A single-moderator neutron spectrometer for neutron spectrum studies in BNCT

The Single-moderator Neutron Beam Spectrometer (SNBS) based on SiC detector and cylindrical moderator was designed, in which the front surface of SiC detector was covered with LiF coating. A model of the device was established using FLUKA and the response matrix of 100 energy points was calculated. These energy points were uniformly selected in the logarithmic coordinate range of 2 × 10^-9 MeV-20 MeV. At the Radiation Metrology Station of the China Institute of Radiation Protection, a²⁵²Cf neutron source was used for calibration, and the detection efficiency correction coefficients corresponding to each detector were obtained. Subsequently, SNBS was tested at the BSA beam outlet on the CPHS accelerator platform at Tsinghua University. Based on the results, the overall deviation between the measured results and the theoretical calculated values under different measurement conditions was calculated, the maximum measurement relative deviation is less than 10 %. Finally, the proportion of thermal neutrons, epithermal neutrons, and fast neutrons was analyzed. The overall measurement results are basically consistent with the calculated results. SNBS is compact and suitable for measuring high-throughput neutron radiation fields in narrow spaces.