DEVELOPMENT OF HIGH BRILLIANT X RAY MICROBEAM BY A RESONANT TRANSITION RADIATION METHOD WITH A LOW ENERGY ELECTRON ACCELERATOR

用低能电子加速器共振跃迁辐射方法研制了高亮度X射线微束。结果表明：（1）光子能量为5 keV的共振跃迁辐射（RTR）X射线的亮度增加了60倍，达到约1×10^<14>Photons/（s mrad^2 mm^2 0. 1% b.w. mA）的椭圆型反射镜。大至10 nm的表面粗糙度不会降低反射镜的亮度。(2)光吸收-边缘跃迁辐射（TR）的方法通过倾斜薄箔堆来调谐，产生能量分辨率为10- 50%的准单色X射线。(3)通过矩形狭缝引出渡越辐射X射线，首次产生了近似线偏振的X射线束。测量的偏振线性度高于90%。(4)快电子从靶内表面发射的TR波的动态衍射，可以从根本上改变该波与晶体靶外表面发射的TR波之间的干涉。这种效应导致具有非常窄的角度和光谱宽度的动态TR峰的表现。获得了该峰的特征。(5)在晶体中的相对论粒子TR中可以观察到反常Borrmann吸收效应。这种预测的效果表现的条件已被考虑。(6)讨论了相对论粒子PXR沿发射电子速度沿着发射的最佳条件以及动态TR峰观测的条件。

A high brilliant x ray microbeam has been developed by using a resonant transition radiation method with a low energy electron accelerator. The obtained results are as follows :(1) The brilliance of the resonant transition radiation (RTR) X rays with a photon energy of 5 ke V increases by a factor of 60 and gets to a value of about 1×10^<14> Photons/(s mrad^2 mm^2 0.1%b.w. mA) by the ellipsoidal type mirror. The surface roughness as large as 10 nm does not decrease the brilliance for the mirror.(2) The method of photoabsorption-edge transition radiation (TR) tuned by tilting a thin-foil stack produces quasimonochromatic X rays with an energy resolution of 10-50%.(3) An almost linearly polarized X ray beam has been produced first by extracting transition radiation X rays through a rectangular slit. The measured linearity of the polarization is higher than 90%.(4) The dynamical diffraction of TR wave emitted by a fast electron from in surface of a target may change essentially interference between this wave and that emitted from out surface of a crystalline target. This effect causes the manifestation of a dynamical TR peak with very narrow angular and spectral width. Characteristics of such peak were obtained.(5) The effect of anomalous Borrmann absorption can be observed in a relativistic particle TR from a crystal. The conditions of this predicted effect manifestation have been considered.(6) The optimal conditions of a relativistic particle PXR emitted along an emitting electron velocity have been discussed as well as the conditions of a dynamical TR peak observation.