Berlin 2001 – wissenschaftliches Programm
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A: Atomphysik
A 10: Posters Wednesday (Cooling and Trapping, Electron Scattering and Recombination)
A 10.28: Poster
Mittwoch, 4. April 2001, 12:30–15:00, AT3
Towards a new Measurement of the Decay Rate of the Positronium Negative Ion — •K. Degreif1, F. Fleischer1, G. Gwinner1, R. Ley2, F. Plenge1, and D. Schwalm1 — 1MPI für Kernphysik, 69029 Heidelberg — 2Institut für Physik, 55099 Mainz
Consisting of two
electrons and a positron, the positronium
negative ion (Ps−) represents the simplest three-body-system with a
bound
state. Being free from perturbations due to strong interactions the system
provides interesting opportunities to test our understanding of the
three-body
problem and quantum electrodynamics. Previous
experiments have so far only proved the existence of Ps− [1] and
determined
the decay rate with 4% accuracy [2]. To
allow for a test of radiative corrections and bound-state
contributions to the decay rate an increase in precision of at least
one order of magnitude is necessary. Of particular interest is
also the measurement of the 3γ/2γ-branching ratio because of
its
relevance to the ortho-Ps lifetime and the photoionization cross section of
Ps−. An experiment has been built up at the MPI für Kernphysik to
investigate the decay rate and other properties of Ps− in more
detail. The set-up and first measurements concerning the production rate
of
Ps− will be discussed.
[1] A.P. Mills, Jr., Phys. Rev. Lett. 46, 717(1981)
[2] A.P. Mills, Jr., Phys. Rev. Lett. 50, 671(1983)