Development of a low-energy, high-brightness $\mu^+$ beam line

TL;DR

This paper presents the development of a novel muon beam line that significantly compresses phase space, achieving high brightness and low energy, through a multi-stage process involving transverse and longitudinal compression in a helium gas target.

Contribution

It introduces the first observation of transverse phase space compression and demonstrates efficient longitudinal compression within a short timescale, advancing muon beam technology.

Findings

Transverse compression observed for the first time.

Longitudinal compression occurs within 2.5 microseconds.

Achieved phase space compression by 10 orders of magnitude with 0.1% efficiency.

Abstract

We are developing a beam line which compresses the phase space of a standard surface $\mu^+$ beam by 10 orders of magnitude with an efficiency of $10^{-3}$. Phase space compression occurs in a He gas target and consists of three consecutive stages: Transverse (perpendicular to the beam axis) compression, longitudinal compression and re-extraction into vacuum. Transverse compression was observed for the first time and longitudinal compression has been measured to occur within 2.5 $\mu$s with high efficiency.