Nonlinear Propagation of Coupling Optical Pulse under Compton Scattering in Laser Medium

After considering Kerr nonlinear effect,group velocity dispersion of host and gain distribution of active particle in laser amplifying medium,a basic equation describing propagation of the coupling optical pulse under the multi-photon nonlinear Compton scattering in the laser amplifying medium has been deduced. Besides,the profile and power spectrum of a picosecond-level super-Gaussian coupling pulse in the laser amplifying medium have been discussed when its central frequency coincides with the gain peak frequency of the laser amplifying medium.     

反散射数字辐射成像系统

反散射成像法是数字辐射成像的主要方法之一，介绍了获得反散射数字图像的实验装置，并着重分析了针对此装置获得的反散性图像的处理方法。     

X射线ICT检测中康普顿散射效应的影响与修正

在X射线工业计算机层析检测(ICT)中,由于X射线与物质作用发生康普顿散射效应,有用信息连同散射光子一起进入探头形成伪影。运用康普顿散射强度方程,结合X射线与物质相互作用的特性,推出X射线ICT中的散射修正公式,并由圆形截面工件散射模型,求出圆形截面工件的具体计算积分限。从探测器探测到的总光子数中减去康普顿散射光子数,即可有效去除散射光子造成的伪影。     

康普顿背散射图像重建算法的GPU加速研究

在康普顿背散射成像中,射线源和探测器放置于物体同侧,无需旋转即可重建出物体内部断层图像。但康普顿背散射图像重建算法计算复杂度较高,重建耗时较长。根据康普顿背散射图像有序子集最大期望法(ordered subsets expectation maxization,OSEM)重建算法的执行特点,设计了适合算法正投影和反投影的并行策略进行GPU加速。重建结果表明,所使用的加速策略能够在保证重建图像质量的同时获得较高的加速比。     

Compton profiles of MoP and WP: Validation of second order generalized gradient approximation

Recently, Zhao and Truhlar (J. Chem. Phys. 128, 184109, 2008) have constructed second order generalized gradient approximation (SOGGA) within the density functional theory. The authors have successfully tested the performance of SOGGA by computing lattice constants, cohesive energies, bond distances and few energetic quantities of different solids and molecules. In this paper, to establish the usefulness of SOGGA in deducing the momentum densities, we have compared our experimental Compton profiles of MoP and WP with those computed using GGA and SOGGA within density functional theory. It is seen that SOGGAPBE based Compton profiles of both the samples are in better agreement with the corresponding experimental data than those derived from BPBE-GGA. In addition, energy bands, density of states and relative nature of bonding in both the phosphides is explained in terms of equal-valence-electron-density profiles and Mulliken’s population analysis.     

Effect of Gas Velocity on the Dust Sediment Layer in the Coupled Field of Corona Plasma and Cyclone

A dust sediment layer was found on the outer tube wall when the ESCP （electrostatic centrifugal precipitator） trapped diesel particulates or ganister sand. The Compton back scatter method was used to measure the sediment thickness during the experiment. The effect of the inlet gas velocity on the dust sediment layer was investigated. PIV （Particle Image Velocimetry） was used to measure the velocity field between the inner barb tube wall and the outer tube wail. Experiments showed that the thickness of the sediment increased with time, and the sediment layer at the lower end was much thicker than that at the upper end. The agglomeration on the outer tube wall could be removed when the inlet gas velocity was increased to a certain value.     

Photon Polarization in Photonic Crystal Fibers under Compton Scattering

Using the quantum invariant theory and unitary transformation means, we study the influences of multi-photon nonlinear Compton scattering on the photon polarization in photonic crystal fibers（PCF）. The results show that the photon polarization of the incident photon changes a lot due to scattered optical, and its general geometric phase factor, Hamiton number and evolution operator are definited both by the incident and scattered optical.     

X-ray Compton scattering tomography

We lay the foundations for a new fast method to reconstruct the electron density in X-ray scanning applications using measurements in the dark field. This approach is applied to a type of machine configuration with fixed energy sensitive (or resolving) detectors, and where the X-ray source is polychromatic. We consider the case where the measurements in the dark field are dominated by the Compton scattering process. This leads us to a 2D inverse problem where we aim to reconstruct an electron density slice from its integrals over discs whose boundaries intersect the given source point. We show that a unique solution exists for smooth densities compactly supported on an annulus centred at the source point. Using Sobolev space estimates, we determine a measure for the ill posedness of our problem based on the criterion given by Natterer ("The mathematics of computerized tomography" SIAM 2001). In addition, with a combination of our method and the more common attenuation coefficient reconstruction, we show under certain assumptions that the atomic number of the target is uniquely determined. We test our method on simulated data-sets with varying levels of added pseudo random noise.     

Compton散射下的3阶色散对超短光孤子脉冲自频移的影响

应用多光子非线性Compton散射模型,对Compton散射下的3阶色散对超短光孤子脉冲自频移的影响进行了研究,通过理论分析、数值模拟和拟合,结果表明,Compton散射使3阶色散对孤子自频移有较强的抑制作用,在时域中引起孤子脉冲的调制振荡结构更为明显,频域中的频谱被分为两个较清晰的、峰值较高的谱峰,孤子自频移 ,但其斜率不同于散射前的斜率。