Compton scattering opacity

We show first that there is an error in the literature in the evaluation of the Compton scattering opacity; second, we compare the corrected values with the published ones and, third, we show that two commonly made approximations are inaccurate in the case of electron degeneracy.     

Compton scattering from isotropic electrons

The exact Compton cross section for scattering of photons from isotropic monoenergetic electrons is given in analytical form. It is shown that the moments of the Legendre expansion of the scattering kernel can be obtained analytically, apart from an integration over the unknown electron distribution function.     

Compton scattering on208Pb

In this paper we briefly review the formalism of the nuclear Compton scattering in the frame of the low-energy theorems (LET). We treat the resonant terms of the amplitude, having collective intermediate nuclear states, as a superposition of Lorentz lines with energy, width and strength fixed by the photo-absorption experiments. The gauge terms are evaluated starting from a simple, but realistic, nuclear Hamiltonian. Dynamical nucleon-nucleon correlations are consistently taken into account, beyond those imposed by the Pauli principle. The comparison of the theoretical predictions with the data of elastic diffusion of photons from²⁰⁸Pb shows that LET are insufficient to account for the experiment.     

康普顿散射中反冲电子方向的正确画法

指出了某些教材中康普顿散射示意图画法的不妥之处,并严格推导了康普顿散射中反冲电子的散射角,给出了正确的康普顿散射示意图.     

Aspects of nucleon Compton scattering

We consider the spin-averaged nucleon forward Compton scattering amplitude in heavy baryon chiral perturbation theory including all terms to order . The chiral prediction for the spin-averaged forward Compton scattering amplitude is in good agreement with the data for photon energies110 MeV. We also evaluate the nucleon electric and magnetic Compton polarizabilities to this order and discuss the uncertainties of the various counter terms entering the chiral expansion of these quantities.     

Pion Compton scattering in perturbative QCD

Pion Campton scattering is studied in perturbative QCD for real and space-like initial photons. Different methods for the convolution of the hard amplitude with the pion wave-functions, which have in the past led to conflicting results, are compared.     

Compton scattering in ignited thermonuclear plasmas

Inertially confined, ignited thermonuclear D-T plasmas will produce intense blackbody radiation at temperatures T greater, similar20 keV; it is shown that the injection of GeV electrons into the burning core can efficiently generate high-energy Compton scattering photons. Moreover, the spectrum scattered in a small solid angle can be remarkably monochromatic, due to kinematic pileup; a peak brightness in excess of 10;{30} photons/(mm(2) mrad(2) s 0.1% bandwidth) is predicted. These results are discussed within the context of the Schwinger field and the Sunyaev-Zel'dovich effect.     

Compton scattering and electron momentum distributions

The recent development of the technique of inelastic x-ray scattering to study the electron momentum distribution in the scatterer is surveyed. The simple relationship between the electron momenta and the Compton line shape in the impulse approximation is derived, and the validity of that approximation is discussed in the light of recent measurements. Current areas of research are reviewed.     

Isospin breaking in pion Compton scattering

Using chiral perturbation theory we calculate for pion Compton scattering the isospin-breaking effects induced by the difference between the charged and neutral pion mass. At one-loop order this correction is directly proportional to mp±2-mp02\ensuremath{m_{\pi^\pm}^2-m_{\pi^0}^2} and free of (electromagnetic) counterterm contributions. The differential cross-section for charged pion Compton scattering p-g? p-g\ensuremath{\pi^-\gamma \rightarrow \pi^-\gamma} gets affected (in backward directions) at the level of a few permille. At the same time the isospin-breaking correction leads to a small shift of the pion polarizabilities by d(ap- bp) @ 1.3 ·10-5\ensuremath{\delta(\alpha_\pi- \beta_\pi) \simeq 1.3 \cdot 10^{-5}} fm^3. In case of the low-energy gg? p0p0\ensuremath{\gamma\gamma \rightarrow \pi^0\pi^0} reaction isospin breaking manifests itself through a cusp effect at the p+p-\ensuremath{\pi^+\pi^-} threshold. We give an improved estimate for it based on the empirical p \pi p \pi -scattering length difference a0-a2\ensuremath{a_0-a_2} .     

Colour dipoles and virtual Compton scattering

An analysis of Deeply Virtual Compton Scattering (DVCS) is made within the colour dipole model. We compare and contrast two models for the dipole cross-section which have been successful in describing structure function data. Both models agree with the available cross section data on DVCS from HERA. We give predictions for various azimuthal angle asymmetries in HERA kinematics and for the DVCS cross section in the THERA region. Received: 22 July 2001 / Revised version: 5 November 2001 / Published online: 14 December 2001     

激光-电子康普顿散射物理特性研究

对激光-电子康普顿散射物理特性即能量特性和微分截面角分布进行了仔细的研究.计算结果显示出光子能量和微分截面角分布的简单结构.康普顿散射X射线光源具有散射光子的能量易调节、方向性好等特点.在入射电子束能量很高时,X射线近乎单向出射.光源色散度较大,但实验上可以获得色散（带宽）小的X射线.对于各种波长的激光,在很宽的电子束能量范围（1 MeV—10 GeV）内,散射X射线光子的总截面和前向发射圆锥内（半圆锥角1/γ,其中γ=E/m₀ 关键词： 康普顿散射 能量特性 微分截面 角分布     

Compton scattering study of orthorhombic sulphur

The Compton profiles of orthorhombic sulphur crystals have been measured the scattering vector perpendicular to the crystal planes (110) and (001) using 60 keV radiation from a ²⁴¹Am source. Significant anisotropy was observed in the electron momentum distribution. Fourier transformed Compton profiles were compared with theoretical autocorrelation functions for a S₈ ring molecule. It is shown that the observed anisotropy can be only partially interpreted in terms of intermolecular interactions. The strong correlation, observed in the direction perpendicular to the plane of the S₈ ring indicates a meaningful ring — ring interaction in the orthorhombic sulphur crystal.     

Deeply virtual Compton scattering off nuclei

We consider the hard leptoproduction of a photon off nuclei up to spin-1. As a new result we present here the general azimuthal angular dependence of the differential cross section for a spin-1 target. Its twist-two Fourier coefficients of the interference and squared deeply virtual Compton scattering amplitude are evaluated in leading order approximation of perturbation theory in terms of generalized parton distributions, while the pure Bethe-Heitler cross section is exactly calculated in terms of electromagnetic form factors. Relying on a simple model for the nucleon generalized parton distribution H, which describes the existing DVCS data for a proton target, we estimate the size of unpolarized cross sections, beam and longitudinal target spin as well as unpolarized charge asymmetries for the present fixed target experiments with nuclei. These estimates are confronted with preliminary HERMES data for deuterium and neon.Received: 1 October 2003, Published online: 3 December 2003     

Polarization and intensity of Compton scattering

X-ray spectra scattered at 90° by acrylic resin plates of various thicknesses are measured. The intensity and polarization of Compton-scattered X-rays are estimated from the spectra. As the thickness of the slab increases, the intensity increases but the polarization decreases. The optimal thickness for a polarized X-ray fluorescence spectrometer is determined, which provides both high intensity and high polarization.