Observation of kaonic hydrogen atom X-ray

S. N. Nakamura, K. Bartlett, G. A. Beer, G. R. Gill, R. S. Hayano, T. M. Ito, M. Iwasaki, L. Lee, G. Mason, A. Olin, H. Outa, M. Salomon, R. Seki, T. Taniguchi, T. P. Terada, G. Trayling, Y. Yamashita, S. Yen

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


We successfully observed clear K-series kaonic hydrogen X-rays for the first time taking advantage of two charged pions tagging technique and a gaseous hydrogen target. The strong-interaction energy shift and width of 1s state of K-p atom were determined to be ΔE1s = -323 ± 63 (statistical) ± 11 (systematic) eV and Γ1s = 407 ± 208 ± 100 eV. Our result means that the K-p strong interaction near threshold is repulsive and the long-standing kaonic hydrogen puzzle is solved.

Original languageEnglish
Pages (from-to)45-51
Number of pages7
JournalHyperfine Interactions
Issue number1-4
Publication statusPublished - 1999
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Nuclear and High Energy Physics
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry


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