Fermilab Booster Beam Emittances from Quadrupole Modes Measured by BPMs

TL;DR

This paper presents an improved method for measuring beam emittances using multiple BPMs and advanced analysis, resulting in more accurate and realistic measurements compared to traditional ion profile monitors.

Contribution

The paper introduces a novel approach combining multiple BPMs with enhanced mathematical analysis to improve emittance measurement accuracy.

Findings

BPM-derived emittances are more realistic than IPM measurements.

The new method significantly improves signal-to-noise ratio.

The approach simplifies tuning requirements for emittance extraction.

Abstract

The measurement of beam emittances by extracting the quadrupole mode signal from a 4 plate beam position monitor (BPM) was published at least 40 years ago. Unfortunately, in practice, this method suffers from poor signal to noise ratio and requires a lot of tuning to extract out the emittances. In this paper, an improved method where multiple BPMs are used together with better mathematical analysis is described. The BPM derived emittances are then compared with those measured by the Ion Profile Monitor (IPM). Surprisingly, the BPM measured emittances behave very well and are more realistic than those measured by the IPM.