FIR SPECTROSCOPY AND BUNCH SHAPE MEASUREMENT BY COHERENT SYNCHROTRON RADIATION

利用东北大学核科学实验室的直线加速器，我们观察到了相干同步辐射的最基本特性。利用干涉仪观察干涉图样，观察了单束光波包的相干性，并利用高分辨率光谱仪确认了干涉引起的光谱精细结构。我们观察到平行金属板的屏蔽效应对相干辐射的抑制。从理论上对相干跃迁辐射的光谱强度、强度与发射长度的关系、强度的角分布等特性进行了较好的研究和分析。利用相干跃迁辐射，高分辨率地观察了玻璃材料固体试样在3mm长波段的透射率，并证实了在5mm长波段的透射率测量是可能的。利用100 ns的跃迁辐射脉冲和加速器的电子束，在0.2 ~几mm的波长范围内进行了高速辐射分解测量。通过对相干同步辐射和相干跃迁辐射的分析，证实了电子束的分布函数，其宽度为0.26 ~ 0.27 mm，几乎为高斯形状。分析了相干跃迁辐射的角分布，给出了光束的发射度。这些结果表明，相干辐射观测是一种具有皮秒级高分辨率的光束诊断新方法。

Using a linear accelerator at Laboratory for Nuclear Science, Tohoku University, We have observed most fundamental properties of coherent synchrotron radiation. We observed the coherence of the wave packet of light from individual bunches by the observation of interference pattern with an interferometer, and confirmed spectral fine structure due to the interference using a high resolution spectrometer. We observed the suppression of the coherent radiation by a shielding effect of parallel plates of metal. properties of coherent transition radiation such as the spectrul intensity, dependence of the intensity on the emission lengths, angular distribution of the intensity have also been investigated and analyzed well by theory.By the coherent transition radiation, the transmission of a solid state specimen of a glass material was observed with high resolution in the long wavelength region to 3 mm and the measurement of transmission was confirmed to be possible up to 5 mm. Using a 100 ns pulse of transition radiation and the electron beam from the accelerator, a high speed measurement of radiolysis was done in the wavelength range from 0.2 to a few mm.It has been confirmed that analysis of coherent synchrotron radiation and coherent transition radiation as well gives the distribution function of the electron in a bunch, which is of almost the Gaussian shape with the width of 0.26 to 0.27 mm. The analysis of the angular distribution of coherent transition radiation also gives the emittance of the beam. These results indicates that the observation of the coherent radiation is a new method of the beam diagnosis with a high resolution of picosecond.