• P. Burrows, R. Apsimon, D.R. Bett, G.B. Christian, B. Constance, H. Dabiri Khah, C. Perry, J. Resta-López, C. Swinson
  JAI, Oxford

We present the design of a stripline beam position monitor (BPM) signal processor with low latency (c. 10ns) and micron-level spatial resolution in single-pass mode. Such a BPM processor has applications in single-pass beamlines such as those at linear colliders and FELs. The processor was deployed and tested at the Accelerator Test Facility (ATF2) extraction line at KEK, Japan. We report the beam test results and processor performance, including response, linearity, spatial resolution and latency.

• J. Resta-López, R. Apsimon, P. Burrows, G.B. Christian, B. Constance
  JAI, Oxford
• J. Alabau-Gonzalvo
  IFIC, Valencia

The commissioning of the ATF2 final focus test beam line facility is currently progressing towards the achievement of its first goal: to demonstrate a transverse beam size of about 40 nm at the focal point. In parallel, studies and R&D activities have already started towards the second goal of ATF2, which is the demonstration of nanometer level beam orbit stabilization. These two goals are important to achieve the luminosity required at future linear colliders. Beam-based intra-train feedback systems will play a crucial role in the stabilization of multi-bunch trains at such facilities. In this paper we present the design and simulation results of beam-based intra-train feedback systems at the ATF2: one system located in the extraction line at the entrance to the final focus, and another at the interaction point. The requirements and limitations of these systems are also discussed.

• P. Burrows, R. Apsimon, D.R. Bett, G.B. Christian, B. Constance, H. Dabiri Khah, C. Perry, J. Resta-López, C. Swinson
  JAI, Oxford

We present the design and beam test results of a prototype beam-based digital feedback system for the Interaction Point of the International Linear Collider. A custom analogue front-end signal processor, FPGA-based digital signal processing boards, and kicker drive amplifier have been designed, built, deployed and tested with beam in the extraction line of the KEK Accelerator Test Facility (ATF2). The system was used to provide orbit correction to the train of bunches extracted from the ATF damping ring. The latency was measured to be approximately 140 ns.

• J. Resta-López, P. Burrows
  JAI, Oxford

The design luminosity of the future linear colliders requires transverse beam size at the nanometre level at the interaction point (IP), as well as stabilisation of the beams at the sub-nanometre level. Different imperfections, for example ground motion, can generate relative vertical offsets of the two colliding beams at the IP which significantly degrade the luminosity. In principle, a beam-based intra-train feedback system in the interaction region can correct the relative beam-beam offset and steer the beams back into collision. In addition, this feedback system might considerably help to relax the required tight stability tolerances of the final doublet magnets. For CLIC, with bunch separations of 0.5 ns and train length of 156 ns intra-train feedback corrections are specially challenging. In this paper we describe the design and simulation of an intra-train feedback system for CLIC. Results of luminosity performance simulation are presented and discussed.