Microwave spectroscopy measurements of the hyperfine structure in antiprotonic 3He

Susanne Friedreich, Daniel Barna, Fritz Caspers, Andreas Dax, Ryugo Hayano, Masaki Hori, Dezso Horváth, Bertalan Juhász, Takumi Kobayashi, Oswald Massiczek, Anna Sótér, Koichi Todoroki, Eberhard Widmann, Johann Zmeskal

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We shall present here the first experimental results for microwave spectroscopy of the hyperfine structure of antiprotonic He-3 and a comparison to numerical simulations of the measurement. Due to the helium nuclear spin, antiprotonic He-3 has a more complex hyperfine structure than antiprotonic He-4 which has already been studied before. Thus a comparison between theoretical calculations and the experimental results will provide a more stringent test of the three-body quantum electrodynamics (QED) theory. The comparison of measured data to simulations allows to investigate the collisional processes between the helium atoms of the target medium and the antiprotonic helium atomcules. The collision rates can not be calculated exactly, but estimated by comparison of numeric simulations with the experimental results. Two out of four super-super-hyperfine (SSHF) transition lines of the (n, L) = (36, 34) state were observed. The measured frequencies of the individual transitions are 11. 12559(14) GHz and 11. 15839(18) GHz, less than 1 MHz higher than the current theoretical values, but still within their estimated errors. The frequency difference between the two lines also agrees with theoretical calculations.

Original languageEnglish
Pages (from-to)167-177
Number of pages11
JournalHyperfine Interactions
Issue number1-3
Publication statusPublished - Dec 1 2012



  • Antiproton
  • Antiprotonic helium
  • Hyperfine structure
  • Laser
  • Microwave
  • Spectroscopy
  • Three-body quantum electrodynamics

ASJC Scopus subject areas

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

Cite this

Friedreich, S., Barna, D., Caspers, F., Dax, A., Hayano, R., Hori, M., Horváth, D., Juhász, B., Kobayashi, T., Massiczek, O., Sótér, A., Todoroki, K., Widmann, E., & Zmeskal, J. (2012). Microwave spectroscopy measurements of the hyperfine structure in antiprotonic 3He. Hyperfine Interactions, 212(1-3), 167-177. https://doi.org/10.1007/s10751-012-0639-y