Positronium formation for positron scattering from metastable hydrogen
Lin Lin, Wang Hong-Nian, Jiao Li-Guang
       

(color online) Total Ps formation cross sections for positron impact on H(2s) and H(1s). Also shown in the inset are the comparison of the Ps formation cross sections of H(1s) with other theoretical calculations and experimental measurements. For details of the references, see Fig. 7 of Ref. [18].