The Research on the Suppression of Spurious Neutrons for a Neutron Detector Array that May Be Used in the Neutron Scattering

摘要

In the neutron scattering, the angular distribution of neutrons scattered by the tested sample is measured to calculate the momentum transfer in the scattering process, to understand the microstructure information of the tested material. Because of the existence of structural materials in the neutron detector array, spurious neutrons may undergo collisions with atoms in the structural materials before they are measured by the detector array. Thus, a background is introduced to the angular distribution of neutrons scattered by the tested sample, leading to a deteriorated interpretation of the microstructure of the tested material. The RT/S, which reflects a ratio between the noncollided neutrons and spurious neutrons, is researched for various boron-lined gaseous detectors. A newly-designed boronlined honeycomb converter based gaseous neutron detector is introduced in this paper to provide a higher RT/S, benefitting from its anisotropy of neutron sensitivity. Based on the simulation (GEANT4 and Garfield) and preliminary experimental results, a 3 to 10 time improvement for the RT/S can be realized with this newly-designed neutron detector. The suppression of spurious neutrons can significantly improve the analyzing quality of microstructure information for the tested material.