High-resolution pionic-atom x-ray spectroscopy was performed with an x-ray spectrometer based on a 240-pixel array of superconducting transition-edge-sensor (TES) microcalorimeters at the piM1 beam line of the Paul Scherrer Institute. X-rays emitted by pionic carbon via the 4f->3d transition and the parallel 4d->3p transition were observed with a full-width-at-half-maximum energy resolution of 6.8 eV at 6.4 keV. Measured x-ray energies are consistent with calculated electromagnetic values which considered the strong-interaction effect assessed via the Seki-Masutani potential for the 3p energy level, and favor the electronic population of two filled 1s electrons in the K-shell. Absolute energy calibration with an uncertainty of 0.1 eV was demonstrated under a high-rate hadron beam condition of 1.45 MHz. This is the first application of a TES spectrometer to hadronic-atom x-ray spectroscopy and is an important milestone towards next-generation high-resolution kaonic-atom x-ray spectroscopy.
@article{arxiv.1608.05436,
title = {First application of superconducting transition-edge-sensor microcalorimeters to hadronic-atom x-ray spectroscopy},
author = {S. Okada and D. A. Bennett and C. Curceanu and W. B. Doriese and J. W. Fowler and J. Gard and F. P. Gustafsson and T. Hashimoto and R. S. Hayano and S. Hirenzaki and J. P. Hays-Wehle and G. C. Hilton and N. Ikeno and M. Iliescu and S. Ishimoto and K. Itahashi and M. Iwasaki and T. Koike and K. Kuwabara and Y. Ma and J. Marton and H. Noda and G. C. O'Neil and H. Outa and C. D. Reintsema and M. Sato and D. R. Schmidt and H. Shi and K. Suzuki and T. Suzuki and D. S. Swetz and H. Tatsuno and J. Uhlig and J. N. Ullom and E. Widmann and S. Yamada and J. Yamagata-Sekihara and J. Zmeskal},
journal= {arXiv preprint arXiv:1608.05436},
year = {2016}
}