Negative muon coulomb capture on nitrogen oxide molecules

Ninomiya, Kazuhiko; Ito, Takashi   ; Higemoto, Wataru  ; Kita, Makoto*; Shinohara, Atsushi*; Nagatomo, Takashi*; Kubo, Kenya*; Strasser, P.*; Kawamura, Naritoshi*; Shimomura, Koichiro*; Miyake, Yasuhiro*; Miura, Taichi*

A muonic atom is an atomic system that contains one negatively charged muon (muon is one of elementally particles) instead of an electron. When a muon is injected in material, the muon is slowing down by collisions with atomic electrons, and then low energy muon is captured on the coulomb field of a nucleus. As a result, the muon forms an atomic orbit around the nucleus, that is, a muonic atom is formed. It is considered that a muon capture phenomenon proceeds through muon collision and replacement with loosely binding electron, however the intrinsic mechanism of muon capture have not been investigated yet. In this study, we examine the formation processes of muonic atoms for nitrogen oxide samples (NO, NO and NO) by measuring muon characteristic X-rays (muonic X-rays) emitted after formation of muonic atoms.