Effects and optimizations of image charge technology on the imaging performance of capacitive division image readout MCP detectors

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Vol. 1069; p. 169879
• Main Authors: Wang, Bo, Yang, Kai, Bai, Yonglin, Cao, Weiwei, Bai, Xiaohong, Zheng, Jinkun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2024
• Subjects: Capacitive charge division; Finite element method; Image charge; Image nonlinearity; Finite element method; Image charge; Image nonlinearity; Capacitive charge division
• ISSN: 0168-9002
• DOI: 10.1016/j.nima.2024.169879

A finite element model is proposed to investigate the impact of image charge technology on the imaging performance of capacitive division image readout (C-DIR) devices. Through detailed simulation analysis, we explore the charge density of the induction layer and each electrode layer in the multilayer capacitive anode. The position nonlinearity is calculated for various resistances per square of the induction layer and substrate thicknesses. The simulation results indicate a strong linear correlation between the position nonlinearity and substrate thickness, and an exponential decay relationship with the logarithmic resistance per square of the induction layer. The C-DIR detector is experimentally tested for imaging nonlinearity and counting rate, with the resistance per square of the induction layer ranging from 0.005 to 1000 MΩ, and the substrate thickness ranging from 1 to 5 mm. The experimental results validate the simulation conclusions and reveal the impact of the “charge accumulation effect” and “shielding effect” on the imaging performance of the detector, as well as the “imaging compression” phenomenon. Optimized image charge readout technology enables the C-DIR detector to achieve an imaging nonlinearity of 1.53% in the experiment.