Ultra Slow Muon Microscopy for Nano-science

Abstract

The "surface" muon beam which has been used for the studies of condensed matter physics or chemistry is conventionally obtained from the decay of positive pions (π+) stopped near the surface of the pion production target in the proton beam line and has large energy broadening with an implantation depth of 0.1 to 1 mm. Despite the name of "surface" muon, it is used as a probe of bulk phenomena rather than surface phenomena. In these two decades, the new method to generate ultra-slow muon beam with energy 0.2 eV has been developed and successfully obtained by KEK and RIKEN group. When the production of intense ultra-slow muon source will be realized, the use of its short-range penetration depth will allow muon science to be expanded towards a variety of new nano-scientific fields, which we call "Ultra Slow Muon Microscope" such as, 1) Surface/boundary magnetism utilizing its spin polarization and unique time-window. 2) Surface chemistry, utilizing a feature of a light isotope of hydrogen; such as catalysis reactions. 3) Muon Microscopy, utilizing a feature of micron meter beam size, when ultra slow muon is accelerated. 4) Precise atomic physics testing QED, since Mu is the simplest lepton pair consisting μ+ and e−. 5) Ion sources for- "g-2" experiment, and towards μ+ μ− collider experiments in high-energy physics.Int this paper, the latest status of the intense low-emittance ultra slow muon source and its scientific prospects will be reported.