Pressure dependence of muonic X-ray structures for dinitrogen oxide gas samples

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

A muonic atom is an atomic system that has one negatively charged muon instead of an electron. There are many studies related to the formation process of muonic atom by measuring muon characteristic X-rays. It is known that muon characteristic X-ray intensities are influenced by the density of the sample itself. However, most of previous studies did not consider this effect. In this study, we measured muon characteristic X-rays for dinitrogen mono-oxide with 0.1-1.0 atm. The same muonic X-ray intensities were obtained below 0.2 atm condition. This result means the density effect is neglectable below 0.2 atm for dinitrogen mono-oxide gas.