Novel correction method for X-ray beam energy fluctuation of high energy DR system with a linear detector

A high energy digital radiography (DR) testing system has generated diverse scientific and technological interest in the field of industrial non-destructive testing. However, due to the limitations of manufacturing technology for accelerators, an energy fluctuation of the X-ray beam exists and leads to bright and dark streak artifacts in the DR image. Here we report the utilization of a new software-based method to correct the fluctuation artifacts. The correction method is performed using a high pass filtering operation to extract the high frequency information that reflects the X-ray beam energy fluctuation, and then subtracting it from the original image. Our experimental results show that this method is able to rule out the artifacts effectively and is readily implemented on a practical scanning system.     

太阳能光热化学分解CO_2和H_2O的研究进展

利用太阳能作为能量来源,将CO2和H2O直接转化为化学燃料,既可降低大气中的CO2浓度,又能将太阳能转变为易于储存与运输的化学燃料,对低碳减排以及太阳能利用均具有重要意义.其中太阳能光热化学转化方式可以利用整个太阳能能谱,理论上具有较高的能量转换效率,逐渐受到国际社会的关注.本文简要综述近年来这一研究领域的一些重要进展,总结本课题组在热化学法分解CO2和H2O方面取得的最新结果,对太阳能光热化学转化CO2和H2O的未来发展进行展望.     

Angular reconstruction of a lead scintillating-fiber sandwiched electromagnetic calorimeter

The Neighbor Cell Deposited Energy Ratio （NCDER） is a new method that is proposed to reconstruct incidence position in a single layer for a 3-dimensional imaging electromagnetic calorimeter （ECAL）. This method was applied to reconstruct the ECAL test beam data for the Alpha Magnetic Spectrometer-02 （AMS-02）. The results show that this method can achieve an angular resolution of 7.36±0.08°/√E＋0.28±0.02° in the determination of the photon＇s direction, which is much more precise than that obtained with the commonly-adopted Center of Gravity （COG） method （8.4±0.1°/E＋0.8±0.3°）. Furthermore, since it uses only the properties of electromagnetic showers, this new method could also be used for other type of fine grain sampling calorimeters.     

用最小电离的质子刻度铅–闪烁光纤夹层电磁量能器

研究利用最小电离的质子和已知能量的电子来刻度铅–闪烁光纤夹层电磁量能器.对最小电离粒子输出响应进行光纤衰减修正后,利用最小电离质子的输出响应对量能器测量单元进行标定,然后对不同入射能量的电子事例进行能量重建,重建能量与入射能量有很好的线性关系.本文还对最小电离的质子与μ子对量能器测量单元的输出响应进行了比较,发现二者在误差范围内是一致的.     

Study of new boson W_1~± in the Minimal Higgsless Model at the LHC

The Minimal Higgsless Model predicts the existence of new vector gauge boson W1± . By the process PP → W1± qq → W±Z0qq, Z0 → l+l-, W±→ qq (l=e,μ; q is hadronized to be jets), we study the sensitivity of searching for this possible vector gauge boson in the level of generator events of signal and backgrounds, then give integrated luminosity required to discover 5σ signal as a function of W1± mass. The generator for the signal PP→W1± qq→W±Z0qq at tree level is developed with the Minimal Higgsless Model and th...     

CT重构中射线硬化的校正研究

在工业CT(ComputedTomography)重构中,由于射束硬化使得重建图像中出现"杯状"伪影。为了消除这种影响,提出了一种校正方法。该方法基于Beer理论,根据多色射束和数据,首先拟合出等效单色射束和数据,然后进行卷积反投影重构。这种方法不仅较好地消除了射线硬化的影响,同时也使重构图像的信息损失不大。     

ICT并行重建算法设计与实现

分析了三维ICT近似重建FDK快速算法以及算法串行执行与并行执行的复杂度,利用MPI并行编程环境,对原有ICT重建流程进行并行化,在PC集群上实现了并行ICT重建,进行了系统集成。给出了系统应用实现的解决方案与软件集成流程图。实验结果证明串行重建和并行重建结果是一致的,并行重建可以得到比较理想地重建时间结果和比较理想的加速比与效率。     

可见光催化烷基磺酰自由基启动芳酰肼的烷基磺酰化反应

鉴于磺酰基在有机分子中的重要意义,磺酰基的引入与磺酰化合物的合成被广泛报道.其中,磺酰肼化合物因在抗肿瘤、抗菌等方面表现出的生物活性,其相关合成备受关注,本工作发展了可见光照射下烷基三氟硼酸钾、DABCO·(SO2)2(1,4-Diazabicyclo[2.2.2]octane,DABCO)和芳酰肼的有机光反应,一锅法...     

增强型电场协助光催化降解有机污染物

以颗粒状ＴｉＯ２为光催化剂,以工苯酚溶液的降解为模型反应,实现了在电场协助下三维光电组合仙化反应,实验发现,在相同的反应条件下,电解反应和光催化反应中苯酚的降解率分别为１０％和３３．６％,而光电组合催化过程中苯酚的降解率为８２．８％,存在明显的协同作用,产生这种协同作用的主要原因是,电解水反应可有效地为光催化反应提供氧源,以及阳极偏压可有效地减少光生电子和空穴的复合,此外,还研究了电量和溶液酸碱性     

Application of the parametric for mulae for electromagnetic showers in unconverted γ/π~0 discrimination

In the LHC experiment, the neutral pions produced during jet fragmentation are the background sources for all physics channels with high-energy photons in their final state. In this paper, the application of the three-dimensional parametric formula for electromagnetic (EM) showers, which we developed in the Alpha Magnetic Spectrometer II experiment, is presented to distinguish the unconverted photons from the neutral pions. With the constructed electromagnetic calorimeter (ECAL) in a GEANT4 simulation, the parametric formulae were validated and the unconverted γπ⁰ discrimination was performed with the Toolkit for Multivariate Data Analysis (TMVA) package in ROOT for different transverse energies ranging from 15 GeV to 75 GeV, which is the most sensitive region for light Higgs (with mass ～120 GeV) searches with the channel H→γγ. With this discrimination method and the selected transverse energy region, we can reject π⁰ with the efficiency from ～40% (65--75 GeV) to ～90% (15--25 GeV) when keeping 90% γ efficiency.