Efficient $2^{3}S$ positronium production by stimulated decay from the $3^{3}P$ level

Abstract

We investigate experimentally the possibility of enhancing the production of $2^{3}S$ positronium atoms by driving the $1^{3}S$-$3^{3}P$ and $3^{3}P$-$2^{3}S$ transitions, overcoming the natural branching ratio limitation of spontaneous decay from $3^{3}P$ to $2^{3}S$. The decay of $3^{3}P$ positronium atoms towards the $2^{3}S$ level has been effciently stimulated by a 1312.2nm broadband IR laser pulse. The dependence of the stimulating transition efficiency on the intensity of the IR pulse has been measured to find the optimal enhancement conditions. A maximum relative increase of $\times (3.1\pm 1.0)$ in the $2^{3}S$ production efficiency, with respect to the case where only spontaneous decay is present, was obtained.

6 pages, 4 figures