共查询到20条相似文献,搜索用时 140 毫秒
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为了得到X射线条纹相机中CsI光阴极的高能电子份额数据,通过蒙特卡罗方法建立模型来研究CsI光阴极在X射线照射下的光电发射特性.研究了CsI光阴极厚度为100~1 000 nm、入射X射线能量为1~30 keV时的二次电子(SE)能量分布.模拟结果显示,入射X射线的能量越高、CsI光阴极的厚度越大,从CsI光阴极出射的二次电子中高能电子(大于50 eV)的份额越高,在入射X射线能量为30 keV、CsI光阴极厚度为1 000 nm时,出射电子中的高能电子份额可以达到10.8%.但是当CsI光阴极厚度保持为100 nm、而入射X射线能量大于15 keV时,高能电子份额维持在3.4%左右而不再随入射X射线的能量增加而增加. 相似文献
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为了稳定而有效地探测能量范围在0.110keV之间的软X射线,研制并优化了一种高低密度夹心结构的透射式CsI光阴极。它的光子探测效串大约是高密度透射式CsI光阴极的110倍。所测得的光电发射次级电子能量分布曲线与高密度CsI光阴极类似,半极限值的全宽度(FWHM)不到2eV。由于它的量子效率高而次级电子能量分布范围相当窄,这种夹心结构透射式CsI光阴极广泛地应用于软X射线探测器和计数器,特别是软X射线条纹摄相管。 相似文献
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本文对双区共腔半导体双稳态激光器在从吸收区背面及沿轴向外部光注入下的稳态及瞬态特性进行了计算机模拟,得到稳态光开关及光放大特性,瞬态情况下随着注入光的增强输出由近混沌状脉动到单峰快衰减张弛振荡而更强光注入时则仅存在一延迟过程. 相似文献
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利用整体毛细管X光半会聚透镜会聚同步辐射 总被引:1,自引:1,他引:0
为了进一步开展基于整体毛细管X光半会聚透镜和同步辐射的微区X射线分析,利用整体毛细管X光半会聚透镜和超环面镜的组合会聚了同步辐射。在8 keV能量点,利用超环面镜,将面积为2.3 mm×26 mm,竖直发散度和水平发散度分别近似为0和1.1 mrad的同步辐射光束会聚为面积为0.9 mm×0.3 mm,水平和竖直发散度分别为1.4 mrad和0.1 mrad的束斑,然后利用整体毛细管X光半会聚透镜将束斑会聚成直径为21.4μm的微焦斑,该整体毛细管X光半会聚透镜对束斑的传输效率为7.9%,该透镜焦距和焦斑处单位面积上的强度(功率密度)增益分别为13.3 mm和59。 相似文献
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《中国无线电电子学文摘》2004,(2)
TN91 2004020672荃于电吸收锡筛叨器的解复用器窗口特性分析及优化/王安斌,伍剑,林金桐(北京邮电大学)11光学学报一2 003,23(10)一1210一1214数值模拟了基于电吸收调制器EAM解复用器的开关窗口特性,在考虑邻道串扰和强度抖动(由同步偏离和时间抖动导致)的光时分复用数值模型中对解复用信号的误码率进行分析.数值模拟结果表明,电吸收调制器的窗口特性(消光比和窗口宽度)满足4 x 10Gb/S的光时分复用通信系统中解复用器的要求;在小的偏置电压下,邻道串扰和解复用器的透过率特性必须仔细考虑以达到最小的误码率;在大的偏置电压下,较大的射频… 相似文献
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GaAs粒子探测器的能谱特性 总被引:1,自引:1,他引:0
阐述了具有 M- S- M结构的 Ga As粒子探测器在α、β粒子、光子、X射线辐照下 ,在室温时测得的能谱特性。对2 41 Am 5.48Me V的α粒子 ,其电荷收集率 (CCE)和能量分辨率 (FWHM)的最好结果分别为 45%和 7%。对 5 7Co 1 2 2 ke V的 X射线能量分辨率约为 30 %。该探测器对 90 Sr2 .2 7Me V的β粒子有最小的电离粒子谱。探测器在累积照射量为 1 3 k Gy的光子 1 3 7Cs(662 ke V)辐照下 ,辐照前后的电荷收集率无明显变化。诸多实验结果表明 ,该探测器具有较强的抗辐射能力 相似文献
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电子材料分析中的能谱干扰峰 总被引:2,自引:0,他引:2
主要阐述了在电子元器件分析中用能谱仪作定性分析时常见的一些干扰峰和容易混淆及误判的一些谱峰。主要有和峰、逃逸峰以及一些在元器件材料分析中常遇到的元素特征峰之间的交错重叠的识别和判定方法,并把这些容易误判的谱线整理列成3种表格,以供参考,这些数据基本覆盖了在X射线能谱仪中可能出现的所有相关的谱峰。 相似文献
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Harness the Power of Upconversion Nanoparticles for Spectral Computed Tomography Diagnosis of Osteosarcoma
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Yingying Jin Dalong Ni Lu Gao Xianfu Meng Yi Lv Fang Han Hua Zhang Yanyan Liu Zhenwei Yao Xiaoyuan Feng Wenbo Bu Jiawen Zhang 《Advanced functional materials》2018,28(33)
Osteosarcoma, as the most common primary bone cancer, is difficult to make a differentiation between tumor with contrast agents (CAs) accumulation and healthy bones using X‐ray computed tomography (CT) since they both display high attenuation of X‐ray. Recently, an advanced CT form, gemstone spectral CT (GSCT), has received extensive attention due to its significant ability of material decomposition and monochromatic images, which can overcome the above disadvantages of conventional CT. Herein, the lutecium (Lu)‐based upconversion nanoparticles (UCNPs, polyethylene glycol (PEG)–NaLuF4:Yb/Er), which possess great spectral CT performance over clinical used iohexol, is investigated as a novel kind of spectral CT CAs in the diagnosis of osteosarcoma. Both in vitro and in vivo experiments show that Lu‐based UCNPs provided much more diagnostic interpretation, and can successfully distinguish the osteosarcoma from the surround bones with GSCT while the iohexol fails due to the different X‐ray attenuation characteristics of UCNPs (i.e., lutecium) and iohexol (e.g., iodine) under different energy. As a proof of concept, the Lu‐based UCNPs with excellent biocompatibility hold great potential for further clinical diagnosis of skeletal system diseases. 相似文献
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Fundamental operation of the first buried-channel charge-coupled device (BCCD) in 6H-SiC is presented. The n-type buried-channel was formed by ion implantation of nitrogen, and a double level overlapping-polysilicon-gate process was adapted to the SiC MOS system. An electron mobility of 200 cm2/Vs was measured in the channel, which is doped 1.6×1017 cm-3. An eight-stage, four-phase BCCD shift register was operated in the pseudo-two-phase configuration at room temperature. At 5.5 kHz, the charge transfer efficiency is greater than 99.4% 相似文献
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《Electron Devices, IEEE Transactions on》1984,31(7):904-909
A new configuration of CCD imager has been developed to improve smearing. This new sensor introduces a storage region, which consists of pairs of vertical BCCD registers, between an interline transfer CCD imaging region and a readout horizontal CCD register. The configuration and operation of the new device (FIT-CCD imaging device) are described, together with the experimental results for 402(H) times 500 (V) element imaging devices. The smear level observed is low as ∼0.45 percent at 50 times the saturation exposure, being the lowest level so far obtained in solid-state imagers. Degradation in the contrast transfer function due to introduction of the storage region is very little because of the minimized vertical transfer loss by the storage region configuration with pairs of half-long BCCD registers. 相似文献
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This paper optimizes the buried channel charge-coupled device (BCCD) structure fabricated by complementary metal oxide semiconductor (CMOS) technology. The optimized BCCD has advantages of low noise, high integration and high image quality. The charge transfer process shows that interface traps, weak fringing fields and potential well between adjacent gates all cause the decrease of charge transfer efficiency (CTE). CTE and well capacity are simulated with different operating voltages and gap sizes. CTE can achieve 99.999% and the well capacity reaches up to 25 000 electrons for the gap size of 130 nm and the maximum operating voltage of 3 V. 相似文献
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针对28 GHz车联网中车对基础设施(Vehicle-to-Infrastructure,V2I)毫米波信道,开展了准平稳区间的研究.首先,分析了信道准平稳区间的理论基础和计算方法.其次,利用功率相关(Correlation of Power,CP)算法和谱散度(Spectral Divergence,SD)算法进行准平稳区间的计算.结果表明,CP算法复杂度低且精度较高,更适合用于计算V2I通信场景下的准平稳区间.最后,利用CP算法计算出的准平稳区间作为新的采样间隔,从而减少了射线跟踪仿真器的采样点数.通过原始采样和减少采样点后的信道特性的比较,在合理的门限值下,利用信道准平稳区间的方法加速了射线跟踪仿真器,并且不会造成信道参数的失真.另外,对于信道特性的分析结果也对车联网在毫米波频段的仿真和设计具有重要意义. 相似文献