KEKにおけるレーザーコンプトン散乱を用いた小型Ｘ線源の開発の現状とアップグレード計画

抄録

We have developed a compact X-ray source via inverse Compton scattering between an electron beam and a laser pulse stacked in an optical super-cavity at Laser Undulator Compact X-ray (LUCX) accelerator in KEK. The accelerator consists of a photo-cathode RF-gun, an S-band accelerating tube and a part of X-ray generation. In the autumn of last year, we have succeeded in taking X-ray images of fish bone and etc. However, it had taken two hours to get an X-ray image because of low intensity of X-ray with the number of 10⁴ photons/train. In order to obtain a clear X-ray image in a shorter period of time, we are planning to increase the intensity of X-ray to 450 times. To achieve this aim, the number of electron bunches is extended to 1000 bunches/train and the stacked laser power in the optical cavity is increased to 15 times. In order to avoid the mirror damage, the laser spot size on the mirror will be expanded by lengthening the distance between mirrors. Moreover, the collision angle is reduced from 20° to 7.5°. By carrying out these improvements, the expected number of X-ray photons will increase to 1.7×10⁷ photons/train. In this upgrade, a 3.6 cell rf-gun, a 12 cell booster and a planner type four-mirror cavity will be newly installed. In this paper, the experimental results of X-ray imaging in last autumn and the upgrade plan of the LUCX accelerator will be reported.