Повышение эффективности систем дистанционного радиационного контроля на базе линейного ускорителя электронов

The efficiency of the existing systems of introscopy, tomography and customs control is largely determined by the loss of quanta of bremsstrahlung radiation in systems to collimation, especially in the primary collimator. This article discusses a system of preliminary "cooling" of an electron beam and a decrease in the angular divergence of the flux of quanta due to multiple passes of the electron beam in a chamber placed in a transverse magnetic field. "Cooling" of the electron beam is provided by a special configuration of the magnetic field. In the proposed scheme, the phase portrait undergoes the simplest changes, namely, it increases abruptly in the foil, as if "stretching" in the vertical direction, but then, as it were, "rotates" around the origin, while reaching a horizontal position after "focusing". Thus, the transverse dimensions of the beam increase, and the angular spread, at least, does not increase, as without "cooling".

Rocking curve and spatial coherence properties of a long X-ray compound refractive lens

Semi-analytical theory of a long set of X-ray compound refractive lenses (CRLs) based on recurrence relations is developed further. The geometrical aperture, angular divergence of incident radiation and source size were accurately taken into account. Using this theory it is possible to calculate the width of the rocking curve of a long (40.7 cm) Be CRL which coincides with experimental data obtained earlier. By this approach the transverse coherence length for the X-ray beam after passing a set of CRLs of arbitrary complexity has been estimated. It is shown that at the focus this coherence length is equal to a diffraction-limited beam size (beam size in the case of a point source) and has minimal difference with the real beam size.

Means for generating ultra-wideb and radio-frequency emissions with semiconductor field generators

The paper considers the perspective of using powerful semiconductor subnanosecond electrical pulse generators as radiation modulators. We give the data on determining the amplitude-time and spectral radiation parameters of a synchronous active antenna array, the angular divergence of the array radiation. We also estimate the efficiency of converting the electric excitation energy of the antennas into the energy of the directed ultra-wideband radiation in the main directional lobe. Findings of the research show that the effective peak radiation power of the terawatt level is reached at the excitation power of the gigawatt level, and the effective average radiation power of tens of megawatts is achieved with the primary power consumption of modulators of tens of kilowatts.

X-ray investigation of strained epitaxial layer systems by reflections in skew geometry

Four different SiGe/Si layer structures, pseudomorphically grown and (partially) relaxed, are used as examples to demonstrate that reflections in symmetric skew geometry can successfully be used to realize a complex analysis of these systems. Taking the intensity exactly along the truncation rod of a reciprocal lattice point, it is possible to simulate this diffraction curve and determine the layer parameter in the projection according to the netplane tilt relative to the surface. The main precondition for this technique and for performing reciprocal space mapping with sufficiently high resolution is a low angular divergence of the incident and detected beams perpendicular to the diffraction plane, which can also be achieved by suitable optical elements on laboratory-based diffractometers.

Analytic expressions for the angular and the spectral fluxes at Compton X-ray sources

The goal of this paper is to express simply the number of photons impinging on a target in the framework of accelerator-based Compton X-ray sources. From the basic kinematics of Compton sources, analytic formulas for the angular and the spectral fluxes are established as functions of the energy spread or/and the angular divergence of the electron and the laser beams. Their detailed predictions are compared with Monte Carlo simulations. These analytic expressions allow one to compute in a simple and precise way the X-ray flux in a given angular acceptance and a given energy bandwidth, knowing the characteristics of the incoming beams.