Speaker
Description
Positronium (Ps) decay rate measurements can be used to test QED theory [1], and in the search for new physics. Previous experiments have measured the annihilation decay rates of the ground states [2,3], and the excited $2\,^3\mathrm{S}_1$ state [4] of Ps. We report a measurement of the fluorescence decay rate of Ps atoms in the $2\,^3\mathrm{P}_J$ level using a new technique. By applying an electric field to metastable $2\,^3\mathrm{S}_1$ Ps atoms, we produced Stark-mixed states with both $2\,^3\mathrm{S}_1$ and $2\,^3\mathrm{P}_J$ components, and controlled their relative populations by varying the strength of the field. A larger electric field was subsequently applied to induce rapid quenching, and annihilation, of the mixed states. The number of quenched atoms across various mixing field strengths was measured, and these measurements, along with Monte Carlo simulations, were used to determine the decay rate of the $2\,^3\mathrm{P}_J$ state.
[1] S. G Karshenboim, Precision study of positronium: Testing bound state QED theory, Int. J. Mod. Phys. A 19, 3879 (2004).
[2] Al-Ramadhan A. H. and Gidley D. W., New precision measurement of the decay rate of singlet positronium, Phys. Rev. Lett., 72 1632 (1994).
[3] Nico J. S., Gidley D. W., Rich A. and Zitzewitz, Precision measurement of the orthopositronium decay rate using the vacuum technique, P. W., Phys. Rev. Lett., 65, 1344 (1990).
[4] R. E. Sheldon et al., Measurement of the annihilation decay rate of $2\,^3\textrm{S}_1$ positronium, EPL 132 13001 (2020).
