First muon acceleration using a radio-frequency accelerator

Abstract

Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu^{-}), which are bound states of positive muons (μ^{+}) and two electrons, are generated from μ^{+}’s through the electron capture process in an aluminum degrader. The generated Mu^{-}’s are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ). In the RFQ, the Mu^{-}’s are accelerated to 89 keV. The accelerated Mu^{-}’s are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.