High-Resolution X-Ray Spectroscopy of Muonic Atoms with Superconducting Transition-Edge Sensor Microcalorimeters

Abstract

Using an intense slow muon beam at J-PARC and superconducting X-ray microcalorimeters, we performed high-precision X-ray spectroscopy of muonic and electronic X-rays emitted from muonic atoms. A proof-of-principle experiment for a strong-field QED test with muonic atoms has been achieved by precisely measuring muonic X-rays emitted by muonic Ne. High-resolution measurements of electronic X-rays have also allowed us to observe muonic Ar with 1–3 bound electrons and to reveal the femtosecond dynamics in the formation process of muonic Fe.