On double polarization asymmetries in the elastic electron-proton scattering

Double polarization asymmetry D_p^(M) for the process of elastic electroweak scattering of the longitudinally polarized electrons by polarized proton target is considered with account of anapole G_1p and electric dipole moment (EDM) G_2p proton form factors. This asymmetry is only due to T-parity violating form factor G_2p, but does not directly depend on it, and having a significant value, allows to confirm the existence of the EDM of the proton.     

Double scattering approximation of the atmospheric laser location equation taking polarization effects into account

An equation is obtained for the Stokes vector of radiation twice scattered in the backwards direction, assuming that the transmitter and receiver have small angular apertures, that the pulse length is short, and that the receiver and the transmitter are monostatically placed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 1, pp. 80–85, January, 1976.     

On the nuclear polarization potential for heavy-ion scattering

The real polarization potential ΔV due to transfer reactions is studied using a microscopic semiclassical formalism. It is found that ΔV is typically of the same order of magnitude as the corresponding absorptive potential W. Different types of possible energy dependences for ΔV and W are explored qualitatively. Specific calculations for ¹⁶O + ²⁰⁸Pb and ¹⁶O + ⁶⁰Ni scattering show features similar to those which have been deduced empirically.     

第二玻恩近似理论研究激光辅助e-Ar散射

在电子入射方向平行于激光场的极化方向这种特殊的散射模式下，应用第二玻恩近似(SBA)理论，分别利用含有极化势的静电屏蔽势和单纯的静电屏蔽势这两种原子势模型对激光场中电子-氩原子散射进行了研究，并与低频近似和实验数据进行了比较.结果表明，第二玻恩近似理论给出的结果与实验符合较好.另外，极化势在激光辅助电子-原子散射中起着重要作用. 关键词： 极化势 第二玻恩近似 微分截面 激光场     

Investigation of atmospheric aerosols based on polarization measurements and scattering simulations

For an ongoing project involving ocean color and temperature scanner and polarization and directionary of the earth’s reflectance onboard the advanced earth observing satellite, the radiance and degree of polarization of atmospheric aerosols were measured with a portable photopolarimeter (FPR2000) at wavelengths of 0.559, 0.760 and 0.811 μm. The observations were undertaken over the ocean around Shikoku Island of Japan on clear days with few clouds in July, 1995. The measurements were compared with simulations of polarization fields. This work also describes retrieval algorithms for aerosols. It is shown that: (1) the radiance decreases with wavelength, (2) oceanic type aerosols are available to evaluate the degree of polarization over the Pacific Ocean, and (3) polarization data in the Seto Inland Sea are explained by a water-soluble aerosol model.     

Analytical approximation for wavefunctions and computation of scattering rates in double heterojunction structures

An analytical approximation for wavefunctions in double heterojunction structures is proposed. Analytic expressions for the overlap integral and the matrix element for polar optical phonon scattering are derived. To test the validity of the expressions, the exact wavefunctions are obtained by solving Schrödinger's and Poisson's equations self-consistently. The coefficients in the analytic expression for wavefunctions are extracted from the exact wavefunctions and are subsequently used in analytic computation of the overlap integral and the matrix element mentioned earlier. For comparison, these quantities are also calculated numerically and the numerical and analytic results are shown to agree very closely with each other. It is also shown that the frequently used sine approximation for the wavefunctions results in substantial error.     

On the Fermi approximation in slow neutron scattering

In this paper a general connection between the scattering from a bound and a free nucleus is derived in terms of formal scattering theory. The basic idea is to eliminate the interaction Hamiltonian between neutron and nucleus. Then theT-operator for a bound nucleus can be expressed by that of the free nucleus and its binding potential. From this equation an expansion is given as a power series in the binding potential for the nucleus. For slow neutron scattering the first term of the series leads to Fermi's approximation. The second term is the first correction to Fermi's approximation which contains no divergences for point scatterers contrarily to theories of other authors. In particular the correction to Fermi's approximation of the scattering amplitude is calculated for an elastically bound proton in the limit of zero-energy neutron.     

On Born approximation in black hole scattering

A massless field propagating on spherically symmetric black hole metrics such as the Schwarzschild, Reissner–Nordström and Reissner–Nordström–de Sitter backgrounds is considered. In particular, explicit formulae in terms of transcendental functions for the scattering of massless scalar particles off black holes are derived within a Born approximation. It is shown that the conditions on the existence of the Born integral forbid a straightforward extraction of the quasi normal modes using the Born approximation for the scattering amplitude. Such a method has been used in literature. We suggest a novel, well defined method, to extract the large imaginary part of quasinormal modes via the Coulomb-like phase shift. Furthermore, we compare the numerically evaluated exact scattering amplitude with the Born one to find that the approximation is not very useful for the scattering of massless scalar, electromagnetic as well as gravitational waves from black holes.     

On the accuracy of the WKB approximation in optical dielectric waveguides

Eigenvalues and field distributions for optical waveguides obtained from the WKB approximation have been compared with those found from geometrical optics and from more rigorous weakly-guiding LP mode theories in the cases of the step-index and parabolic-index profiles. In all cases it is found that the zero-order WKB approximation yields very accurate eigenvalues provided care is taken in the choice of phase factors in the eigenvalue equation. Expressions are deduced for the required phase factors for guides of arbitrary index profile in both two- and three-dimensions, and physical interpretations are given in terms of ray optics. The first-order WKB field distributions are found to give good agreement with the mode fields everywhere except in the vicinity of the caustics.     

On the theory of polarization in nuclear reactions and scattering

A general treatment of polarization effects in two particle reactions is given. The treatment is in close analogy to the procedure presented by Welton, but treats the long ranged part of the Coulomb interaction separately. In this way the difficulties due to the slow convergence of the partial wave expansion for the Coulomb scattering amplitude are avoided. The results are readily applicable to scattering processes of both charged and uncharged particles.     

二次偏振调制测距系统中调制频率与测距精度的关系

本文在基于二次偏振调制激光测距系统的基础上, 对调制频率与激光测距系统精度的关系做了深入的理论推导和实验验证. 最终得出结论: 相位法激光测距系统的测量精度会随着调制频率的增大而提高, 且精度的提高程度正比于调制频率的不确定度Δf与测程范围内半波长数N值的比值. 并通过选取合适的调制频率来提高系统的测距精度, 提高后的测距精度可达10^-7.     

On the Born-Oppenheimer approximation of wave operators in molecular scattering theory

In this paper we study the diatomic molecular scattering by reducing the number of particles through Born-Oppenheimer approximation. Under a non-trapping assumption on the effective potential of the molecular Hamiltonian we use semiclassical resolvent estimates to show that non-adiabatic corrections to the adiabatic (or Born-Oppenheimer) wave operators are small. Furthermore we study the classical limit of the adiabatic wave operators by computing its action on quantum observables microlocalized by use of coherent states.     

Eikonal approximation for magnetic electron scattering

The eikonal (high-energy) approximation of Yennie et al. for the scattering of electrons from nuclei has been extended to include the transverse interaction, and in particular the case of magnetic scattering. It is applied here to elastic magnetic scattering from ²⁰⁹Bi at 500 MeV as an example.     

Finite-difference approximation for inverse scattering problem

For the first time potentials are reconstructed in a finite-difference approximation using a genuine inverse scattering method instead of multiple repeated solutions of a direct problem with iterative fitting of scattering data. Up to now a fundamental difference between spectral properties of the Schrödinger operator and its discrete analog hindered from doing this.     

On rigid projectile approximation in high energy nucleus-nucleus scattering

Rigid projectile approximation in high energy nucleus-nucleus collisions is discussed. The results are demonstrated ond- elastic scattering.Dedicated to Professor Ivan Úlehla on the occasion of his sixtieth birthday.     

Improvement of the Raman-Nath approximation for the resonant Kapitza-Dirac scattering

On the basis of the well-known Raman-Nath approximation, we have obtained a new analytical form for the amplitude of the resonant Kapitza-Dirac scattering of an atom in the field of counter-propagating laser pulses. Comparison of the obtained formula with that in the Raman-Nath approximation shows that the former describes, in addition to coherent diffraction, also channeling of atoms in a periodic field of counter-propagating laser pulses.     

ScattPy: A new Python package for light scattering computations

We present a Python package developed for computing optical properties of non-spherical particles. It gives a user friendly flexible framework that takes advantage of programming with the modern language supported by the abundant library of scientific packages. The framework is designed to include the methods and interfaces to third-party codes required to treat scatterers of different shape and structure. We describe the current state of our package called ScattPy, briefly outline its range of applicability and note its outstanding accuracy for inhomogeneous particles with a multilayered structure.We also demonstrate some advantages of the ScattPy in particular when performing large-scale computations. Such languages as Python are known to simplify the data input and allow one to include new classes and objects (e.g. those required to define new scatterer shapes) without recompiling the code. The main benefits come from their ability to organize easily the output data as a database. In the ScattPy we use the SQLite database and illustrate how it is utilized in our investigation of the phase function dependence on the shape, size and structure of spheroids. By comparing the time consumption of the ScattPy to that of an equivalent code written completely in FORTRAN we show that there can be no essential performance losses when using Python.