Improvement of the Resolution of SR Interferometer at KEK-ATF Damping Ring

Some of the improvement were done for an SR interferometer with the Herschelian reflective optics*. Previously, the measured vertical beam size was limited to around 5μm with a double slit separation of 40mm and wavelength of 400nm at the ATF damping ring. Double slit separation was mainly limited to the effective aperture of the optical path between the source point and interferometer. This time, we re-aligned the optical path, and as a result, the effective aperture was increased. Using this re-alignment we can have a double slit separation of up to 60mm. To reduce air turbulence, the optical path was covered with a tight air duct. After these improvements were made, we succeeded in measuring a vertical beam size of 3.4μm with double slit separation of 60mm and wavelength of 550nm, which corresponds to 5pm of the vertical emittance assuming 3m of the beta function.
Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan