Design and performance of coded aperture optical elements for the CESR-TA x-ray beam size monitor

TL;DR

This paper discusses the design and testing of coded aperture optical elements for an x-ray beam size monitor at CESR-TA, enabling precise, turn-by-turn measurements of electron and positron beam sizes.

Contribution

It introduces tunable coded aperture optical elements optimized for high-resolution, real-time beam size measurements in a storage ring environment.

Findings

Optical elements achieve accurate beam size measurements of 10-100 μm.

Model predictions closely match experimental performance.

Tunable slit patterns improve resolving power.

Abstract

We describe the design and performance of optical elements for an x-ray beam size monitor (xBSM), a device measuring $e^+$ and $e^-$ beam sizes in the CESR-TA storage ring. The device can measure vertical beam sizes of $10-100~\mu$m on a turn-by-turn, bunch-by-bunch basis at $e^\pm$ beam energies of $\sim2-5~$GeV. X-rays produced by a hard-bend magnet pass through a single- or multiple-slit (coded aperture) optical element onto a detector. The coded aperture slit pattern and thickness of masking material forming that pattern can both be tuned for optimal resolving power. We describe several such optical elements and show how well predictions of simple models track measured performances.