Laser spectroscopy of metastable states in the [Formula Presented] cascade of antiprotonic [Formula Presented]

F. J. Hartmann, B. Ketzer, C. Maierl, R. Pohl, T. von Egidy, R. S. Hayano, M. Hori, T. Ishikawa, H. Tamura, H. A. Torii, M. Kumakura, N. Morita, I. Sugai, D. Horváth, J. Eades, E. Widmann, T. Yamazaki

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


The pressure dependence of the metastable-state lifetimes in antiprotonic [Formula Presented] atoms [Formula Presented] was studied using the recently observed laser resonance transition [Formula Presented] in the [Formula Presented] cascade. To this end antiprotons from the Low Energy Antiproton Ring (LEAR) at CERN were extracted in approximately 200-ns-long bunches with about [Formula Presented] per bunch and stopped in a [Formula Presented] gas target. Time spectra of delayed annihilation products were taken with the help of a Čerenkov counter with a gated photomultiplier. Under our experimental conditions, [Formula Presented] and [Formula Presented] the lowest metastable level [Formula Presented] was found to be much shorter lived than the corresponding state (37,34) in the [Formula Presented] cascade of [Formula Presented] It was strongly quenched at pressures above 500 mbars, whereas the higher states in the cascade remained nearly unaffected. This enabled us to investigate the [Formula Presented] transition by resonant laser deexcitation. Its wavelength was found to be [Formula Presented] only 6 ppm lower than the theoretical value given by Korobov and Bakalov [Phys. Rev. Lett. 79, 3379 1997)] after including relativistic corrections.

Original languageEnglish
Pages (from-to)3604-3610
Number of pages7
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number5
Publication statusPublished - 1998


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