A diagnostic system of 5.7 keV muon beam for muon accelerator

Realization of a low-emittance muon beam through the acceleration of keV-scale muons requires the injection of a suitably matched beam into an accelerator, since beam mismatch can lead to emittance growth and reduced acceleration efficiency. In one such scheme, muons are first thermalized to room temperature and then injected into a linear accelerator. Non-destructive diagnostics are challenging because of the low energy and low intensity. We developed a compact low-energy muon diagnostic system compatible with the accelerator under construction at J-PARC. The system is designed to evaluate beam conditions required for precise tuning prior to acceleration. Commissioning with low-energy muon sources shows the system's capability to identify low-energy muon signals and measure beam profiles.