Study On 14 MeV Neutron Moderators In BNCT

Tumor is a serious threat to human life and health.With the advancement of science and technology,tumor treatment has achieved rapid progress.In recent years,a targeted radiotherapy for cancer cells,Boron Neutron Capture Therapy（BNCT）,has brought great benefits to patients.The high-yield D-T neutron generator has the advantages of small size,high output,movable,shut-off,easy installation and maintenance,has become the best neutron source for BNCT.In order to make the neutrons generated by the D-T neutron generator meet the needs of BNCT,this paper takes MCNP as the main research tool,designs a series of material moderation combinations,and finally finds out a scheme suitable for D-T neutron source moderation.The simulation results show that the single-layer,double-layer and three-layer materials with the best moderating effect are deuterated polyethylene,lead+deuterated polyethylene and tungsten+lead+deuterated polyethylene respectively,and their thermalization efficiency is 3.91×10^-5cm^-2,7.75×10^-5cm^-2,8.78×10^-5cm^-2.The thermalization efficiency of the three-layer material composed of tungsten,lead and deuterated polyethylene is 124.5%higher than that of the single-layer material.Compared with the double-layer material,it is increased by 13.3%.Because of the high price of tungsten and its difficulty in processing,three-layer14MeV neutron moderator materials composed of lead,bismuth and deuterated polyethylene can be used in practical applications.When the thicknesses of lead,bismuth and deuterated polyethylene are 18 cm,9 cm and 21 cm in turn,the maximum thermalization efficiency is 8.15×10^-5cm^-2,the thermal neutron flux of the D-T neutron generator with a yield of 1.4×10¹³n/s in the tumor area can reach 1.14×10⁹n/cm²·s,which is higher than 10⁹n/cm²·s,can be used for BNCT.