Positron Annihilation Lifetime Spectroscopy (PALS) is one of the most effective material analysis techniques at detecting sub-nanometer defects in materials. Current conventional PALS facilities use positron beams of low keV energies and long durations, resulting in poor penetration depth and durations similar to the annihilation lifetime (~150ps), therefore giving poor resolution. By using...
As a purely leptonic system, precise measurement of the properties of positronium (Ps) offers a unique avenue for testing bound-state QED theory and physics beyond the standard model if experimental uncertainties can match or exceed those of theoretical results. The decay rate of the triplet ground-state (o-Ps) due to annihilation has been determined to an experimental uncertainty of 100 ppm...
Precision spectroscopy of the positronium (Ps) $n = 2$ fine structure intervals has been performed several times to test bound state QED [1]. All previous measurements have used microwave waveguides with a fixed polarisation (e.g. [2,3,4]), and the effect of polarisation on these transitions has not been explored. The polarisation can change the subset of transitions driven by the radiation,...
Metastable antiprotonic helium is a neutral three-body atom [1-6] that contains a helium nucleus, an electron occupying the 1s state, and an antiproton in a Rydberg state of large principal (n≈38) and orbital angular momentum (l=n-1) quantum numbers. Whereas spectroscopy of antihydrogen atoms probes the interaction between an antihadron and antilepton, the antiprotonic helium atom is a...
