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Phys. Rev. A 66, 022504 (2002) [6 pages]

Anomalies in the decay rates of antiprotonic helium-atom states

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H. Yamaguchi, T. Ishikawa, J. Sakaguchi, and E. Widmann
Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

J. Eades, R. S. Hayano, and M. Hori
CERN, CH-1211 Geneva 23, Switzerland

H. A. Torii
Institute of Physics, University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan

B. Juhász
Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, Hungary

D. Horváth
KFKI Research Institute For Particle and Nuclear Physics, H-1525 Budapest, Hungary

T. Yamazaki
RI Beam Science Laboratory, RIKEN, Wako, Saitama 351-0198, Japan

Received 13 February 2002; published 15 August 2002

Six resonance transitions of the antiprotonic helium atom in helium gas at densities of 3×1020–3×1021 cm-3 were studied at the antiproton decelerator (AD) of CERN. The decay rates of the daughter states of these transitions were determined either from the time distributions of the resonance spikes or from the widths of the resonance lines. Whereas most of the observed decay rates agree with theoretical calculations of Auger rates, two states, (n,l)=(37,33) and (32,31), were found to have decay rates two orders of magnitude larger than predicted by these calculations. The effect of coupling with near-lying electron-excited states is considered to be the reason for the anomaly of the (37, 33) state, as pointed out by Kartavtsev et al. [Phys. Rev. A 61, 062507 (2000)].


©2002 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevA.66.022504
DOI: 10.1103/PhysRevA.66.022504
PACS: 36.10.-k, 32.80.Dz

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