LLRF system for the Fermilab Muon g-2 and Mu2e projects

TL;DR

This paper describes the design and initial testing of a specialized Low-Level Radio Frequency (LLRF) system for Fermilab's Muon g-2 and Mu2e experiments, addressing complex timing and frequency challenges.

Contribution

It introduces a novel LLRF system implementation using SOC FPGA technology to meet the unique timing and frequency requirements of both experiments.

Findings

Successful initial beam commissioning tests for Muon g-2

Achieved phase alignment within specifications for beam transfer

Demonstrated effective integration with existing LLRF infrastructure

Abstract

The Mu2e experiment measures the conversion rate of muons into electrons and the Muon g-2 experiment measures the muon magnetic moment. Both experiments require 53 MHz batches of 8 GeV protons to be re-bunched into 150 ns, 2.5 MHz pulses for extraction to the g-2 target for Muon g-2 and to a delivery ring with a single RF cavity running at 2.36 MHz for Mu2e. The LLRF system for both experiments is implemented in a SOC FPGA board integrated into the existing 53 MHz LLRF system in a VXI crate. The tight timing requirements, the large frequency difference and the non-harmonic relationship between the two RF systems provide unique challenges to the LLRF system design to achieve the required phase alignment specifications for beam formation, transfers and beam extinction between pulses. The new LLRF system design for both projects is described and the results of the initial beam commissioning tests for the Muon g-2 experiment are presented.