Simulation study of energy resolution with changing pixel size for radon monitor based on Topmetal-Ⅱ^- TPC

作     者：Meng-Yao Huang Hua Pei Xiang-Ming Sun Shu-Guang Zou 

作者机构：Department of Physics and Astronomy Iowa State University PLAC Key Laboratory of Quark & Lepton Physics (MOE)Central China Normal University College of Information Science and Engineering Henan University of Technology 

出 版 物：《Nuclear Science and Techniques》 (核技术（英文）)

年 卷 期：2019年第30卷第1期

页      面：49-57页

核心收录：

学科分类：082704[工学-辐射防护及环境保护] 08[工学] 0807[工学-动力工程及工程热物理] 0827[工学-核科学与技术] 0703[理学-化学] 0702[理学-物理学] 0801[工学-力学（可授工学、理学学位）] 

基　　金：supported by the National Natural Science Foundation of China(No.U1732271) 

主　　题：Geant4 Energy resolution Pixel size Radon monitor Topmetal 

摘      要：In this paper, we study how pixel size influences energy resolution for a proposed pixelated detector—a high sensitivity, low cost, and real-time radon monitor based on a Topmetal-Ⅱ^- time projection chamber(TPC). This monitor was designed to improve spatial resolution for detecting radon alpha particles using Topmetal-Ⅱ^- sensors assembled by a 0.35 lm CMOS integrated circuit process.Owing to concerns that small pixel size might have the side effect of worsening energy resolution due to lower signalto-noise ratio, a Geant4-based simulation was used to investigate the dependence of energy resolution on pixel sizes ranging from 60 to 600 lm. A non-monotonic trend in this region shows the combined effect of pixel size and threshold on pixels, analyzed by introducing an empirical expression. Pixel noise contributes 50 keV full-width at half-maximum energy resolution for 400 lm pixel size at 1–4σ threshold that is comparable to the energy resolution caused by energy fluctuations in the TPC ionization process( ~20 keV). The total energy resolution after combining both factors is estimated to be 54 keV for a pixel size of 400 lm at 1–4σ threshold. The analysis presented in this paper would help choosing suitable pixel size for future pixelated detectors.