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We present the distorted wave Born approximation (DWBA) for electron impact excitation and a method to calibrate the DWBA. With the calibrated DWBA, the differential cross sections (DCS) for excitation of H and He + from 1s to 2s and 2p are calculated and the results are compared with the absolute experimental measurements for H at incident energies of 50 eV and 100 eV. It has been found that the theoretical results are in very good agreement with the experiment, which confirms the validity of the calibration procedure. This work prepares an efficient theoretical method for numerical simulations of non-sequential double ionization of He in strong laser pulse in which laser-induced electron impact excitation of He + is involved.

A high speed 8B/10B Encoder/Decoder is presented in this paper. The Encoder/Decoder is based on Altera’s low cost FPGA Cyclone family. The Encoder/Decoder includes parallel pipeline structure. The Encoder/Decoder is applied to the Serializer/Deserializer (SERDES) of high-speed serial bus. The Encoder/Decoder is synthesized and simulated by Quartus II 9.1. The synthesis and analysis results show the maximum frequency is more than 359MHz. The timing simulation results show the clock frequency is more than 125 MHz. The single channel data rate of serial bus can get to 1.25Gbps. The proposed Encoder/Decoder can meet the requirements of most high-speed serial bus.

Aiming at the time redundancy in the flat panel display (FPD) imaging process, the paper studied some problems for FPD gray scale controlling based on the fractal theory, dissertates the construction of the space-time mapping topology architecture, the proposition of optimal scanning structure for FPD’s gray imaging, and the creation of the fractal theoretic model. Then the logic implementation and system application are presented based on the fractal model of the optimal scan architecture, and the application results achieved target of eliminating time redundancy and increasing the scanning availability. The novel control mode that the fractal scanning IP core described with Verilog language embedded in the FPGA hardware frame can efficiently increase the imaging gray scales and quality in the FPDs scanning controller and speed up the frame frequency of display system.

Laser-induced electron diffraction (LIED), in which elastic scattering of the returning electron with the parent ion takes place, has been used to extract atomic potential and image molecular structures with sub-A precision and exposure time of a few femtoseconds. So far, the polarization and exchange effects have not been taken into account in the theoretical calculation of differential cross section (DCS) for the laser-induced rescattering processes. However, the validity of this theoretical treatment has never been verified. In this work, we investigate the polarization and exchange effects on electron impact elastic scattering with rare gas atoms and ions. It is found that, while the exchange effect generally plays a more important role than the polarization effect in the elastic scattering process, the exchange effect is less important on electron–ion collisions than on electron–atom collisions, especially for scattering in backward direction. In addition, our calculations show that, for electron–atom collisions at incident energies above 50 eV, both the polarization and exchange effects can be safely neglected, while for electron–ion collisions, both the polarization and exchange potentials do not make substantial contributions to the DCS at incident energies above 20 eV and scattering angles larger than 90°. Our investigation confirms the validity of the current LIED method.

The laser-assisted radiative capture between a positron and an antiproton is studied in detail. The theoretical results show that the cross-section for antihydrogen formation is significantly reduced with the application of a laser background. This effect is most marked when the laser polarization is parallelto the incident direction.

We investigate the target and intensity dependence of plateau in high-order above threshold ionization (HATI) by simulating the two-dimensional (2D) momentum distributions and the energy spectra of photoelectrons in HATI of rare gas atoms through using the quantitative rescattering model. The simulated results are compared with the existing experimental measurements. It is found that the slope of the plateau in the HATI photoelectron energy spectrum highly depends on the structure of elastic scattering differential cross section (DCS) of laser-induced returning electron with its parent ion. The investigations of the long- and short-range potential effects in the DCSs reveal that the short-range potential, which reflects the structure of the target, plays an essential role in generating the HATI photoelectron spectra.

We use the strong field approximation with a time window function controlling the release time of electrons to study the intra-cycle and inter-cycle interferences in few-cycle intense laser pulses impinging on He. The diffraction fringes, i.e., the vertical stripe-like structure, observed in the experimental two-dimensional photoelectron momentum distributions of Gopal et al. (2009 Phys. Rev. Lett. 103 053001) have been attributed to the interplay of the intra- and inter-cycle interferences. The pure numerical calculations by solving the time-dependent Schrodinger equation are also performed and the results are compared with the experimental measurements directly. It has been found that the position of the stripe-like structure can be used to determine the duration of the laser pulses used in experiments.

Within the framework of the first-order Born approximation, the triple differential cross sections (TDCSs) for simultaneous ionization and excitation of helium are calculated. The wave function of the ejected electron is chosen to be orthogonal or non-orthogonal to the wave function of the bound electron before ionization. It is found that the orthogonality has a strong effect on the TDCS, especially when plane waves and Coulomb waves are used to describe the projectile and the ejected electron.

We point out that the conclusion of the preceding comment on antihydrogen formation in laser-assisted antiproton-positronium collision [preceding Comment, Phys. Rev. A 61] is invalid for an intense field case, and show that the positronium will not be broken up by the laser before the collision takes place in the suggested experimental setup. Thus we cannot rule out the possibility of the cross-section enhancement for such a laser-assisted reaction.

This paper presents the design and logic implementation of the fractal scan algorithm based on the mathematical model of the optimal scan architecture. Through the exploration of the sub-space code sequences and bit code sequences for different grey levels, we deduce the general formulae for the sequences and propose the corresponding logic implementations including the fractal scanning IP core and the general grey-level controller for Flat Panel Display (FPD). The parameterised IP core for various grey levels, embedded in FPD scan controller, can efficiently increase the scan utilisation and imaging quality. This research provides a new engineering way to solve a pressing problem of high resolution FPD technology. [Received 28 January 2010; Revised 7 July 2010; Accepted 18 December 2010]

In the first Born approximation, antihydrogen formation in the laser-assisted collision between an antiproton and a positronium is studied. It is found that the antihydrogen formation cross section is notably enhanced at lower impact energy due to the laser modification. For a geometry of laser polarization parallel to the incident direction, the result is modified to the maximum.