Laser excitation of the n=3 level of positronium for antihydrogen production

Aghion, S.; Amsler, C.; Ariga, A.; Ariga, T.; Bonomi, G.; Braunig, P.; Bremer, J.; Brusa, R. S.; Cabaret, L.; Caccia, M.; Caravita, R.; Castelli, F.; Cerchiari, G.; Chlouba, K.; Cialdi, S.; Comparat, D.; Consolati, G.; Demetrio, A.; Di Noto, L.; Doser, M.; Dudarev, A.; Ereditato, A.; Evans, C.; Ferragut, R.; Fesel, J.; Fontana, A.; Forslund, O. K.; Gerber, S.; Giammarchi, M.; Gligorova, A.; Gninenko, S.; Guatieri, F.; Haider, S.; Holmestad, H.; Huse, T.; Jernelv, I. L.; Jordan, E.; Kellerbauer, A.; Kimura, M.; Koettig, T.; Krasnicky, D.; Lagomarsino, V.; Lansonneur, P.; Lebrun, P.; Lehner, S.; Liberadzka, J.; Malbrunot, C.; Mariazzi, S.; Marx, L.; Matveev, V.; Mazzotta, Z.; Nebbia, G.; Nedelec, P.; Oberthaler, M.; Pacifico, N.; Pagano, D.; Penasa, L.; Petracek, V.; Pistillo, C.; Prelz, F.; Prevedelli, M.; Ravelli, L.; Resch, L.; Rienacker, B.; Rohne, O. M.; Rotondi, A.; Sacerdoti, M.; Sandaker, H.; Santoro, R.; Scampoli, P.; Smestad, L.; Sorrentino, F.; Spacek, M.; Storey, J.; Strojek, I. M.; Testera, G.; Tietje, I.; Vamosi, S.; Widmann, E.; Yzombard, P.; Zmeskal, J.; Zurlo, N.

doi:10.1103/PhysRevA.94.012507

We demonstrate the laser excitation of the n=3 state of positronium (Ps) in vacuum. A combination of a specially designed pulsed slow positron beam and a high-efficiency converter target was used to produce Ps. Its annihilation was recorded by single-shot positronium annihilation lifetime spectroscopy. Pulsed laser excitation of the n=3 level at a wavelength λ≈205 nm was monitored via Ps photoionization induced by a second intense laser pulse at λ=1064 nm. About 15% of the overall positronium emitted into vacuum was excited to n=3 and photoionized. Saturation of both the n=3 excitation and the following photoionization was observed and explained by a simple rate equation model. The positronium's transverse temperature was extracted by measuring the width of the Doppler-broadened absorption line. Moreover, excitation to Rydberg states n=15 and 16 using n=3 as the intermediate level was observed, giving an independent confirmation of excitation to the 3P3 state.

Laser excitation of the n=3 level of positronium for antihydrogen production

Aghion S.;Amsler C.;Ariga A.;Ariga T.;Bonomi G.;Braunig P.;Bremer J.;Brusa R. S.;Cabaret L.;Caccia M.;Caravita R.;Castelli F.;Cerchiari G.;Chlouba K.;Cialdi S.;Comparat D.;Consolati G.;Demetrio A.;Di Noto L.;Doser M.;Dudarev A.;Ereditato A.;Evans C.;Ferragut R.;Fesel J.;Fontana A.;Forslund O. K.;Gerber S.;Giammarchi M.;Gligorova A.;Gninenko S.;Guatieri F.;Haider S.;Holmestad H.;Huse T.;Jernelv I. L.;Jordan E.;Kellerbauer A.;Kimura M.;Koettig T.;Krasnicky D.;Lagomarsino V.;Lansonneur P.;Lebrun P.;Lehner S.;Liberadzka J.;Malbrunot C.;Mariazzi S.;Marx L.;Matveev V.;Mazzotta Z.;Nebbia G.;Nedelec P.;Oberthaler M.;Pacifico N.;Pagano D.;Penasa L.;Petracek V.;Pistillo C.;Prelz F.;Prevedelli M.;Ravelli L.;Resch L.;Rienacker B.;Rohne O. M.;Rotondi A.;Sacerdoti M.;Sandaker H.;Santoro R.;Scampoli P.;Smestad L.;Sorrentino F.;Spacek M.;Storey J.;Strojek I. M.;Testera G.;Tietje I.;Vamosi S.;Widmann E.;Yzombard P.;Zmeskal J.;Zurlo N.

2016-01-01

Abstract

We demonstrate the laser excitation of the n=3 state of positronium (Ps) in vacuum. A combination of a specially designed pulsed slow positron beam and a high-efficiency converter target was used to produce Ps. Its annihilation was recorded by single-shot positronium annihilation lifetime spectroscopy. Pulsed laser excitation of the n=3 level at a wavelength λ≈205 nm was monitored via Ps photoionization induced by a second intense laser pulse at λ=1064 nm. About 15% of the overall positronium emitted into vacuum was excited to n=3 and photoionized. Saturation of both the n=3 excitation and the following photoionization was observed and explained by a simple rate equation model. The positronium's transverse temperature was extracted by measuring the width of the Doppler-broadened absorption line. Moreover, excitation to Rydberg states n=15 and 16 using n=3 as the intermediate level was observed, giving an independent confirmation of excitation to the 3P3 state.