線型加速器によるミューオン加速

抄録

At the J-PARC muon science facility, a muon linac for a muon g-2/EDM experiment is being developed. In this experiment, Ultra-Slow Muons (USMs), which are generated by resonantly ionizing the thermal muonium evaporated from a silica aerogel, will be accelerated to 212 MeV. The momentum spread of the accelerated muon beam is 0.1%, and the normalized transverse emittance is approximately 1.5π mm mrad. Proof of the slow muon acceleration scheme is an essential step toward realizing the world’s first muon linac. In October 2017, we succeeded in accelerating slow negative muoniums generated using a simpler muonium source, even though they are not USMs. 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. Generated Mu⁻’s are accelerated to 89 keV by a radio frequency quadrupole linac. In this paper, the present design of the muon linac for the g-2/EDM experiment and the result of the world first demonstration of the muon acceleration are described.