FEATHER FEedback AT High Energy Requirements

Nicolas Delerue, Fujimoto Hiroyuki, Hayano Hitoshi, and Toshiaki Tauchi,
KEK
Contact

Purpose of FEATHER (short description)
Purpose of FEATHER (long description use published in the APPI proceedings)
Models of feedback
Presentation, publications and talks

Purpose of FEATHER

Ground motion at the Future JLC detector may affect beam alignement and cause huge luminosity loss. Here is presented a fast intrapulse feedback system that will address this problem by correcting the observed beam deviations.

Ground motion induced by both natural and human activities will induce fast changes in the position of the final focusing magnets of the future JLC (Japanese Linear Collider). Numerical simulations have shown that this can lead to an important luminosity loss.

The FEATHER system (FEedback AT High Energy Requirements\cite{feather}) addresses this issue by measuring the displacement of the first bunches of a colliding train and applying an appropriate correction.

FEATHER measures the offset of each beam after passing the interaction point (IP). The measured value is related to the incoming offset and is easier to measure as the beam as been deflected at the IP. From this value the required correction is estimated and applied to the incoming beam (see figure). As the beam offset is measured downstream the correction, the previously applied correction is memorized and applied once the corrected beam reaches the measurement location. Different designs have been proposed and tested at KEK, using the ATF (Accelerator Test Facility).

These designs show that luminosity loss due to ground motion can be reduced thanks to this system.

Models of feedback

Simple model with high capacitance kicker.
Simple model with low capacitance kicker.
Delayed model.
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