Speaker
Description
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 [1], two orders of magnitude larger than current theory (2.7 ppm) [2]. Previous experimental methods [1, 3, 4] have required detailed models of the interaction of Ps with matter and fields, that ultimately limit the possible precision. Here we investigate an alternative technique, wherein an energetic o-Ps beam produced via positron-gas collisions in a gas cell [5, 6] is allowed to decay in free-space. The surviving fraction is determined for various flight times using an adjustable micro-channel plate detector. Initial results are presented and improvements required to achieve competitive precision are discussed.
References:
[1] Y. Kataoka, S. Asai, and T. Kobayashi, Phys. Lett. B, 671 219 (2009)
[2] G. S. Adkins, D. B. Cassidy and J. Perez-Rios, Phys. Rep., 975 1 (2022)
[3] R. S. Vallery, P. W. Zitzewitz, D. W. Gidley, Phys. Rev. Lett. 90 203403 (2003)
[4] S. Asai, O. Jinnouchi, T. Kobayashi, Int. J. Mod. Phys. A 19 3927 (2004)
[5] A. Ozen, A. J. Garner, G. Laricchia, Nucl. Instrum. and Meth. in Phys. Res. B 171 172 (2000)
[6] D. M. Newson, T. J. Babij, D. B. Cassidy, Rev. Sci. Instrum., 94 083201 (2023)
