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Michishio K, Chiari L, Tanaka F, Nagashima Y. Anisotropic Photodetachment of Positronium Negative Ions with Linearly Polarized Light. PHYSICAL REVIEW LETTERS 2024; 132:203001. [PMID: 38829062 DOI: 10.1103/physrevlett.132.203001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 03/25/2024] [Accepted: 04/18/2024] [Indexed: 06/05/2024]
Abstract
We report on the anisotropic photodetachment of positronium negative ions, followed by the dissociation into p-wave electrons and positronium atoms, with a linearly polarized laser beam. We have observed a strong recoil effect of the photoelectrons on the translation momentum of the dissociated positronium atoms. With polarization angle-resolved measurements, the asymmetry parameter of the photoemission angular distribution of the ions at a photon energy of 1.165 eV was determined to be 1.97±0.04(stat)±0.07(syst), in agreement with a theoretical prediction. The present method can be applied to explore the unrevealed dissociation dynamics of exotic particle systems and their manipulation with polarized light.
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Affiliation(s)
- Koji Michishio
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
| | - Luca Chiari
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
- Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan
| | - Fumi Tanaka
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
| | - Yasuyuki Nagashima
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
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Morgan AA, Hogan SD. Coupling Rydberg Atoms to Microwave Fields in a Superconducting Coplanar Waveguide Resonator. PHYSICAL REVIEW LETTERS 2020; 124:193604. [PMID: 32469590 DOI: 10.1103/physrevlett.124.193604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 04/27/2020] [Indexed: 06/11/2023]
Abstract
Rydberg helium atoms traveling in pulsed supersonic beams have been coupled to microwave fields in a superconducting coplanar waveguide (CPW) resonator. The atoms were initially prepared in the 1s55s ^{3}S_{1} Rydberg level by two-color two-photon laser excitation from the metastable 1s2s ^{3}S_{1} level. Two-photon microwave transitions between the 1s55s ^{3}S_{1} and 1s56s ^{3}S_{1} levels were then driven by the 19.556 GHz third-harmonic microwave field in a quarter-wave CPW resonator. This superconducting microwave resonator was fabricated from niobium nitride on a silicon substrate and operated at temperatures between 3.65 and 4.30 K. The populations of the Rydberg levels in the experiments were determined by state-selective pulsed electric field ionization. The coherence of the atom-resonator coupling was studied by time-domain measurements of Rabi oscillations.
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Affiliation(s)
- A A Morgan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - S D Hogan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Michishio K, Chiari L, Tanaka F, Oshima N, Nagashima Y. A high-quality and energy-tunable positronium beam system employing a trap-based positron beam. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:023305. [PMID: 30831693 DOI: 10.1063/1.5060619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 01/17/2019] [Indexed: 06/09/2023]
Abstract
We constructed a new apparatus, built upon a trap-based slow positron beam, for the production of a collimated, energy-tunable positronium beam under ultra-high vacuum conditions employing the photodetachment of positronium negative ions. A slow positron generator consisting of a 22Na radioisotope (20 mCi) combined with a buffer-gas positron trap is employed to generate high-quality, nano-second positron bursts with a repetition rate of 1 Hz-1 kHz. The positron bursts are focused onto an efficient positron-to-positronium negative ion converter, a Na-coated W thin film in a transmission geometry, using a magnetic lens system. The ions emitted from the opposite surface of the film are electrostatically accelerated to a given energy and photodetached by a pulsed infrared laser to form a mono-energetic positronium beam with kinetic energies of 0.2 keV-3.3 keV. The achieved detection rate of Ps atoms is 23 cps at the energy of 3.3 keV with a signal-to-background ratio as high as 300. The energy spread of the beam was evaluated by comparing the result of the time-of-flight measurements and particle-tracking simulations. With the use of a collimator of 1 mm diameter, a coherent beam with an angular divergence of less than 0.3° is obtained. The obtained Ps beam, having a much higher quality than those reported hitherto, will open up a new field of experimental investigations, such as Ps interacting with a variety of materials and fundamental studies on Ps spectroscopy.
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Affiliation(s)
- K Michishio
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
| | - L Chiari
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
| | - F Tanaka
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
| | - N Oshima
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Y Nagashima
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
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Kadyrov AS, Bray I, Charlton M, Fabrikant II. Quantum suppression of antihydrogen formation in positronium-antiproton scattering. Nat Commun 2017; 8:1544. [PMID: 29146898 PMCID: PMC5691179 DOI: 10.1038/s41467-017-01721-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 10/10/2017] [Indexed: 11/08/2022] Open
Abstract
The interaction of antiprotons with low-energy positronium atoms is a fundamental three-body problem whose significance is its utility for formation of antihydrogen. Particular importance resides in understanding processes involving excited positronium states. Until recently such studies were performed using classical techniques. However, they become inapplicable in the low-energy domain. Here we report the results of comprehensive quantum calculations, which include initial excited positronium states with principal quantum numbers up to n i = 5. Contrary to expectation from earlier work, there are only muted increases in the cross-sections for antihydrogen formation for n i > 3. We interpret this in terms of quantum suppression of the reaction at higher angular momenta. Furthermore, the cross-sections for elastic scattering are around two orders of magnitude higher, which we attribute to the degeneracy of the positronium states. We outline some experimental consequences of our results.
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Affiliation(s)
- A S Kadyrov
- Curtin Institute for Computation and Department of Physics, Astronomy and Medical Radiation Science, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia.
| | - I Bray
- Curtin Institute for Computation and Department of Physics, Astronomy and Medical Radiation Science, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia
| | - M Charlton
- Department of Physics, College of Science, Swansea University, Swansea, SA2 8PP, UK
| | - I I Fabrikant
- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, 68588-0299, USA
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Jones ACL, Piñeiro AM, Roeder EE, Rutbeck-Goldman HJ, Tom HWK, Mills AP. Large-area field-ionization detector for the study of Rydberg atoms. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:113307. [PMID: 27910370 DOI: 10.1063/1.4967305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We describe here the development and characterization of a micro-channel plate (MCP) based detector designed for the efficient collection and detection of Rydberg positronium (Ps) atoms for use in a time-of-flight apparatus. The designed detector collects Rydberg atoms over a large area (∼4 times greater than the active area of the MCP), ionizing incident atoms and then collecting and focusing the freed positrons onto the MCP. Here we discuss the function, design, and optimization of the device. The detector has an efficiency for Rydberg Ps that is two times larger than that of the γ-ray scintillation detector based scheme it has been designed to replace, with half the background signal. In principle, detectors of the type described here could be readily employed for the detection of any Rydberg atom species, provided a sufficient field can be applied to achieve an ionization rate of ≥108/s. In such cases, the best time resolution would be achieved by collecting ionized electrons rather than the positive ions.
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Affiliation(s)
- A C L Jones
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - A M Piñeiro
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - E E Roeder
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - H J Rutbeck-Goldman
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - H W K Tom
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - A P Mills
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
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Deller A, Alonso AM, Cooper BS, Hogan SD, Cassidy DB. Electrostatically Guided Rydberg Positronium. PHYSICAL REVIEW LETTERS 2016; 117:073202. [PMID: 27563960 DOI: 10.1103/physrevlett.117.073202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Indexed: 06/06/2023]
Abstract
We report experiments in which positronium (Ps) atoms were guided using inhomogeneous electric fields. Ps atoms in Rydberg-Stark states with principal quantum number n=10 and electric dipole moments up to 610 D were prepared via two-color two-photon optical excitation in the presence of a 670 V cm^{-1} electric field. The Ps atoms were created at the entrance of a 0.4 m long electrostatic quadrupole guide, and were detected at the end of the guide via annihilation gamma radiation. When the lasers were tuned to excite low-field-seeking Stark states, a fivefold increase in the number of atoms reaching the end of the guide was observed, whereas no signal was detected when high-field-seeking states were produced. The data are consistent with the calculated geometrical guide acceptance.
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Affiliation(s)
- A Deller
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - A M Alonso
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - B S Cooper
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - S D Hogan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - D B Cassidy
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Hogan SD. Rydberg-Stark deceleration of atoms and molecules. EPJ TECHNIQUES AND INSTRUMENTATION 2016; 3:2. [PMID: 32355605 PMCID: PMC7175735 DOI: 10.1140/epjti/s40485-015-0028-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 12/27/2015] [Indexed: 06/06/2023]
Abstract
The large electric dipole moments associated with highly excited Rydberg states of atoms and molecules make gas-phase samples in these states very well suited to deceleration and trapping using inhomogeneous electric fields. The methods of Rydberg-Stark deceleration with which this can be achieved are reviewed here. Using these techniques, the longitudinal motion of beams of atoms and molecules moving at speeds as high as 2500 m/s have been manipulated, with changes in kinetic energy of up to |Δ E kin|=1.3×10-20 J (|Δ E kin|/e=80 meV or |Δ E kin|/h c=650 cm -1) achieved, while decelerated and trapped samples with number densities of 106- 107 cm -3 and translational temperatures of ∼150 mK have been prepared. Applications of these samples in areas of research at the interface between physics and physical chemistry are discussed.
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Affiliation(s)
- Stephen D. Hogan
- Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT UK
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Kellerbauer A, Aghion S, Amsler C, Ariga A, Ariga T, Bonomi G, Bräunig P, Bremer J, Brusa RS, 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, Gerber S, Giammarchi M, Gligorova A, Guatieri F, Haider S, Holmestad H, Huse T, Jordan E, Kimura M, Koettig T, Krasnický D, Lagomarsino V, Lansonneur P, Lebrun P, Lehner S, Liberadzka J, Malbrunot C, Mariazzi S, Matveev V, Mazzotta Z, Nebbia G, Nédélec P, Oberthaler M, Pacifico N, Pagano D, Penasa L, Petráček V, Pistillo C, Prelz F, Prevedelli M, Ravelli L, Rienäcker B, Røhne O, Rotondi A, Sacerdoti M, Sandaker H, Santoro R, Scampoli P, Smestad L, Sorrentino F, Špaček M, Storey J, Strojek I, Testera G, Tietje I, Widmann E, Yzombard P, Zavatarelli S, Zmeskal J, Zurlo N. Probing antimatter gravity – The AEGIS experiment at CERN. EPJ WEB OF CONFERENCES 2016. [DOI: 10.1051/epjconf/201612602016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Alonso AM, Cooper BS, Deller A, Hogan SD, Cassidy DB. Controlling Positronium Annihilation with Electric Fields. PHYSICAL REVIEW LETTERS 2015; 115:183401. [PMID: 26565466 DOI: 10.1103/physrevlett.115.183401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Indexed: 06/05/2023]
Abstract
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.
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Affiliation(s)
- A M Alonso
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - B S Cooper
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - A Deller
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - S D Hogan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - D B Cassidy
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Cooper BS, Alonso AM, Deller A, Wall TE, Cassidy DB. A trap-based pulsed positron beam optimised for positronium laser spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:103101. [PMID: 26520934 DOI: 10.1063/1.4931690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We describe a pulsed positron beam that is optimised for positronium (Ps) laser-spectroscopy experiments. The system is based on a two-stage Surko-type buffer gas trap that produces 4 ns wide pulses containing up to 5 × 10(5) positrons at a rate of 0.5-10 Hz. By implanting positrons from the trap into a suitable target material, a dilute positronium gas with an initial density of the order of 10(7) cm(-3) is created in vacuum. This is then probed with pulsed (ns) laser systems, where various Ps-laser interactions have been observed via changes in Ps annihilation rates using a fast gamma ray detector. We demonstrate the capabilities of the apparatus and detection methodology via the observation of Rydberg positronium atoms with principal quantum numbers ranging from 11 to 22 and the Stark broadening of the n = 2 → 11 transition in electric fields.
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Affiliation(s)
- B S Cooper
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - A M Alonso
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - A Deller
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - T E Wall
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - D B Cassidy
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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