Designing of diagnostic system for neutron penumbral imaging based on Shenguang-Ⅲ facility

The aperture for neutron penumbral imaging is newly designed in order to reduce the difficulties of fabrication and detecting. Firstly, the source-detector and source-aperture distances are fixed on because of the neutron yield of Shenguang-Ⅲ facility. Then, base on the sharpness and isoplanaticity of the point spread function, the radii of the aperture are optimized. Finally, the resolution of the system is analysed, and the distortions induced by the aperture-fabrication error and misalignment are estimated by the simulation. According to the results, a resolution of 15 m can be satisfied, the fabrication error should be limited to a maximum of 0.1, the precision of alignment should be better than 60 m, the aperture rotation should be within 0.35 mrad, and the source-aperture distance error should be less than 1 mm.