Measurement of Position Resolutions of L-band Cavity Beam Position Monitors

TL;DR

This paper reports on the development and testing of an L-band cavity beam position monitor designed for high-precision beam measurements in particle accelerators, achieving a projected resolution of about 300 nm.

Contribution

The paper introduces a prototype L-band cavity BPM and its signal processing system, along with a methodology for measuring position resolution at nanometer scales.

Findings

Projected position resolution of about 300 nm.

Identified problems and solutions in the measurement process.

Demonstrated the BPM's suitability for ILC beam requirements.

Abstract

Beam position monitors (BPMs) are indispensable components of modern particle accelerators, providing real-time diagnostics to ensure precise beam control, stability, and quality. As accelerators such as the International Linear Collider (ILC) aim for nanometer-scale beam sizes at the interaction point, stringent requirements on position resolution arise. Specifically, the main linac of the ILC demands a BPM resolution better than 5 {\mu}m to support stable beam transport and minimize emittance growth. To address this, we have developed an L-band cavity BPM optimized for the beam conditions of the ILC. In this paper, we introduce a prototype of an L-band cavity BPM and its signal processing system, describe the methodology for position resolution measurements, discuss the problems and solutions encountered in the past experiment, and report the projected position resolutions of about 300 nm at best.