Benchmarking the Use of BPM Quadrupole Moments to Measure Emittance

TL;DR

This paper evaluates the use of BPM quadrupole moments as a non-intercepting method to measure transverse emittance in the Fermilab Booster, demonstrating comparable results to existing techniques.

Contribution

It introduces a benchmarking approach for using BPM quadrupole moments to measure emittance, showing its effectiveness and potential as a supplementary method.

Findings

BPM quadrupole moments can reliably infer emittance.

Derived emittance measurements align with IPM and Multiwire data.

The method offers a non-intercepting alternative for emittance monitoring.

Abstract

For the PIP-II program, transverse emittance in the Fermilab Booster must remain well controlled at higher bunch intensities. 4-plate beam position monitors (BPMs) have a small but measurable quadrupole moment, making it possible to infer transverse emittance. By compositing many BPMs together, it becomes possible to improve the quality of the quadrupole signal. The Fermilab Booster BPM system has been used to measure these quadrupole moments in the past year and derive emittances from them. Recent benchmarks show that the derived BPM emittances show similar emittance evolution and value to IPM and Multiwire data. This approach can both supplement and complement existing non-intercepting emittance monitors in accelerators.