A Pulsed Muon Source Based on a High-Repetition-Rate Electron Accelerator

TL;DR

This paper explores using a high-repetition-rate electron accelerator at Shanghai SHINE to generate pulsed muon beams, potentially enhancing precision in muon experiments beyond current low-duty-cycle sources.

Contribution

It proposes a novel muon source driven by a 1 MHz electron beam at SHINE, supported by Monte Carlo simulations estimating muon yield for advanced experiments.

Findings

Estimated muon yield of ~10^3 muons per bunch.

Potential to improve muon experiment precision and scope.

Feasibility demonstrated through Geant4 simulations.

Abstract

Muons have established a unique and pivotal role in both fundamental physics and applied sciences. Given that a typical muon experiment spans roughly ten muon lifetimes, the optimal muon source should operate at around 50\,kHz in pulsed mode. However, existing muon facilities operate in either the 25-50\,Hz pulsed mode or continuous beam (DC) mode, which results in low-duty cycles for various muon experiments. As a result, precision muon physics with continuous muon beam has been limited by statistical uncertainty. In this study, we investigate the potential of a high-repetition-rate pulsed electron beam at the Shanghai SHINE facility to serve as a muon source driver. SHINE houses an 8-GeV CW superconducting RF linac, with a 1\,MHz bunch rate and 100\,pC bunch charge. Following X-ray production, the electron beam is deflected downstream of the undulators and absorbed in a beam dump. Using Geant4 Monte Carlo simulations, we estimated the yield of the muon beam to be approximately $10^{3}\mu^{\pm}$/bunch. This type of muon beam could be instrumental in a broad range of muon experiments, including muon lifetime measurement, a search for muonium to anti-muonium conversion, and the muon spin spectroscopy.