International Conference on Exotic Atoms and Related Topics - EXA2017

Experiments using positronium (Ps) atoms are often complicated by low numbers of atoms, and the fact that they self-annihilate in around 142 ns (for the “long-lived” states). The latter problem can be avoided if the atoms are optically excited to long-lived Rydberg states, which don’t annihilate to any significant degree. This has become much easier to accomplish in recent years using positron bugger gas trapping technology [1], allowing the efficient production of Rydberg Ps atoms [2]. As well as increasing their lifetime, exciting Ps atoms to Rydberg levels also makes it possible to manipulate them using electric fields because of their large dipole moments [3]. Here I will report the first demonstration of such manipulation of Ps atoms [4], and discuss future applications, including precision spectroscopy of Rydberg Ps levels. If it can be performed with sufficiently high precision, this may be of relevance to the proton radius problem [5], since Ps is composed only of leptons. References [1] J.R. Danielson et al., Rev. Mod. Phys. 87, 247 (2015). [2] D. B. Cassidy et al., Phys. Rev. Lett. 108, 043401 (2012). [3] T.E. Wall, et al., Phys. Rev. Lett. 114, 173001 (2015). [4] A. Deller, et al., Phys. Rev. Lett. 117, 073202 (2016). [5] R. Pohl et al., Ann. Rev. Nucl. Part. Sci. 63 175 (2013).