The proton beam window （PBW） is one of the key devices of China Spallation Neutron Source （CSNS）. It is the boundary between transport line and target. This paper will present a new PBW structure and detailed ther...The proton beam window （PBW） is one of the key devices of China Spallation Neutron Source （CSNS）. It is the boundary between transport line and target. This paper will present a new PBW structure and detailed thermM-stress analysis. The energy deposition and scattering effect need to be low when the beam passes through the PBW, so proper selection of material and structure is important. According to the study of energy deposition, A5083-O is selected as the PBW material. A single-double layer structure is first proposed based on the study of cooling structures. Thermal analysis and structural optimization are discussed, and transient analysis is done to show the effect of the beam pulse. Besides, safety is confirmed for cases of cooling tunnel blockage, beam profile shrinkage, or centroid orbit offset. All these analyses show the newly designed PBW structure can meet the requirements of the CSNS well.展开更多
The monocrystalline silicon neutron beam window is one of the key components of a neutron spectrom- eter. Monocrystalline silicon is brittle and its strength is generally described by a Weibull distribution due to the...The monocrystalline silicon neutron beam window is one of the key components of a neutron spectrom- eter. Monocrystalline silicon is brittle and its strength is generally described by a Weibull distribution due to the material inhomogeneity. The window is designed not simply according to the mean strength but also according to the survival rate. The total stress of the window is stress-linearized into a combination of membrane stress and bending stress by finite element analysis. The window is a thin circular plate, so bending deformation is the main cause of failure and tensile deformation is secondary and negligible. Based on the Weibull distribution of bending strength of monocrystalline silicon, the optimized neutron beam window is designed to be 1.5 mm thick. Its survival rate is 0.9994 and its transmittance is 0.98447, which meets both physical and mechanical requirements.展开更多
目的 本研究旨在通过影像学资料分析、探讨上颌窦局部解剖结构的差异和相关性及其对侧壁开窗上颌窦底提升主要并发症发生的影响,为避免并发症的发生提供部分参考。方法对380名患者(男性206名,女性174名)的上颌窦影像进行锥形束CT扫描分...目的 本研究旨在通过影像学资料分析、探讨上颌窦局部解剖结构的差异和相关性及其对侧壁开窗上颌窦底提升主要并发症发生的影响,为避免并发症的发生提供部分参考。方法对380名患者(男性206名,女性174名)的上颌窦影像进行锥形束CT扫描分析,分别测量上颌窦宽度、上颌窦外侧壁与内侧壁在上颌窦底形成的角度(lateral and the medial walls with respecttothefloorofthesinus,LFM)、上颌窦外侧壁厚度、上颌窦底黏骨膜厚度、上颌窦外侧壁血管直径、剩余牙槽骨高度,并分析导致侧壁开窗上颌窦底提升并发症发生与局部解剖因素之间的相关性。结果 上颌窦宽度与LFM呈正相关,此相关性在各位点中均具有统计学意义(P<0.05)。剩余牙槽骨高度与上颌窦外侧壁厚度、血管直径与外侧壁厚度、血管直径与剩余牙槽骨高度之间呈正相关,其相关性在部分位点中具有统计学意义(P<0.05)。结论 从影像学角度出发进行研究和统计分析,发现在可能引起侧壁开窗上颌窦底提升并发症的因素中,上颌窦宽度与LFM、剩余牙槽骨高度与上颌窦外侧壁厚度、血管直径与上颌窦外侧壁厚度、血管直径与剩余牙槽骨高度具有正相关关系。展开更多
文摘The proton beam window （PBW） is one of the key devices of China Spallation Neutron Source （CSNS）. It is the boundary between transport line and target. This paper will present a new PBW structure and detailed thermM-stress analysis. The energy deposition and scattering effect need to be low when the beam passes through the PBW, so proper selection of material and structure is important. According to the study of energy deposition, A5083-O is selected as the PBW material. A single-double layer structure is first proposed based on the study of cooling structures. Thermal analysis and structural optimization are discussed, and transient analysis is done to show the effect of the beam pulse. Besides, safety is confirmed for cases of cooling tunnel blockage, beam profile shrinkage, or centroid orbit offset. All these analyses show the newly designed PBW structure can meet the requirements of the CSNS well.
文摘The monocrystalline silicon neutron beam window is one of the key components of a neutron spectrom- eter. Monocrystalline silicon is brittle and its strength is generally described by a Weibull distribution due to the material inhomogeneity. The window is designed not simply according to the mean strength but also according to the survival rate. The total stress of the window is stress-linearized into a combination of membrane stress and bending stress by finite element analysis. The window is a thin circular plate, so bending deformation is the main cause of failure and tensile deformation is secondary and negligible. Based on the Weibull distribution of bending strength of monocrystalline silicon, the optimized neutron beam window is designed to be 1.5 mm thick. Its survival rate is 0.9994 and its transmittance is 0.98447, which meets both physical and mechanical requirements.
文摘目的 本研究旨在通过影像学资料分析、探讨上颌窦局部解剖结构的差异和相关性及其对侧壁开窗上颌窦底提升主要并发症发生的影响,为避免并发症的发生提供部分参考。方法对380名患者(男性206名,女性174名)的上颌窦影像进行锥形束CT扫描分析,分别测量上颌窦宽度、上颌窦外侧壁与内侧壁在上颌窦底形成的角度(lateral and the medial walls with respecttothefloorofthesinus,LFM)、上颌窦外侧壁厚度、上颌窦底黏骨膜厚度、上颌窦外侧壁血管直径、剩余牙槽骨高度,并分析导致侧壁开窗上颌窦底提升并发症发生与局部解剖因素之间的相关性。结果 上颌窦宽度与LFM呈正相关,此相关性在各位点中均具有统计学意义(P<0.05)。剩余牙槽骨高度与上颌窦外侧壁厚度、血管直径与外侧壁厚度、血管直径与剩余牙槽骨高度之间呈正相关,其相关性在部分位点中具有统计学意义(P<0.05)。结论 从影像学角度出发进行研究和统计分析,发现在可能引起侧壁开窗上颌窦底提升并发症的因素中,上颌窦宽度与LFM、剩余牙槽骨高度与上颌窦外侧壁厚度、血管直径与上颌窦外侧壁厚度、血管直径与剩余牙槽骨高度具有正相关关系。
