Realign the final focus beamline and remove beam dump shield

We aim to establish techniques to realize the nanometer beam size and its position stabilization at the final-focus beamline called ATF2 in KEK-ATF for ILC. ATF2 beamline was built as additional beamline in 2008. Beamlines of ATF2 and Dumping Ring (DR) are set on different floor blocks. Early September in 2018, we removed an iron shield used by previous beam dump located between ATF2 and DR and 2m from beamline. It weighs 62.5t and has been surveyed and confirmed to influence the position of the beamline. As a result, a remarkable ascent of 600 μm was confirmed in the vertical direction, and had proceeded an alignment of the whole ATF2 beamline to minimize the influence. Magnet movers are installed to ATF2 beamline. Usually, The movers feed back the beam response to align to the optimal beam trajectory position in operation. We confirmed the operation of one of the movers. Hence, this paper reports the results of fine-alignment of ATF2 beamline and movement of magnet mover without feedback. (author)