [ABSTRACT FROM AUTHOR]

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