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RISS 인기검색어
- 검색키워드
- 저자 : Guo Siming (검색결과 4 건)
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Siming Guo,Jinjie Wu,Zhongjian Ma,Guanjia Li,Qingbin Wang 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.4
Gas detectors based on a 3He proportional counter play an important role in monitoring the ambient dose equivalent in nuclear reactors and particle accelerators, and the time resolution of such gas detectors is directly related to the accuracy of dose equivalent values when gas detectors are used in pulsed neutron fields. In this article, the dead-time of a proportional 3He counter is measured experimentally, and two methods to correct for the omitted counts resulting from the dead-time effect are adopted. The moderation time of neutrons passing through the moderator of a neutron detector is calculated by means of Monte Carlo simulation software; thus, the equation between the neutron counting rate and the correction coecient in accelerator radiation fields is deduced. In the other method, the parameters of the correction equation are derived experimentally in the pulsed radiation fields around accelerators, and the correction equation is determined. The dead-time effects of neutron detectors due to pulsed radiation can be corrected effectively by using the two methods introduced in this paper.
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Determination of the air-kerma in mammography x-rays at NIM
Ji Wang,Siming Guo,Pingzhou Lu,Jinjie Wu,Ying Liu,Ruonan Li,Yulong Wang 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.4
Breast cancer has become the top killer of women’s health in the world, and mammography X-ray has become the gold standard in various diagnostic methods, due to its low energy, low dose and high resolution. To meet the quality control requirements of mammography X-rays dose in clinical, the National Institute of Metrology (NIM,China) has established a mammography X-ray reference radiation facility. The radiation quality half-value layer (HVL) range from 0.274 to 0.364 mm (aluminum) meets the requirements of IEC61267, and a new parallel-plate free-air ionization is designed. At NIM, various correction factors were measured and simulated, and fnally, the absolute measurement of the X-ray air kerma rate of the mammography was realized. By analysis, the combined standard uncertainty of the air kerma is 0.44%. Provide traceability services for the use and quality control of mammography in China.
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Research on the temperature characteristics of SiPM-based LaBr3(Ce) detectors
Yu Tao,Guo Siming,Wu Jinjie,An Zhenghua,Qie Xiaoyu,Guo Kaiyue 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.1
When a satellite-borne detector is being ground calibrated, a standard detector is required to determine the monochromatic X-ray beam energy and intensity. For this purpose, a SiPM-based LaBr3(Ce) detector has been developed. The environmental temperature change may substantially afect the performance of the detector, thus afecting the accuracy of the ground calibration results. To study the efect of temperature change on the performance of the LaBr3(Ce) detector, the performance of the LaBr3(Ce) detector was tested with 241Am and 137Cs γ-ray sources in the high- and low-temperature test chambers. The results showed that within the range of – 20 to 40 °C, the energy resolution of the LaBr3(Ce) detector does not change by more than 1%, nor does the peak-to-total ratio of 241Am and 137Cs. The temperature change has little efect on the performance of the LaBr3(Ce) detector, which meets the requirements for use as a beam monitor. However, the peak location of the radioactive source varies signifcantly with temperature, and the diference with the peak location at room temperature is within 17%. To reduce the variation in the gain of the LaBr3(Ce) detector with temperature, it is necessary to optimize the compensation design of the temperature gain to ensure the stability of the detector gain at various temperatures.
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Optimization of a double crystal monochromator
Jiang Zheng,Wang Eryan,Song Ruiqiang,Guo Siming,Wu Jinjie,Hou Dongjie,An Zhenghua,Zhou Pengyue 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.8
The double crystal diffraction structure based on Bragg diffraction is the core component of the monochromator that is widely used in synchrotron radiation beam lines and monochromatic X-ray radiation devices. The stability of monochromatic X-rays produced by using the T-structure double crystal monochromator at National Institute of Metrology was investigated experimentally. Due to its structural defects, the X-ray flux of the T-structured double crystal monochromator shows poor long-term stability. Inspired by the Channel-cut monochromator structure, we designed a new double crystal monochromator structure to improve the long-term stability of the X-ray flux. Experiments showed that the stability of the monochromatic X-ray flux for the new double crystal monochromator structure was better than 1.0%@1 h, and the energy region and flux rate of the monochromatic X-rays are significantly improved. This work provides a stable and reliable monochromatic X-ray source for the calibration of X/γ detectors such as satellite load detectors, which will contribute to the development of X/γ detection technology.
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