학술논문
Velocity selected production of $2^3S$ metastable positronium
Document Type
Working Paper
Author
Amsler, C.; Antonello, M.; Belov, A.; Bonomi, G.; Brusa, R. S.; Caccia, M.; Camper, A.; Caravita, R.; Castelli, F.; Cerchiari, G.; Comparat, D.; Consolati, G.; Demetrio, A.; Di Noto, L.; Doser, M.; Fanì, M.; Gerber, S.; Gligorova, A.; Guatieri, F.; Hackstock, P.; Haider, S.; Hinterberger, A.; Holmestad, H.; Kellerbauer, A.; Khalidova, O.; Krasnicky, D.; Lagomarsino, V.; Lansonneur, P.; Lebrun, P.; Malbrunot, C.; Mariazzi, S.; Matveev, V.; Muller, S. R.; Nebbia, G.; Nedelec, P.; Oberthaler, M.; Pagano, D.; Penasa, L.; Petracek, V.; Prelz, F.; Prevedelli, M.; Rienaecker, B.; Robert, J.; Rohne, O. M.; Rotondi, A.; Sandaker, H.; Santoro, R.; Smestad, L.; Sorrentino, F.; Testera, G.; Tietje, I. C.; Widmann, E.; Yzombard, P.; Zimmer, C.; Zurlo, N.
Source
Phys. Rev. A 99, 033405 (2019)
Subject
Language
Abstract
Positronium in the $2^3S$ 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, $2^3S$ positronium is produced - in absence of electric field - via spontaneous radiative decay from the $3^3P$ level populated with a 205nm 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 nanochannelled positron/positronium converter were selected by delaying the excitation pulse with respect to the production instant. $ 2^3S $ positronium atoms with velocity tuned between $ 7 \cdot 10^4 $ m/s and $ 10 \cdot 10^4 $ m/s were thus produced. Depending on the selected velocity, a $2^3S$ production effciency ranging from $\sim 0.8 \%$ to $\sim 1.7%$, with respect to the total amount of emitted positronium, was obtained. The observed results give a branching ratio for the $3^3P$-$2^3S$ spontaneous decay of $(9.7 \pm 2.7) \% $. The present velocity selection technique could allow to produce an almost monochromatic beam of $\sim 1 \cdot 10^3 $ $2^3S$ atoms with a velocity spread $ < 10^4 $ m/s and an angular divergence of $\sim$ 50 mrad.
Comment: 6 pages, 3 figures, 1 table
Comment: 6 pages, 3 figures, 1 table