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 (${\mu }^{+}$) and two electrons, are generated from ${\mu }^{+}$'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.