Spectroscopy of excited state positronium |
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Authors: | Richard Ley D Hagena D Weil G Werth W Arnold H Schneider |
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Institution: | (1) Institut für Physik, Johannes Gutenberg-Universität Mainz, D-5099 Mainz, Germany;(2) Strahlenzentrum, Justus Liebig-Universität Giessen, D-35392 Giessen, Germany |
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Abstract: | Electric dipole transitions in the microwave range have been induced between the fine-structure levels of positronium in the excited staten=2. As an indication of the transitions, we used the increase in Lyman- radiation when the metastable 23S1-level is depopulated. The results for the transitions 23S123P0,1,2 are
0=18499.65±1.20±4.00 MHz,
1=13012.42 ±0.65±1.54 MHz and
2=8624.38±0.54±1.40 MHz. The first error is statistical and the second systematic. The precision of the present measurement has improved by a factor of 3, compared to previous data. Recent bound state QED-calculations have been extended to the orderR
t8
4ln
–1. The not yet completely calculated orderR
t8
4 is estimated to contribute less than 1 MHz. Our experimental results are in good agreement with theory. By applying a weak magnetic field, we were able to observe the transition 23S121P1 which is strictly forbidden byC-invariance in zero field. Our result, corrected for Zeeman- and motional Starkeffect, is
3=11180.0±5.0±4.0 MHz. An upper limit for theC-violating matrix element of
MHz could be deduced. Our experiment used moderated slow positrons from the bremsstrahlung and pair production of a pulsed electron linear accelerator (TEPOS facility at the university of Giessen). |
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Keywords: | |
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