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 (${\mathrm{Mu}}^{\ensuremath{-}}$), which are bound states of positive muons (${\ensuremath{\mu}}^{+}$) and two electrons, are generated from ${\ensuremath{\mu}}^{+}$'s through the electron capture process in an aluminum degrader. The generated ${\mathrm{Mu}}^{\ensuremath{-}}$'s are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ). In the RFQ, the ${\mathrm{Mu}}^{\ensuremath{-}}$'s are accelerated to 89 keV. The accelerated ${\mathrm{Mu}}^{\ensuremath{-}}$'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.