Gamma-rays camera is mainly used in image diagnostics of intense pulse radiation sources. The spatial resolution of the camera was measured on a 60Co gamma-rays source with edge method. The spatial resolution MTF (modulation transfer function) at the 10% intensity was about 2 lp/mm and the maximal single-noise ratio (SNR) of the camera was found to be about 5:1. In addition, the spatial resolution of the camera was measured with pulse X-rays with 0.3 MeV in average energy and exclusion of effects of secondary electrons from consideration. Accordingly, the spatial resolution MTF at the 10% intensity was about 5lp/mm, verifying effects of secondary electrons induced by 1.25MeV gamma-rays in the scintillator upon the spatial resolution. Based on our analysis, dispersion sizes of secondary electrons in the scintillator are about 0.4 mm∼0.6 mm. Comparatively, as indicated by detailed analysis of spatial resolutions of the MCP image intensifier and CCD devices, both have little effect on the camera's spatial resolution and could be well neglected.
Hongwei Xie, Jinchuan Chen, Qiang Yi, Faqiang Zhang, Linbo Li, "Evaluation of Major Factors Affecting Spatial Resolution of Gamma-Rays Camera" in Proc. IS&T Int’l. Symp. on Electronic Imaging: Image Quality and System Performance XIV, 2017, pp 147 - 151, https://doi.org/10.2352/ISSN.2470-1173.2017.12.IQSP-232