GEANT4 simulation study of over-response phenomenon of fiber x-ray sensor
Bin Zhang(张彬)1, Tian-Ci Xie(谢天赐)1, Zhuang Qin(秦壮)2, Hao-Peng Li(李昊鹏)1, Song Li(李松) 1, Wen-Hui Zhao(赵文辉)1, Zi-Yin Chen(陈子印)3, Jun Xu(徐军)4, Elfed Lewis5, and Wei-Min Sun(孙伟民)1,†
1 Key Laboratory of In-fiber Integrated Optics, Ministry of Education, Harbin Engineering University, Harbin 150001, China; 2 Electronic Engineering College, Ministry of Education, Heilongjiang University, Harbin 150001, China; 3 Comprehensive Cancer Center, First Affiliated Hospital of Harbin Medical University, Harbin 150001, China; 4 Comprehensive Cancer Center, Second Affiliated Hospital of Harbin Medical University, Harbin 150001, China; 5 Optical Fiber Sensors Research Centre, University of Limerick, Castletroy, Limerick, Ireland
Abstract The purpose of this article is to explore the cause of the over-response phenomenon of fiber x-ray sensor. The sensor is based on a length of PMMA fiber, whose end is filled with the scintillation material Gd2O2S:Tb. The Monte Carlo simulation software GEANT4 uses the phase space file provided by the International Atomic Energy Agency (IAEA), by irradiating the fiber x-ray sensor in the water phantom, counting the fluorescence signal of the optical fiber x-ray sensor after propagation through the fiber. In addition, the number of Cerenkov photons propagating through the fiber is also counted. Comparing this article with previous research, we believe that one of the reasons for the over-response of the fiber x-ray sensor is the non-linear response of the deposition energy of the scintillator to the fluorescence. By establishing a region of interest and counting the x-rays in this region, the simulation results show that the counted number of x-rays that may affect the fiber x-ray sensor is the biggest in the area of interest at a water depth of 5 cm. This result is close to the maximum dose point of the experimental and simulated percentage depth dose (PDD) curve of fiber x-ray sensor. Therefore, the second reason of the over-response phenomenon is believed to be fact that the inorganic materials such as Gd2O2S:Tb have larger effective atomic numbers, so the fiber x-ray sensors will cause more collisions with x-ray in a low energy region of 0.1 MeV-1.5 MeV.
Fund: Project supported by the Natural Science Foundation of Heilongjiang Province, China (Grant No. ZD2019H003), the Joint Research Fund in Astronomy under Cooperative Agreement Between the National Natural Science Foundation of China and Chinese Academy of Sciences (Grant Nos. U1631239 and U1931206), the 111 Project, China (Grant No. B13015), and the Fundamental Research Funds for the Central Universities to the Harbin Engineering University, China.
Bin Zhang(张彬), Tian-Ci Xie(谢天赐), Zhuang Qin(秦壮), Hao-Peng Li(李昊鹏), Song Li(李松), Wen-Hui Zhao(赵文辉), Zi-Yin Chen(陈子印), Jun Xu(徐军), Elfed Lewis, and Wei-Min Sun(孙伟民) GEANT4 simulation study of over-response phenomenon of fiber x-ray sensor 2021 Chin. Phys. B 30 048701
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