Bonn 2010 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 54: Fundamentale Symmetrien II
HK 54.8: Talk
Thursday, March 18, 2010, 18:45–19:00, HG V
A New Decay Rate Measurement of the Negative Positronium Ion† — •Stefan Alexander Gärtner1, Hubert Ceeh2, Frank Fleischer3, Christoph Hugenschmidt2, Klaus Schreckenbach2, Dirk Schwalm4, and Peter Thirolf1 — 1Ludwig-Maximilians-Universität München, Garching, Germany — 2Technische Universität München and FRM II, Garching, Germany — 3University of Washington, Seattle, USA — 4Max-Planck-Institut für Kernphysik, Heidelberg, Germany
The results of a new decay rate measurement of the Ps− ion (e+e−e−) at the NEPOMUC high flux positron source (≈ 4·107 remoderated positrons per second) at the FRM II reactor in Garching are shown. The setup utilizes ≈ 5 nm thin Diamond Like Carbon (DLC) foils for the Ps− production as well as for stripping off the electrons, which takes place immediately after the acceleration across a variable length gap. This technique has been employed by a previous experiment [1] in Heidelberg using a 22Na source resulting in the most recent decay rate value of Γ = 2.089(15) ns−1. Higher statistics led to new insight into systematic errors, which could be improved by an electrically field-free decay gap, thus yielding an error of ≈ 0.2 %, which allows to test QED [2] for this fundamental three-body system. In a further step the photodetachment cross section of Ps− will be measured at the two energies provided by the fundamental and second harmonic mode of a high power Nd:YAG laser for the first time. [1] F. Fleischer et al., Phys. Rev. Lett. 96, 063401 (2006). [2] M. Puchalski et al., Phys. Rev. Lett. 99, 203401 (2007). †Supported by DFG under contract HA1101/13-1.