Alignment of front end components at SPring-8

We review the alignment of front-end components at SPring-8. The front end is the part of a photon beamline, which is located between the photon beam port of the storage ring and the beryllium (Be) window assembly. The photon beam from a light source is guided to the optics hutch through the front end. We have constructed 43 front ends with the following design concepts; (1) use of a single common base (a pair of parallel I-beams), (2) employment of standardizing approach, and (3) independent units of pumping system. The alignment work has been performed in the procedure of inspecting the datum points on the floor, installation of the common base, and installation and alignment of components on the common base. This work has been successfully carried out with sufficient results. The alignment error of I-beams is about 50 micron in standard deviation. The components return to their original positions even if some displacements occur during baking procedures. We have had no serious troubles about the alignment works.