Differential die-away technology applied to detect special nuclear materials

Lianjun Zhang,Mengjiao Tang,Chen Zhang,Yulai Zheng,Yong Li,Chao Liu,Qiang Wang,Guobao Wang Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.7

Differential die-away analysis (DDAA) technology is a special nuclear material (SNM) active detection analysis technology. Be a nuclear material shielded or not, the technology can reveal the existence of nuclear materials by inducing fission from an external pulsed neutron source. In this paper, a detection model based on DDAA analysis technology was established by geant4 Monte Carlo simulation software, and the optimal sensitivity of the detection system is achieved by optimizing different configurations. After the geant4 simulation and optimization, a prototype was established, and experimental research was carried out. The result shows that the prototype can detect 200 g of ²³⁵U in a steel cylinder shield that's of 1.5 cm in inner diameter, 10 cm in thickness and 280 kg in weight.

Advanced Gastric Cancer and Perfusion Imaging Using a Multidetector Row Computed Tomography: Correlation with Prognostic Determinants

Huan Zhang,Zilai Pan,Lianjun Du,Chao Yan,Bei Ding,Qi Song,Huawei Ling,Kemin Chen 대한영상의학회 2008 Korean Journal of Radiology Vol.9 No.2

Objective: To investigate the relationship between the perfusion CT features and the clinicopathologically determined prognostic factors in advanced gastric cancer cases. Materials and Methods: A perfusion CT was performed on 31 patients with gastric cancer one week before surgery using a 16-channel multi-detector CT (MDCT) instrument. The data were analyzed with commercially available software to calculate tumor blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability surface (PS). The microvessel density (MVD), was evaluated by immunohistochemical staining of the surgical specimens with anti- CD34. All of the findings were analyzed prospectively and correlated with the clinicopathological findings, which included histological grading, presence of lymph node metastasis, serosal involvement, distant metastasis, tumor, node, metastasis (TNM) staging, and MVD. The statistical analyses used included the Student’s t-test and the Spearman rank correlation were performed in SPSS 11.5. Results: The mean perfusion values and MVD for tumors were as follows: BF (48.14 16.46 ml/100 g/min), BV (6.70 2.95 ml/100 g), MTT (11.75 4.02 s), PS (14.17 5.23 ml/100 g/min) and MVD (41.7 11.53). Moreover, a significant difference in the PS values was found between patients with or without lymphatic involvement (p = 0.038), as well as with different histological grades (p = 0.04) and TNM stagings (p = 0.026). However, BF, BV, MTT, and MVD of gastric cancer revealed no significant relationship with the clinicopathological findings described above (p > 0.05). Conclusion: The perfusion CT values of the permeable surface could serve as a useful prognostic indicator in patients with advanced gastric cancer. Objective: To investigate the relationship between the perfusion CT features and the clinicopathologically determined prognostic factors in advanced gastric cancer cases. Materials and Methods: A perfusion CT was performed on 31 patients with gastric cancer one week before surgery using a 16-channel multi-detector CT (MDCT) instrument. The data were analyzed with commercially available software to calculate tumor blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability surface (PS). The microvessel density (MVD), was evaluated by immunohistochemical staining of the surgical specimens with anti- CD34. All of the findings were analyzed prospectively and correlated with the clinicopathological findings, which included histological grading, presence of lymph node metastasis, serosal involvement, distant metastasis, tumor, node, metastasis (TNM) staging, and MVD. The statistical analyses used included the Student’s t-test and the Spearman rank correlation were performed in SPSS 11.5. Results: The mean perfusion values and MVD for tumors were as follows: BF (48.14 16.46 ml/100 g/min), BV (6.70 2.95 ml/100 g), MTT (11.75 4.02 s), PS (14.17 5.23 ml/100 g/min) and MVD (41.7 11.53). Moreover, a significant difference in the PS values was found between patients with or without lymphatic involvement (p = 0.038), as well as with different histological grades (p = 0.04) and TNM stagings (p = 0.026). However, BF, BV, MTT, and MVD of gastric cancer revealed no significant relationship with the clinicopathological findings described above (p > 0.05). Conclusion: The perfusion CT values of the permeable surface could serve as a useful prognostic indicator in patients with advanced gastric cancer.

Simulation of a neutron imaging detector prototype based on SiPM array readout

Tang Mengjiao,Zhang Lianjun,Tang Bin,He Gaokui,Huang Chang,Zhao Jiangbin,Liu Yang 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.9

Neutron imaging technology as a means of non-destructive detection of materials is complementary to X-ray imaging. Silicon photomultiplier (SiPM), a new type of optical readout device, has overcome some shortcomings of traditional photomultiplier tube (PMT), such as high-power consumption, large volume, high price, uneven gain response, and inability to work in strong magnetic fields. Its application in the field of neutron detection will be an irresistible general trend. In this paper, a thermal neutron imaging detector based on 6 LiF/ZnS scintillation screen and SiPM array readout was developed. The design of the detector geometry was optimized by geant4 Monte Carlo simulation software. The optimized detector was evaluated with a step wedge sample. The results show that the detector prototype with a 48 mm 48 mm sensitive area can achieve about 38% detection efficiency and 0.26 mm position resolution when using a 300 mm thick 6 LiF/ZnS scintillation screen and a 2 mm thick Bk7 optical guide coupled with SiPM array, and has good neutron imaging capability. It provides effective data support for developing high-performance imaging detectors applied to the China Spallation Neutron Source (CSNS).

Efficiency calculation of the ⁿMCP with ¹⁰B doping based on mathematical models

Yang, Jianqing,Zhou, Jianrong,Zhang, Lianjun,Tan, Jinhao,Jiang, Xingfen,Zhou, Jianjin,Zhou, Xiaojuan,Hou, Linjun,Song, Yushou,Sun, XinLi,Zhang, Quanhu,Sun, Zhijia,Chen, Yuanbo Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.7

The ⁿMCP (Neutron sensitive microchannel plate) combined with advanced readout electronics is widely used in energy selective neutron imaging because of its good spatial and timing resolution. Neutron detection efficiency is a crucial parameter for the ⁿMCP. In this paper, a mathematical model based on the oblique cylindrical channel and elliptical pore was established to calculate the neutron absorption probability, the escape probability of charged particles and overall detection efficiency of ⁿMCP and analyze the effects of neutron incident position, pore diameter, wall thickness and bias angle. It was shown that when the doping concentration of the ⁿMCP was 10 mol%, the thickness of ⁿMCP was 0.6 mm, the detection efficiency could reach maximum value, about 24% for thermal neutrons if the pore diameter was 6 ㎛, the wall thickness was 2 ㎛ and the bias angle was 3 or 6°. The calculated results are of great significance for evaluating the detection efficiency of the ⁿMCP. In a subsequent companion paper, the mathematical model would be extended to the case of the spatial resolution and detection efficiency optimization of the coating ⁿMCP.

Stereo Video Transmission Distortion Derived Algorithm Based On Data Partitioning In H.264/AVC

Xiaodong Wang,Jiao Ke,Hanzhang Wang,Lianjun Zhang 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.8

H.264/AVC coding standard slices the encoded Data using the Data Partitioning (DP) based on syntax priority to improve the error resistance for H.264 bit stream. According to this feature, considering the temporal and spatial correlation in stereoscopic video, network performance and terminal error concealment technology. A derived algorithm for determining the transmission distortion based on different DP parts in a Group-of-Pictures (GoP) is proposed. The algorithm takes both the distortion introduced by error diffusion and error concealment into account, which can be estimated by the stereo video quality at encode side under the condition of the specific network. Experimental results show that the algorithm used to calculate the distortion basically coincided with simulation results, and the algorithm can be applied to different sequences with various movement characteristics.

Study on the neutron imaging detector with high spatial resolution at China spallation neutron source

Jiang, Xingfen,Xiu, Qinglei,Zhou, Jianrong,Yang, Jianqing,Tan, Jinhao,Yang, Wenqin,Zhang, Lianjun,Xia, Yuanguang,Zhou, Xiaojuan,Zhou, Jianjin,Zhu, Lin,Teng, Haiyun,Yang, Gui-an,Song, Yushou,Sun, Zhiji Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.6

Gadolinium oxysulfide (GOS) is regarded as a novel scintillator for the realization of ultra-high spatial resolution in neutron imaging. Monte Carlo simulations of GOS scintillator show that the capability of its spatial resolution is towards the micron level. Through the time-of-flight method, the light output of a GOS scintillator was measured to be 217 photons per captured neutron, ~100 times lower than that of a ZnS/LiF:Ag scintillator. A detector prototype has been developed to evaluate the imaging solution with the GOS scintillator by neutron beam tests. The measured spatial resolution is ~36 ㎛ (28 line pairs/mm) at the modulation transfer function (MTF) of 10%, mainly limited by the low experimental collimation ratio of the beamline. The weak light output of the GOS scintillator requires an enormous increase in the neutron flux to reduce the exposure time for practical applications.