二级π-核光学位及双电荷交换反应

本文采用π-核的Iso-elastic散射光学位框架,在纯核子机制下,考虑了核子关联,利用固定散射中心的场论方法微观地计算了二级光学位,并由此研究了到同位旋相似态的π-核双电荷交换(DIAS DCX)反应.本文计算的能区是:入射π介子的动能处于0～300MeV之间,在计算中同时考虑了π-核子散射振幅中s、p波分量的贡献.     

光折变晶体均匀多重全息图存储研究

本文推导了光折变晶体角度编码多重全息存储中写入均匀光栅时的曝光时间递推公式.分析了散射效应对光栅写入时间常数的影响和写入光耦合对光栅振幅的影响,给出了两种因素影响下曝光时间计算的修正递推公式.数值计算结果表明,按照这种修正公式计算所得多重存储中各幅全息光栅振幅不仅均匀性好,而且振幅相对较大,这种曝光方法有利于提高晶体的存储容量.实验中以递推公式所得时间进行曝光记录,在厚度为0.6mm的Fe:LiNbO₃晶体中采用角度编码很容易存储了30幅全息图.     

调制散射光束的振幅实现聚焦

光束通过生物组织白色涂料等散射介质后将发生散射,实现对散射光束进行整形和控制具有重要的意义。使用振幅调制实时反馈的方法,对入射到散射样品的相干光的振幅进行预调整,探测器实时读取散射光斑数据作为反馈依据,以此调制空间光调制器上的对应区域,进一步补偿由散射介质引起的振幅失调。实验结果表明,目标位置光强得到显著增加,其能量平均值是调制前散射区域能量平均值的11倍。     

基于PT对称高斯势的孤子单向散射的操控

本文运用数值模拟的方法讨论在PT对称高斯势中孤子的散射问题,包括演化动力学,孤子振幅和质心位置的传输动力学以及PT对称高斯势对孤子单向散射特性的影响.结果表明在一定的参数范围内,单个孤子或孤子串的散射都能展现出单向流的特性,并且可以通过适当地调节PT对称高斯势的参数来实现孤子单向散射的操控.     

非周期势散射波函数分析方法

本文发展了求解非周期势散射波函数的方法。对散射波函数进行的振幅与位相分析证实了这种方法的有效性。 关键词：     

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应用电子与多光子集团非线性Compton散射模型,将入射和散射光作为离子的传输机制,研究了Compton散射下多束相干强耦合激光等离子体中离子的运动,给出了相对论离子动力学方程,并进行了数值模拟。研究发现,散射使光的传播速度减小,系统的矢势和标势增大,由入射和散射光形成的多束相干强耦合激光能使质子加速到5.40GeV的能量,而耦合轴向电场在其中起着关键作用。     

Compton散射下等离子体中的离子加速

应用电子与多光子集团非线性Compton散射模型,将入射和散射光作为离子的传输机制,研究了Compton散射下多束相干强耦合激光等离子体中离子的运动,给出了相对论离子动力学方程,并进行了数值模拟。研究发现,散射使光的传播速度减小,系统的矢势和标势增大,由入射和散射光形成的多束相干强耦合激光能使质子加速到5.40GeV的能量,而耦合轴向电场在其中起着关键作用。     

激光场中电子自由—自由跃迁吸收截面

导出了激光场中电子被中心势场散射的以分波相移表示的自由-自由跃迁吸收截面理论计算公式,以激光场中慢电子被He原子势场散射为例做了计算,说明对于自由-自由吸收截面,该公式的计算是有效的、方便的。     

相对论性无自旋粒子在Hartmann势场中运动的精确解

在标量势等于矢量势的条件下,本文获得了具有Hartmann型势的Klein-Gordon方程的精确解.给出了束缚态的精确的能谱方程和归一化的径向波函数,对于散射态,获得了按“k/2π标度”归一化的径向波函数和相移的解析计算公式.讨论了散射振幅的解析性质和波函数、能谱方程以及相移的非相对论近似.     

Born近似散射幅的分波法推导

本文给出一种不同于通常教科书的推导散射振幅的Ｂｏｒｎ近似公式的方法．通过求解径向运动方程，我们得到了微扰的辏力场Ｕ（ｒ）产生的相移δｌ，再根据计算散射幅的分波法一般公式，并利用Ｇｅｇｅｎｂａｕｅｒ加法公式，推出了 Ｂｏｒｎ近似下的散射幅．     

Ballistic electron transport in wrinkled superlattices

Inspired by the problem of elastic wave scattering on wrinkled interfaces, we studied the scattering of ballistic electrons on a wrinkled potential energy region. The electron transmission coefficient depends on both wrinkle amplitude and periodicity, having different behaviors for positive and negative scattering potential energies. For scattering on potential barriers, minibands appear in the electron transmission, as in superlattices, whereas for scattering on periodic potential wells the transmission coefficient has a more complex form. Besides suggesting that tuning of electron transmission is possible by modifying the scattering potential via voltages on wrinkled gate electrodes, our results emphasize the analogies between ballistic electrons and elastic waves even in scattering problems on non-typical configurations.     

Inelastic shadowing effects in multiple scattering

The projectile-nucleon scattering amplitudes used as input into multiple scattering theories of projectile-nucleus scattering naturally include the effects of coupling to inelastic (i.e., production) channels. We employ a multichannel separable potential to describe the projectile-nucleon interaction and show that within the fixed nucleon framework we can obtain the nuclear elastic scattering amplitude. This includes terms outside the conventional formalisms, corresponding to intermediate propagation in the inelastic channels both above and below inelastic threshold. We refer to this as inelastic shadowing. In a two-channel approximation, we show that knowledge of the projectile-nucleon elastic scattering phase shifts plus specification of the inelastic threshold energy are sufficient to determine the off-shell coupled-channel transition matrix, implying that the nuclear amplitude can be calculated within this model without any detailed information about the inelastic channels. We study this solution quantitatively for some model problems and for pion scattering, with the general result that inelastic shadowing can be significant whenever the elementary interaction has important channel coupling. For pion scattering in the energy regime characterized by strongly absorptive resonances, we find, for example, that the effect of inelastic shadowing is much more important than that due to two-nucleon correlations.     

Approximate construction of the scattering amplitude from Mandelstam representation and elastic unitarity

An approximate expression for the scattering amplitude is derived from the Mandelstam representation and the elastic unitarity. To demonstrate our procedure in the relativistic case we considerπ-N scattering, omitting spin and isospin for simplicity. Non-relativistic potential scattering is discussed in detail.     

Path integral approach to electron scattering in classical electromagnetic potential

As is known to all, the electron scattering in classical electromagnetic potential is one of the most widespread applications of quantum theory. Nevertheless, many discussions about electron scattering are based upon single-particle Schrodinger equation or Dirac equation in quantum mechanics rather than the method of quantum field theory. In this paper, by using the path integral approach of quantum field theory, we perturbatively evaluate the scattering amplitude up to the second order for the electron scattering by the classical electromagnetic potential. The results we derive are convenient to apply to all sorts of potential forms. Furthermore, by means of the obtained results, we give explicit calculations for the one-dimensional electric potential.     

Quasiclassical green function in an external field and small-angle scattering processes

A representation is obtained for the quasiclassical Green functions of the Dirac and Klein-Gordon equations allowing for the first nonvanishing correction in an arbitrary localized potential which generally possesses no spherical symmetry. This is used to obtain a solution of these equations in an approximation similar to the Furry-Sommerfeld-Maue approximation. It is shown that the quasiclassical Green function does not reduce to the Green function obtained in the eikonal approximation and has a wider range of validity. This is illustrated by calculating the amplitude of small-angle scattering of a charged particle and the amplitude of Delbrück forward scattering. A correction proportional to the scattering angle was obtained for the amplitude of charged particle scattering in a potential possessing no spherical symmetry. The real part of the Delbrück forward scattering amplitude was calculated in a screened Coulomb potential.     

Oscillator potential from a bootstrap model of confined quarks

For a particular choice of the Bethe-Salpeter kernel and the confined quark propagator, we obtain a self consistent tent solution for the $\text{q}\text{q}$ scattering amplitude. The potential associated with this scattering turns out to be a harmonic oscillator potential.     

Surface-integral formulation of scattering theory

We formulate scattering theory in the framework of a surface-integral approach utilizing analytically known asymptotic forms of the two-body and three-body scattering wavefunctions. This formulation is valid for both short-range and long-range Coulombic interactions. New general definitions for the potential scattering amplitude are presented. For the Coulombic potentials, the generalized amplitude gives the physical on-shell amplitude without recourse to a renormalization procedure. New post and prior forms for the Coulomb three-body breakup amplitude are derived. This resolves the problem of the inability of the conventional scattering theory to define the post form of the breakup amplitude for charged particles. The new definitions can be written as surface-integrals convenient for practical calculations. The surface-integral representations are extended to amplitudes of direct and rearrangement scattering processes taking place in an arbitrary three-body system. General definitions for the wave operators are given that unify the currently used channel-dependent definitions.     

The local field correction to the optical potential at high energy

A key assumption in the derivation of the optical potential for high energy hadron-nucleus scattering is that no target nucleon is struck more than once. The local field (rescattering) amplitude gives the probability for the projectile to strike a target nucleon twice with an intermediate interaction with another nucleon. This rescattering amplitude generates a correction to the basic high energy optical potential, and it must be small for the above assumption to be valid. We evaluate the local field correction to the optical potential using the formalism of Foldy and Walecka. The projectile-nucleon potential is assumed to have a finite range, and the target nucleons are kept sufficiently far apart by a hard core correlation function that there is no overlap between target particles, and all off-energy-shell effects vanish. With a specific form for the high energy behavior of the on-shell projectile-nucleon scattering amplitude, we find that the local field correction vanishes rapidly at high energy.     

Scattering States of l-Wave Schrödinger Equation with Modified Rosen-Morse Potential

Within a Pekeris-type approximation to the centrifugal term, we examine the approximately analytical scattering state solutions of the l-wave Schrödinger equation with the modified Rosen-Morse potential. The calculation formula of phase shifts is derived, and the corresponding bound state energy levels are also obtained from the poles of the scattering amplitude.     

Magnus expansion and eikonal approximation in potential scattering

An expansion procedure due to Magnus is applied to the case of potential scattering. This technique, which is superior to the usual Born-Dyson expansion in that it preserves unitarity at each state, leads in first approximation to an expression for the scattering amplitude which contains as special cases the eikonal approximation and also the second Born approximation. In particular the first Magnus approximation provides a basis for the ad hoc addition of the real part of the second Born contribution to the eikonal scattering amplitude as was considered by Byron et al.