Electron Momentum Spectroscopy of Valence Orbitals of Cyclopentene:Nuclear Dynamics and Distorted Wave Effect

We report a measurement of electron momentum distributions of valence orbitals of cyclopentene employing symmetric noncoplanar(e,2e)kinematics at impact energies of 1200 and 1600 eV plus the binding energy.Experimental momentum profiles for individual ionization bands are obtained and compared with theoretical calculations considering nuclear dynamics by harmonic analytical quantum mechanical and thermal sampling molecular dynamics approaches.The results demonstrate that molecular vibrational motions including ring-puckering of this flexible cyclic molecule have obvious influences on the electron momentum profiles for the outer valence orbitals,especially in the low momentum region.Forπ^(*)-like molecular orbitals 3a′′,2a′′,and 3a′,the impact-energy dependence of the experimental momentum profiles indicates a distorted wave effect.

Relativistic and distorted wave effects on Xe 4d electron momentum distributions

The relativistic and distorted wave effects are investigated for the electron momentum distributions of Xe 4d electrons.The theoretical results show good agreements with the experimental data measured previously with electron momentum spectroscopy. The distorted wave effect and the relativistic effect are found to play important roles in the low and high momentum regions, respectively.

Possible generation of a γ-ray laser by electrons wiggling in a background laser

To extend the spectrum of lasers to the γ-ray range has been a dream for a long time for both nuclear and laser physi- cists. It means fantastic improvement of techniques, such as much more precise measurements of space-time, holography for nanometer size or even smaller objects, and so on. There are various proposals for its realization, including those of using nuclear decay and condensed positronium decay,

Quantum electrodynamics in a laser and the electron laser collision

Quantum electrodynamics in a laser is formulated, in which the electron–laser interaction is exactly considered, while the interaction of an electron and a single photon is considered by perturbation. The formulation is applied to the electron– laser collisions. The effect of coherence between photons in the laser is therefore fully considered in these collisions. The possibility of γ-ray laser generation by use of this kind of collision is discussed.

Positronium formation for positron scattering from metastable hydrogen

Positronium （Ps） formation for positron impact on metastable hydrogen in 2s state has been studied by using the two- channel, two-center eikonal final state-continuum initial distorted wave （EFS-CDW） method. The differential, integrated, and total cross sections for Ps formation in different states have been calculated from each channel opening thresholds to high energy region. The results are compared with other theoretical calculations available in the literature. For Ps formation in s-state at intermediate and high energies, our results are in good agreement with the prediction of distorted wave theory. Those formed in p-states and the total Ps formation cross sections are reported for the first time. It is shown that the total Ps formation cross sections for positron scattering from H（2s） state are significantly larger at relatively low energies, while smaller at high energies, compared with those obtained from hydrogen in ground state.

Electron Momentum Spectroscopy Study on Inner Orbitals of Methyl iodide

The binding energy spectrum and electron momentum profiles of the inner orbitals of methyl iodide have been measured using an electron momentum spectrometer at the impact energy of 1200 e V plus binding energy.Two peaks in the binding energy spectrum,arising from the spin-orbit splitting,are observed and the corresponding electron momentum profiles are obtained.Relativistic density functional calculations are performed to elucidate the experimental electron momentum profiles of two spin-orbit splitting components,showing agreement with each other except for the intensity in low momentum region.The measured high intensity in the low momentum region can be further explained by the distorted wave calculation.

Single ionization of helium atoms by energetic fully stripped carbon ions

A four-body distorted wave approximation is presented for theoretical investigations of the single ionization of groundstate helium atoms by fully stripped carbon ions at impact energies of 2 MeV/amu and 100 MeV/amu. The nine-dimensional integrals for the partial quantum-mechanical transition amplitudes of the specified reaction are reduced to some analytical expressions or one-dimensional integrals over real variables. Fully differential cross sections（FDCSs） are calculated and compared with their experimental values as well as the results obtained from other theories. Despite the simplicity and quickness of the proposed quadrature, the comparison shows that the obtained results are in reasonable agreement with the experiment and are compatible with those of other complicated theories.

Analysis of dispersion compensation for position-dependence in externally modulated CATV lightwave systems by using chirped fiber grating

The dispersion compensation characteristics of the chirped fiber grating （CFG） for different dispersion compensation positions are analyzed in externally modulated cable television （CATV） lightwave system and the analytic expression of the composite second order （CSO） distortion is derived. The analyses give a reasonable explanation for the position-dependent effect of CFG dispersion compensator, which was found in practical systems. Moreover, the theoretical result is also verified by an experiment. It is believed that the theory will be helpful in designing optical CATV fiber links with nodes at proper positions both for intensity amplification and dispersion compensation.

Thermal distortion and birefringence in repetition-rate plasma electrode Pockels cell for high average power

We numerically study thermally induced birfringence and distortion in plasma electrode Pockelscell based on KD^＊P as the electro-optic material. This device can repetitively operate underthe heat capacity mode.Simulation results indicate that the excellent switching performancesand low wave-front distortion are achieved within several tens seconds working time at averagepower in excess of 1 kW.

Rotation, scaling, and translation invariant local watermarking technique with Krawtchouk moments

A rotation, scaling, and translation invariant local watermarking is proposed with one or two Krawtchouk moment（s） of the original to estimate the geometric distortion parameters including rotation angle, scaling factor, and translation parameter. Krawtchouk moments can be used as private key of watermark extractor. Watermark is inserted into perceptually significant Krawtchouk moments of original, and watermark based on Krawtchouk moments is local. Independent component analysis （ICA） is utilized to extract watermark blindly. Experimental results show that this method has a good robustness against distortions preformed by watermark benchmark - Stirmark.

Image recognition of laser radar using linear SVM correlation filter

Through deducing the relationship between support vector machine （SVM） and correlation principle, the optimal hyperplane is proved as a correlation filter when the kernel function is the linear kernel. So a new correlation filter, named linear SVM correlation filter （LSCF）, is proposed. The filter has not only shift-invariance, but also SVM properties. The real images of laser radar are used as experiment data, and LSCF is used to solve the in-plane rotation invariance. The results show that the filter can recognize the different rotated objects, and the correlation output is stable. The filter is insensitive to the noise and gray change, and has good discrimination ability. In the same design way, LSCF is also suitable to solve other problems of correlation distortion.

High power pulse amplification of ytterbium-doped double-clad fiber amplifier

By solving a set of time-dependent equations, the characteristics of the ytterbium-doped double-clad fiber amplifier are presented. Besides the steady state in the fiber of the upper-state population, pump power and amplified spontaneous emission without the input signal, the dynamic characteristics of the high power Gaussian pulse amplification like the evolution of pulse waveform distortion, upper-state population distribution and stored energy and pulse energy of the amplifier under the forward and backward pump, are simulated. The relations between the output pulse energy of the amplifier and the different input pulse peak power or pump power are also discussed. The models and results can provide important guide for the design and optimization of the high power pulse amplification.

Experimental verification of combinational-deformable-mirror for phase correction

In adaptive optics （AO） system, the phase compensation capability is limited greatly by the actuator number of the deformable mirror （DM）. The actuator number of DM is mainly restricted by the manufacture techniques. The spatial correction capability of AO system can be improved by two or more combinational- DMs （CDMs） with conjugation relationship. The CDM AO system for wavefront correction is built, which consists of two 32-element DMs. The experimental results are in agreement with the numerical simulation results. It is indicated that the CDM AO system provides better correction performance than the single 32-element DM AO system.

Coarse error analysis and correction of a two-dimensional triangulation range finder

A real-time two-dimensional （2D） triangulation range finder is presented, which is composed of two linear complementary metal oxidation semiconductor （CMOS） chips, two camera lenses, and four light emitting diodes （LEDs）. The high order distortion in image aberrations is the main factor responsible for the coarse errors. The theoretical prediction is in good agreement with experiments and the correction equation is used to obtain more reliable results with the unique distortion coefficient in tile whole working region.

An electron momentum spectroscopic study of naphthalene in gas phase

We report the experimental and theoretical investigation of the complete valence shell binding energy spectra and momentum profiles of naphthalene (C 10 H 8),using our high resolution electron momentum spectrometer,at impact energies of 1500 eV and 600 eV.The observed momentum profiles were compared with the Hartree-Fock (HF) and density functional theory (DFT) calculations,and the binding energy spectrum was compared with the Outer valence Green's function (OVGF) calculations.The impact energy dependent discrepancy between observed momentum distributions and calculations under the plane wave impulse approximation was ascribed to the distorted wave effects.

核子电磁形状因子振荡行为的新视角

本文研究了质子和中子的类时电磁形状因子.作者基于手征有效场论,通过求解李普曼-施温格方程得到了核子-反核子对散射振幅.以此为输入,利用扭曲波恩近似方法描述了核子末态相互作用,计算了正负电子湮灭到正反核子对的过程.通过拟合相移、截面以及微分截面等实验数据,定下了有效场论的未知耦合常数.进一步研究发现,可以利用两个分数振荡振子来描述核子电磁类时形状因子的振荡行为:一个表现为过阻尼振荡,在阈值附近占主导地位;另一个类似于欠阻尼振荡,在高能区起到重要作用.这种振荡行为对理解硬光子诱导的核子内部极化电荷的分布起着至关重要的作用.