Deexcitation Dynamics of Muonic Atoms Revealed by High-Precision Spectroscopy of Electronic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>K</mml:mi></mml:math> X Rays
T. Okumura, T. Azuma, D. A. Bennett, Peter Caradonna, I. Chiu, W. B. Doriese, M. S. Durkin, Joseph W. Fowler, J. Gard, T. Hashimoto, R. Hayakawa, G. C. Hilton, Yuto Ichinohe, P. Indelicato, T. Isobe, S. Kanda, Daiji Kato, M. Katsuragawa, N. Kawamura, Yasushi Kino, M. K. Kubo, Kairi Mine, Yasuhiro Miyake, Kelsey M. Morgan, Kazuhiko Ninomiya, Hirofumi Noda, G. C. O’Neil, S. Okada, Kenichi Okutsu, Takahito Osawa, N. Paul, C. D. Reintsema, D. R. Schmidt, K. Shimomura, P. Strasser, H. Suda, Daniel S. Swetz, Tadayuki Takahashi, Shin’ichiro Takeda, Soshi Takeshita, M. Tampo, H. Tatsuno, Xiao‐Min Tong, Y. Ueno, Joel N. Ullom, Shin Watanabe, S. Yamada
Abstract
We observed electronic K x rays emitted from muonic iron atoms using superconducting transition-edge sensor microcalorimeters. The energy resolution of 5.2 eV in FWHM allowed us to observe the asymmetric broad profile of the electronic characteristic Kα and Kβ x rays together with the hypersatellite K^{h}α x rays around 6 keV. This signature reflects the time-dependent screening of the nuclear charge by the negative muon and the L-shell electrons, accompanied by electron side feeding. Assisted by a simulation, these data clearly reveal the electronic K- and L-shell hole production and their temporal evolution on the 10-20 fs scale during the muon cascade process.