分类： 物理学 >> 核物理学 提交时间： 2024-03-11
摘要： Fast neutron flux measurements with high count rates and high time resolution have important applications in equipment such as tokamaks. In this study, real-time neutron and gamma discrimination was implemented on a self-developed 500-Msps, 12-bit digitizer, and the neutron and gamma spectra were calculated directly on an FPGA . A fast neutron flux measurement system with BC-501A and EJ-309 liquid scintillator detectors was developed and a fast neutron measurement experiment was successfully performed on the HL-2M tokamak at the Southwestern Institute of Physics, China. The experimental results demonstrated that the system obtained the neutron and gamma spectra with a time accuracy of 1ms. At count rates of up to 1 Mcps, the figure of merit was greater than 1.05 for energies between 50 keV and 2.8 MeV.
分类： 物理学 >> 核物理学 提交时间： 2024-01-03
摘要： Online -spectrometry systems for inland waters, most of which extract samples in situ and in real time, are able to produce reliable activity concentration measurements for waterborne radionuclides only when they are distributed relatively uniformly and enter into a steady-state (SS) diffusion regime in the measurement chamber. To protect residents health and ensure the safety of the living environment, better timeliness is required for this measurement method. To address this issue, this study established a mathematical model of the online water -spectrometry system so that rapid warning and activity estimates can be obtained for water under non-steady-state (NSS) conditions. In addition, the detection efficiency of the detector for radionuclides during the NSS diffusion process was determined by applying the computational fluid dynamics (CFD) technique in conjunction with Monte Carlo simulations. On this basis, a method was developed that allowed the online water -spectrometry system to provide rapid warning and activity concentration estimates for radionuclides in water. Subsequent analysis of the NSS-mode measurements of 40K radioactive solutions with different activity concentrations determined the optimum warning threshold and measurement time for producing accurate activity concentration estimates for radionuclides. The experimental results show that the proposed NSS measurement method is able to give warning and yield accurate activity concentration estimates for radionuclides 55.42 and 69.42 min after the entry of a 10 Bq/L 40K radioactive solution into the measurement chamber, respectively. These times are much shorter than the 90 min required by the conventional measurement method. Furthermore, the NSS measurement method allows the measurement system to give rapid (within approximately 15 min) warning when the activity concentrations of some radionuclides reach their respective limits stipulated in the Guidelines for Drinking-water Quality of the WHO, suggesting that this method considerably enhances the warning capacity of in situ online water -spectrometry systems.
分类： 物理学 >> 核物理学 提交时间： 2023-10-15
摘要： In -ray imaging, localization of the -ray interaction in the scintillator is critical. Convolutional neural network (CNN) techniques are highly promising for improving -ray localization. Our study evaluated the generalization capabilities of a CNN localization model with respect to the -ray energy and thickness of the crystal. The model maintained a high positional linearity (PL) and spatial resolution (SR) for ray energies between 591460 keV. The PL at the incident surface of the detector was 0.99, and the resolution of the central incident point source ranged between 0.521.19 mm. In modified uniform redundant array (MURA) imaging systems using a thick crystal, the CNN -ray localization model significantly improved the useful field-of-view (UFOV) from 60.32% to 93.44% compared to the classical centroid localization methods. Additionally, the signal-to-noise ratio (SNR) of the reconstructed images increased from 0.95 to 5.63.
分类： 管理学 >> 管理学其他学科 提交时间： 2022-11-24 合作期刊: 《2022年第三届传播、创新和经济管理国际研讨会》
摘要： China has large population, with the development of social and economic, the number of medical waste is growing rapidly. The medical waste is highly infectious and hazardous, that requires us to pay more attention to its proper treatment. China's legal mechanism for medical waste started late, the existing main laws and regulations is Law of the People's Republic of China on the Prevention and Control of Environmental Pollution by Solid Waste and Regulations on the Administration of Medical Wastes. These have made some achievements in the management of medical waste in China and brought the medical waste industry into the track of legal management. But we have to admit that environmental pollution, social security and other problems caused by medical waste occur frequently, and the treatment of medical waste is particularly important. In order to effectively promote the improvement of this problem, in line with the requirements of the 19th National Congress of the CPC on ecological protection, it is necessary to start from the construction of the legal system, drawing on foreign experience in the legal system of medical waste, combining with the actual situation in China, establishing an effective legal system, so as to achieve effective prevent environmental pollution and promote the sustainable development of society.
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