New PRL on positronium interactions with atoms
Last updated June 12, 2018 by Andrew Brown
Positronium (Ps) is a light ‘atom’ that consists of an electron and its antiparticle (positron). This simplest matter-antimatter system is of fundamental importance for testing quantum electrodynamics, and is widely used in condensed matter for probing voids and free space, and as a precursor for making antihydrogen at CERN. In spite of its importance, the interaction and collisions of low-energy Ps with normal matter, e.g., atoms or molecules, are not fully understood. Theoretically, the problem is made challenging by the effect of structure of both the projectile and target.
In their latest paper Phys. Rev. Lett. 120, 183402 Dermot Green, Andrew Swann and Gleb Gribakin from the CTAMOP Antimatter and Atomic Many-body Theory Group present a new first-principles theoretical approach to describe Ps interactions with noble-gas atoms, which takes account of the distortion of the Ps and the atom during their interaction. Notably, they demonstrate that their approach gives the best agreement with experiment for the pick-off annihilation rate (where the positron from positronium annihilates with one of the atomic electrons), resolving a long-standing discrepancy between theory and experiment.
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