Abstract
A high-resolution, intratrain position feedback system has been developed to achieve and maintain collisions at the proposed future electron-positron International Linear Collider (ILC). A prototype has been commissioned and tested with a beam in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization in Japan. It consists of a stripline beam position monitor (BPM) with analogue signal-processing electronics, a custom digital board to perform the feedback calculation, and a stripline kicker driven by a high-current amplifier. The closed-loop feedback latency is 148 ns. For a three-bunch train with 154 ns bunch spacing, the feedback system has been used to stabilize the third bunch to 450 nm. The kicker response is linear, and the feedback performance is maintained, over a correction range of over $\pm$60 {\mu}m. The propagation of the correction has been confirmed by using an independent stripline BPM located downstream of the feedback system. The system has been demonstrated to meet the BPM resolution, beam kick, and latency requirements for the ILC.
Highlights
The International Linear Collider (ILC) [1] is a proposed high-luminosity electron-positron collider (Fig. 1) with a baseline center of mass (c.m.) energy of 500 GeV and options for operating within the c.m. energy range between 250 and 1000 GeV
A schematic of the proposed intratrain interaction point (IP) feedback system for correction of the relative vertical beam misalignment is shown in Fig. 2 for the case in which the two beams cross with a small horizontal angle; the ILC design incorporates a crossing angle of 14 mrad
A prototype of such a feedback system has been developed by the Feedback on Nanosecond Timescales (FONT) group [16] and has been installed, commissioned, and tested at the Accelerator Test Facility (ATF) [17] at the High Energy Accelerator Research Organization (KEK)
Summary
The International Linear Collider (ILC) [1] is a proposed high-luminosity electron-positron collider (Fig. 1) with a baseline center of mass (c.m.) energy of 500 GeV and options for operating within the c.m. energy range between 250 and 1000 GeV. A schematic of the proposed intratrain IP feedback system for correction of the relative vertical beam misalignment is shown in Fig. 2 for the case in which the two beams cross with a small horizontal angle; the ILC design incorporates a crossing angle of 14 mrad. Such a large outgoing beam deflection angle causes beam position displacements of up to 1400 μm in a beam position monitor (BPM) placed ∼4 m downstream of the IP as in the ILC design [1]. The kicker is required to have sufficient drive to correct an IP relative bunch offset of up to Æ200 nm which, for the ILC final focus magnets, sets an ∼ Æ 60 nrad kick range requirement for a 250 GeV beam
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