Excited State Positronium.

Abstract

Experimental tests in excited state positronium (Ps*) are considered and reported. These include formation of Ps*, tests of QED in it, and tests of discrete symmetries C, P, and T. A survey of Ps* formation on various polycrystalline metals is reported and measurements of three fine structure splittings in Ps* are presented: The $2\sp3S\sb1 \rightarrow 2\sp3P\sb1$ and $2\sp3S\sb1\rightarrow 2\sp3P\sb0$ transition frequencies ($\nu\sb1$ and $\nu\sb0$, respectively) in positronium have been measured and an improved measurement of the $2\sp3S\sb1 \rightarrow 2\sp3P\sb2$ transition frequency ($\nu\sb2$) has been made. The results $\nu\sb2 = 8619.6 \pm 2.7 \pm 0.9$ MHz, $\nu\sb1 = 13001.3 \pm 3.9 \pm 0.9$ MHz, and $\nu\sb0 = 18504.1 \pm 10.0 \pm 1.7$ MHz are in good agreement with the predictions of bound state quantum electrodynamics which are to order $\alpha\sp3Rydberg$; $\nu\sb0(\alpha\sp3) = 18496.1$ MHz, $\nu\sb1(\alpha\sp3) = 13010.9$ MHz, and $\nu\sb2(\alpha\sp3) = 8625.2$ MHz. Experiments to test discrete symmetries are considered in detail. This work was funded by NSF grant PHY-8403817.