Fast readout algorithm for cylindrical beam position monitors providing good accuracy for particle bunches with large offsets

TL;DR

This paper introduces a fast, accurate algorithm for cylindrical beam position monitors that works well even with large beam offsets, and demonstrates its effectiveness through simulations, corrections, and real data testing.

Contribution

A simple, analytically correct algorithm for BPM signal processing is developed and validated for both ideal and realistic cylindrical BPMs, including FPGA implementation.

Findings

Small deviations in position calculation with ideal BPMs

Correction terms improve accuracy further

Effective FPGA-based readout implementation

Abstract

A simple, analytically correct algorithm is developed for calculating pencil beam coordinates using the signals from an ideal cylindrical particle beam position monitor (BPM) with four pickup electrodes (PUEs) of infinitesimal widths. The algorithm is then applied to simulations of realistic BPMs with finite width PUEs. Surprisingly small deviations are found. Simple empirically determined correction terms reduce the deviations even further. The algorithm is then used to study the impact of beam-size upon the precision of BPMs in the non-linear region. As an example of the data acquisition speed advantage, a FPGA-based BPM readout implementation of the new algorithm has been developed and characterized. Finally,the algorithm is tested with BPM data from the Cornell Preinjector.