Positronium in space: Proposal for detection

We propose to observe the strongest recombination lines of positronium atom s L-alpha (2431 Angstrom), H-alpha (1.3 mu m), P-alpha (3.75 mu m), the lin es of fine structure of the level n = 2 (1.62 cm, 2.30 cm and 3.48 cm) of t he ortho Ps and the spin-flip line (0.147 cm) from probable Galactic source s of a narrow annihilation line. The L-alpha line may be detected by HST fr om sources with small extinction in their direction. The observations of th e H-alpha and P-alpha lines are suitable for the best ground based IR teles copes. The maser lines of the fine structure may be observed on large radio telescopes since the population of the upper sublevel it = 2 is higher than the population of low sublevels.