Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Velocity-selected production of 23S metastable positronium

C. Amsler, M. Antonello, A. Belov, G Bonomi, Roberto Sennen Brusa, M. Caccia, A. Camper, R. Caravita, Castelli F, G. Cerchiari, D. Comparat, Giovanni Consolati, A. Demetrio, L. Di Noto, M. Doser, M. Fani, S. Gerber, A. Gligorova, F. Guatieri, P. Hackstock, S. Haider, A. Hinterberger, H. Holmestad, A. Kellerbauer, O. Khalidova, D. Krasnický, Vittorio Lagomarsino, P. Lansonneur, P. Lebrun, C. Malbrunot, S. Mariazzi, V. Matveev, S. Mueller, G. Nebbia, P. Nédélec, M. Oberthaler, D. Pagano, Luca Penasa, V. Petráček, F. Prelz, M. Prevedelli, Benjamin Rienaecker, Jacques Robert, Ole Myren Rohne, Alberto Rotondi, H. Sandaker, R. Santoro, L. Smestad, F. Sorrentino, G. Testera, Ingmari C. Tietje, E. Widmann, P. Yzombard, C. Zimmer, N. Zurlo

Published Mar 5, 2019• 0 citations
OpenAlex

Abstract

Positronium in the 2(3)S 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(3)S positronium is produced, in the absence of an electric field, via spontaneous radiative decay from the 3(3)P 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. 2(3)S positronium atoms with velocity tuned between 7 x 10(4) ms(-1) and 10 x 10(4) ms(-1) were thus produced. Depending on the selected velocity, a 2(3)S production efficiency ranging from similar to 0.8% to similar to 1.7%, with respect to the total amount of emitted positronium, was obtained. The observed results give a branching ratio for the 3(3)P-2(3)S spontaneous decay of (9.7 +/- 2.7)%. The present velocity selection technique could allow one to produce an almost monochromatic beam of similar to 1 x 10(3) 2(3)S atoms with a velocity spread of <10(4) ms(-1) and an angular divergence of similar to 50 mrad.

Related papers

Velocity-selected production of 2S3 metastable positronium

C. Amsler, M. Antonello, A. Belov +52 more

Positronium in the $2^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{S}$ 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, $2^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{S}$ positronium is produced, in the absence of an electric field, via spontaneous radiative decay from the $3^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{P}$ 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. $2^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{S}$ positronium atoms with velocity tuned between $7\ifmmode\times\else\texttimes\fi{}{10}^{4}\phantom{\rule{0.16em}{0ex}}{\mathrm{ms}}^{\ensuremath{-}1}$ and $10\ifmmode\times\else\texttimes\fi{}{10}^{4}\phantom{\rule{0.16em}{0ex}}{\mathrm{ms}}^{\ensuremath{-}1}$ were thus produced. Depending on the selected velocity, a $2^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{S}$ production efficiency ranging from $\ensuremath{\sim}0.8%$ to $\ensuremath{\sim}1.7%$, with respect to the total amount of emitted positronium, was obtained. The observed results give a branching ratio for the $3^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{P}\ensuremath{-}2^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{S}$ spontaneous decay of $(9.7\ifmmode\pm\else\textpm\fi{}2.7)%$. The present velocity selection technique could allow one to produce an almost monochromatic beam of $\ensuremath{\sim}1\ifmmode\times\else\texttimes\fi{}{10}^{3}\phantom{\rule{4pt}{0ex}}2^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{S}$ atoms with a velocity spread of $<{10}^{4}\phantom{\rule{0.16em}{0ex}}{\mathrm{ms}}^{\ensuremath{-}1}$ and an angular divergence of $\ensuremath{\sim}50$ mrad.

arXiv:1808.01808•Physical Review A•Mar 5, 2019•28 citations

Production of long-lived positronium states via laser excitation to 33P level

(The AEgIS collaboration)

The 33P state of positronium is an intermediate level suitable for producing long-lived positronium states. On one hand, it can be used in a two-step laser excitation scheme from the ground state to Rydberg levels. On the other hand, excitation of positronium to 33P level is a simple pathway for producing metastable 23S positronium atoms by spontaneous radiactive decay. In this work, experiments showing the production of such long-lived levels, using the 33P state as intermediate state, are presented. The characteristics of the two long-lived levels, in view of experiments of deflectometry/interferometry with positronium, are discussed.

AIP conference proceedings•Jan 1, 2019•1 citation

Efficient 2S3 positronium production by stimulated decay from the 3P3 level

M. Antonello, A. Belov, G. Bonomi +48 more

We investigate experimentally the possibility of enhancing the production of $2\phantom{\rule{0.16em}{0ex}}^{3}S$ positronium atoms by driving the $1\phantom{\rule{0.16em}{0ex}}^{3}S$--$3\phantom{\rule{0.16em}{0ex}}^{3}P$ and $3\phantom{\rule{0.16em}{0ex}}^{3}P$--$2\phantom{\rule{0.16em}{0ex}}^{3}S$ transitions, overcoming the natural branching ratio limitation of spontaneous decay from $3\phantom{\rule{0.16em}{0ex}}^{3}P$ to $2\phantom{\rule{0.16em}{0ex}}^{3}S$. The decay of $3\phantom{\rule{0.16em}{0ex}}^{3}P$ positronium atoms toward the $2\phantom{\rule{0.16em}{0ex}}^{3}S$ level has been efficiently stimulated by a 1312.2 nm broadband IR laser pulse. The dependence of the stimulating transition efficiency on the intensity of the IR pulse has been measured to find the optimal enhancement conditions. A maximum relative increase of $\ifmmode\times\else\texttimes\fi{}(3.1\ifmmode\pm\else\textpm\fi{}1.0)$ in the $2\phantom{\rule{0.16em}{0ex}}^{3}S$ production efficiency, with respect to the case in which only spontaneous decay is present, was obtained.

arXiv:1904.09004•Physical Review A•Dec 9, 2019•10 citations

Directed fluxes of positronium using pulsed travelling optical lattices

P. F. Barker, M. Charlton

The creation of directed fluxes of positronium atoms using the optical dipole force from short, pulsed travelling optical lattices has been studied. By exploiting the favourable polarizability-to-mass ratio of positronium it has been found that accelerations in excess of 10 14 g are possible. Simulations have been performed for several cases in which lattice beams capture a substantial fraction of a cloud of ground state ortho-positronium atoms, assumed to be characterised by an initial temperature of 300 K. We show that, using conventional laser sources, bunches of positronium atoms can be accelerated, well within the ortho-positronium vacuum lifetime of 142 ns, to a wide variety of kinetic energies in the eV to 100s of eV range and with well-defined energy spreads. The final kinetic energy of the positronium can be tuned using the laser intensity, the pulse duration or the rate of change of the frequency between the two beams which form the lattice.

New Journal of Physics•Apr 4, 2012•11 citations

Experimental progress in positronium laser physics

D. B. Cassidy

The field of experimental positronium physics has advanced significantly in the last few decades, with new areas of research driven by the development of techniques for trapping and manipulating positrons using Surko-type buffer gas traps. Large numbers of positrons (typically ≥106) accumulated in such a device may be ejected all at once, so as to generate an intense pulse. Standard bunching techniques can produce pulses with ns (mm) temporal (spatial) beam profiles. These pulses can be converted into a dilute Ps gas in vacuum with densities on the order of 107 cm−3 which can be probed by standard ns pulsed laser systems. This allows for the efficient production of excited Ps states, including long-lived Rydberg states, which in turn facilitates numerous experimental programs, such as precision optical and microwave spectroscopy of Ps, the application of Stark deceleration methods to guide, decelerate and focus Rydberg Ps beams, and studies of the interactions of such beams with other atomic and molecular species. These methods are also applicable to antihydrogen production and spectroscopic studies of energy levels and resonances in positronium ions and molecules. A summary of recent progress in this area will be given, with the objective of providing an overview of the field as it currently exists, and a brief discussion of some future directions.

The European Physical Journal D•Mar 1, 2018•169 citations

Controlling Positronium Annihilation with Electric Fields

A. Alonso, B. S. Cooper, Adam Deller +2 more

We show that the annihilation dynamics of excited positronium (Ps) atoms can be controlled using parallel electric and magnetic fields. To achieve this, Ps atoms were optically excited to n=2 sublevels in fields that were adjusted to control the amount of short-lived and long-lived character of the resulting mixed states. Inclusion of the former offers a practical approach to detection via annihilation radiation, whereas the increased lifetimes due to the latter can be exploited to optimize resonance-enhanced two-photon excitation processes (e.g., 1^{3}S→2^{3}P→nS/nD), either by minimizing losses through intermediate state decay, or by making it possible to separate the excitation laser pulses in time. In addition, photoexcitation of mixed states with a 2^{3}S_{1} component represents an efficient route to producing long-lived pure 2^{3}S_{1} atoms via single-photon excitation.

Physical Review Letters•Oct 27, 2015•19 citations
Positronium in the 2(3)S 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(3)S positronium is produced, in the absence of an electric field, via spontaneous radiative decay from the 3(3)P 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. 2(3)S positronium atoms with velocity tuned between 7 x 10(4) ms(-1) and 10 x 10(4) ms(-1) were thus produced. Depending on the selected velocity, a 2(3)S production efficiency ranging from similar to 0.8% to similar to 1.7%, with respect to the total amount of emitted positronium, was obtained. The observed results give a branching ratio for the 3(3)P-2(3)S spontaneous decay of (9.7 +/- 2.7)%. The present velocity selection technique could allow one to produce an almost monochromatic beam of similar to 1 x 10(3) 2(3)S atoms with a velocity spread of <10(4) ms(-1) and an angular divergence of similar to 50 mrad.
Positronium in the 23S2^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{S}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, 23S2^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{S}23S positronium is produced, in the absence of an electric field, via spontaneous radiative decay from the 33P3^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{P}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. 23S2^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{S}23S positronium atoms with velocity tuned between $7\ifmmode\times\else\texttimes\fi{}{10}^{4}\phantom{\rule{0.16em}{0ex}}{\mathrm{ms}}^{\ensuremath{-}1}$ and $10\ifmmode\times\else\texttimes\fi{}{10}^{4}\phantom{\rule{0.16em}{0ex}}{\mathrm{ms}}^{\ensuremath{-}1}$ were thus produced. Depending on the selected velocity, a 23S2^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{S}23S production efficiency ranging from $\ensuremath{\sim}0.8%$ to $\ensuremath{\sim}1.7%$, with respect to the total amount of emitted positronium, was obtained. The observed results give a branching ratio for the $3^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{P}\ensuremath{-}2^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{S}$ spontaneous decay of $(9.7\ifmmode\pm\else\textpm\fi{}2.7)%$. The present velocity selection technique could allow one to produce an almost monochromatic beam of $\ensuremath{\sim}1\ifmmode\times\else\texttimes\fi{}{10}^{3}\phantom{\rule{4pt}{0ex}}2^{\phantom{\rule{0.16em}{0ex}}3}\mathrm{S}$ atoms with a velocity spread of $<{10}^{4}\phantom{\rule{0.16em}{0ex}}{\mathrm{ms}}^{\ensuremath{-}1}$ and an angular divergence of $\ensuremath{\sim}50$ mrad.
The 33P state of positronium is an intermediate level suitable for producing long-lived positronium states. On one hand, it can be used in a two-step laser excitation scheme from the ground state to Rydberg levels. On the other hand, excitation of positronium to 33P level is a simple pathway for producing metastable 23S positronium atoms by spontaneous radiactive decay. In this work, experiments showing the production of such long-lived levels, using the 33P state as intermediate state, are presented. The characteristics of the two long-lived levels, in view of experiments of deflectometry/interferometry with positronium, are discussed.
We investigate experimentally the possibility of enhancing the production of 23S2\phantom{\rule{0.16em}{0ex}}^{3}S23S positronium atoms by driving the 13S1\phantom{\rule{0.16em}{0ex}}^{3}S13S--33P3\phantom{\rule{0.16em}{0ex}}^{3}P33P and 33P3\phantom{\rule{0.16em}{0ex}}^{3}P33P--23S2\phantom{\rule{0.16em}{0ex}}^{3}S23S transitions, overcoming the natural branching ratio limitation of spontaneous decay from 33P3\phantom{\rule{0.16em}{0ex}}^{3}P33P to 23S2\phantom{\rule{0.16em}{0ex}}^{3}S23S. The decay of 33P3\phantom{\rule{0.16em}{0ex}}^{3}P33P positronium atoms toward the 23S2\phantom{\rule{0.16em}{0ex}}^{3}S23S level has been efficiently stimulated by a 1312.2 nm broadband IR laser pulse. The dependence of the stimulating transition efficiency on the intensity of the IR pulse has been measured to find the optimal enhancement conditions. A maximum relative increase of $\ifmmode\times\else\texttimes\fi{}(3.1\ifmmode\pm\else\textpm\fi{}1.0)$ in the 23S2\phantom{\rule{0.16em}{0ex}}^{3}S23S production efficiency, with respect to the case in which only spontaneous decay is present, was obtained.
The creation of directed fluxes of positronium atoms using the optical dipole force from short, pulsed travelling optical lattices has been studied. By exploiting the favourable polarizability-to-mass ratio of positronium it has been found that accelerations in excess of 10 14 g are possible. Simulations have been performed for several cases in which lattice beams capture a substantial fraction of a cloud of ground state ortho-positronium atoms, assumed to be characterised by an initial temperature of 300 K. We show that, using conventional laser sources, bunches of positronium atoms can be accelerated, well within the ortho-positronium vacuum lifetime of 142 ns, to a wide variety of kinetic energies in the eV to 100s of eV range and with well-defined energy spreads. The final kinetic energy of the positronium can be tuned using the laser intensity, the pulse duration or the rate of change of the frequency between the two beams which form the lattice.
The field of experimental positronium physics has advanced significantly in the last few decades, with new areas of research driven by the development of techniques for trapping and manipulating positrons using Surko-type buffer gas traps. Large numbers of positrons (typically ≥106) accumulated in such a device may be ejected all at once, so as to generate an intense pulse. Standard bunching techniques can produce pulses with ns (mm) temporal (spatial) beam profiles. These pulses can be converted into a dilute Ps gas in vacuum with densities on the order of 107 cm−3 which can be probed by standard ns pulsed laser systems. This allows for the efficient production of excited Ps states, including long-lived Rydberg states, which in turn facilitates numerous experimental programs, such as precision optical and microwave spectroscopy of Ps, the application of Stark deceleration methods to guide, decelerate and focus Rydberg Ps beams, and studies of the interactions of such beams with other atomic and molecular species. These methods are also applicable to antihydrogen production and spectroscopic studies of energy levels and resonances in positronium ions and molecules. A summary of recent progress in this area will be given, with the objective of providing an overview of the field as it currently exists, and a brief discussion of some future directions.
We show that the annihilation dynamics of excited positronium (Ps) atoms can be controlled using parallel electric and magnetic fields. To achieve this, Ps atoms were optically excited to n=2 sublevels in fields that were adjusted to control the amount of short-lived and long-lived character of the resulting mixed states. Inclusion of the former offers a practical approach to detection via annihilation radiation, whereas the increased lifetimes due to the latter can be exploited to optimize resonance-enhanced two-photon excitation processes (e.g., 1^{3}S→2^{3}P→nS/nD), either by minimizing losses through intermediate state decay, or by making it possible to separate the excitation laser pulses in time. In addition, photoexcitation of mixed states with a 2^{3}S_{1} component represents an efficient route to producing long-lived pure 2^{3}S_{1} atoms via single-photon excitation.