| Verf.angabe: | C. Amsler, M. Antonello, A. Belov, G. Bonomi, R.S. Brusa, M. Caccia, A. Camper, R. Caravita, F. Castelli, G. Cerchiari, D. Comparat, G. Consolati, A. Demetrio, L. Di Noto, M. Doser, M. Fanì, S. Gerber, A. Gligorova, F. Guatieri, P. Hackstock, S. Haider, A. Hinterberger, H. Holmestad, A. Kellerbauer, O. Khalidova, D. Krasnický, V. Lagomarsino, P. Lansonneur, P. Lebrun, C. Malbrunot, S. Mariazzi, V. Matveev, S.R. Müller, G. Nebbia, P. Nedelec, M. Oberthaler, D. Pagano, L. Penasa, V. Petracek, F. Prelz, M. Prevedelli, B. Rienaecker, J. Robert, O.M. Røhne, A. Rotondi, H. Sandaker, R. Santoro, L. Smestad, F. Sorrentino, G. Testera, I.C. Tietje, E. Widmann, P. Yzombard, C. Zimmer, and N. Zurlo (The AEgIS Collaboration) |
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| Abstract: | Positronium in the 23S metastable state exhibits a low electrical polarizability and a long lifetime (1140 ns), making it a promising candidate for interferometry experiments with a neutral matter-antimatter system. In the present work, 23S positronium is produced, in the absence of an electric field, via spontaneous radiative decay from the 33P level populated with a 205-nm UV laser pulse. Thanks to the short temporal length of the pulse, 1.5 ns full width at half maximum, different velocity populations of a positronium cloud emitted from a nanochanneled positron-positronium converter were selected by delaying the excitation pulse with respect to the production instant. 23S positronium atoms with velocity tuned between 7×104ms−1 and 10×104ms−1 were thus produced. Depending on the selected velocity, a 23S production efficiency ranging from ∼0.8% to ∼1.7%, with respect to the total amount of emitted positronium, was obtained. The observed results give a branching ratio for the 33P−23S spontaneous decay of (9.7±2.7)%. The present velocity selection technique could allow one to produce an almost monochromatic beam of ∼1×10323S atoms with a velocity spread of <104ms−1 and an angular divergence of ∼50 mrad. |
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