Measurement of the annihilation decay rate of 2 3S1 positronium

R. E. Sheldon; T. J. Babij; B. A. Devlin-Hill; L. Gurung; D. B. Cassidy

doi:10.1209/0295-5075/132/13001

All issues

Volume 132 / No 1 (October 2020)

EPL, 132 1 (2020) 13001

Abstract

Issue		EPL Volume 132, Number 1, October 2020


Article Number		13001
Number of page(s)		7
Section		Atomic, Molecular and Optical Physics
DOI		https://doi.org/10.1209/0295-5075/132/13001
Published online		02 November 2020

EPL, 132 (2020) 13001

Measurement of the annihilation decay rate of 2 ³S₁ positronium

R. E. Sheldon, T. J. Babij, B. A. Devlin-Hill, L. Gurung and D. B. Cassidy

Department of Physics and Astronomy, University College London - Gower Street, London, WC1E 6BT UK

Received: 24 July 2020
Accepted: 12 October 2020

Abstract

We report a measurement of the annihilation decay rate of ${2\,}^{3}\mathrm{S}_1$ positronium (Ps) atoms, $\Gamma_{\mathrm{exp}}({2\,}^{3}\mathrm{S}_1)$ . Ground state atoms optically excited to radiatively metastable ${2\,}^{3}\mathrm{S}_1$ states were quenched via Stark mixing by the application of a time-delayed electric field. Rapid radiative decay of the Stark mixed states to the ground state, followed by self-annihilation, was observed via the annihilation radiation time spectrum, and used to determine the number of excited state atoms remaining at different times, and hence the decay rate. We obtain $\Gamma_{\mathrm{exp}}({2\,}^{3}\mathrm{S}_1) = 843\pm72\ \text{kHz}$ , in broad agreement with the Zeeman-shifted theoretical value of $890\ \text{kHz}$ .

PACS: 36.10.Dr – Positronium / 31.50.Df – Potential energy surfaces for excited electronic states / 32.70.Cs – Oscillator strengths, lifetimes, transition moments

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