Development of Nanometer-scale Stabilization at the Interaction Point of the ATF2 Final Focus Prototype at KEK ( Japan)
Abstract
The ATF2 final focus prototype features an ultra-low emittance beam focused down to a less than 40 nm vertical beam size at the focal point. The development of dedicated instrumentation enabling the fluctuations of the beam to be measured with a few nm accuracy, as input to a feedback control loop, is reported. A set of special low-noise cavity-BPMs has been prepared with a decay constant short compared to the 300 ns time separation of ILC-like bunch trains which will be used. Installation is planned in a new vacuum vessel, custom made to provide adjustment capabilities in three dimensions for in situ relative alignment and calibration purposes. A fast kicker and feedback algorithm are in preparation for deployment later in the year.