Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2019, Vol. 30 ›› Issue (1): 16 doi: 10.1007/s41365-018-0532-8


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

Meng-Yao Huang1 • Hua Pei2 • Xiang-Ming Sun2 • Shu-Guang Zou3   

  1. 1 Department of Physics and Astronomy, Iowa State University, Ames, IA 50010, USA
    2 PLAC, Key Laboratory of Quark & Lepton Physics (MOE), Central China Normal University, Wuhan 430079, China
    3 College of Information Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
  • Received:2018-06-18 Revised:2018-08-28 Accepted:2018-09-09
  • Contact: Meng-Yao Huang Xiang-Ming Sun,
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (No. U1732271).
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Meng-Yao Huang, Hua Pei, Xiang-Ming Sun, Shu-Guang Zou. Simulation study of energy resolution with changing pixel size for radon monitor based on Topmetal-II TPC.Nuclear Science and Techniques, 2019, 30(1): 16     doi: 10.1007/s41365-018-0532-8

Abstract: 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.

Key words: Geant4, Energy resolution, Pixel size, Radon monitor, Topmetal