Submicron X-ray microbeam production with a Wolter-type grazing incidence mirror at Tristan Main Ring (KEK)

Tristan Main Ring (MR) at KEK in Japan was temporarily operated as a synchrotron radiation source from September to December in 1995. The machine was operated at 8Gev and the beam current was several mA during our experiment. Although our machine time was limited to only five days, the results were very useful. A quasi-monochromatic beam from the undulator was monochromatized by two silicon parallel crystals. An 8.5keV monochromatic X-ray beam was focused by the Welter-type grazing incidence mirror which consists of paraboloidal and hyperboloidal inner surfaces. The distance between the undulator and the mirror was 100m, which gave rise to a relatively large coherent area (vertical similar to 50 mu m, horizontal similar to 30 mu m) at the entrance plane of the mirror. A highly collimated beam (vertical divergence similar to 3 mu rad, horizontal similar to 5 mu rad) was so sensitive to the mirror surface undulation that several focal spots were produced. The shape of the spots were nearly elliptical. The smallest diameter of the spots was less than 1 mu m.