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Berghold M, Burwitz VV, Mathes L, Hugenschmidt C, Guatieri F. Imaging low-energy positron beams in real-time with unprecedented resolution. Sci Rep 2023; 13:18526. [PMID: 37898652 PMCID: PMC10613302 DOI: 10.1038/s41598-023-45588-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 10/21/2023] [Indexed: 10/30/2023] Open
Abstract
Particle beams focused to micrometer-sized spots play a crucial role in forefront research using low-energy positrons. Their expedient and wide application, however, requires highly-resolved, fast beam diagnostics. We have developed two different methods to modify a commercial imaging sensor to make it sensitive to low-energy positrons. The first method consists in removing the micro-lens array and Bayer filter from the sensor surface and depositing a phosphor layer in their place. This procedure results in a detector capable of imaging positron beams with energies down to a few tens of eV, or an intensity as low as [Formula: see text] when the beam energy exceeds 10 [Formula: see text]. The second approach omits the phosphor deposition; with the resulting device we succeeded in detecting single positrons with energies upwards of [Formula: see text] and efficiency up to 93%. The achieved spatial resolution of 0.97 [Formula: see text] is unprecedented for real-time positron detectors.
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Affiliation(s)
- Michael Berghold
- Research Neutron Source Heinz Maier-Leibnitz (FRM II), Technical University of Munich, Lichtenbergstr. 1, 85748, Garching bei München, Bavaria, Germany
| | - Vassily Vadimovitch Burwitz
- Research Neutron Source Heinz Maier-Leibnitz (FRM II), Technical University of Munich, Lichtenbergstr. 1, 85748, Garching bei München, Bavaria, Germany
| | - Lucian Mathes
- Research Neutron Source Heinz Maier-Leibnitz (FRM II), Technical University of Munich, Lichtenbergstr. 1, 85748, Garching bei München, Bavaria, Germany
| | - Christoph Hugenschmidt
- Research Neutron Source Heinz Maier-Leibnitz (FRM II), Technical University of Munich, Lichtenbergstr. 1, 85748, Garching bei München, Bavaria, Germany
| | - Francesco Guatieri
- Research Neutron Source Heinz Maier-Leibnitz (FRM II), Technical University of Munich, Lichtenbergstr. 1, 85748, Garching bei München, Bavaria, Germany.
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Hofierka J, Cunningham B, Rawlins CM, Patterson CH, Green DG. Many-body theory of positron binding to polyatomic molecules. Nature 2022; 606:688-693. [PMID: 35732760 PMCID: PMC9217750 DOI: 10.1038/s41586-022-04703-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 03/30/2022] [Indexed: 02/01/2023]
Abstract
Positron binding to molecules is key to extremely enhanced positron annihilation and positron-based molecular spectroscopy1. Although positron binding energies have been measured for about 90 polyatomic molecules1-6, an accurate ab initio theoretical description of positron-molecule binding has remained elusive. Of the molecules studied experimentally, ab initio calculations exist for only six; these calculations agree with experiments on polar molecules to at best 25 per cent accuracy and fail to predict binding in nonpolar molecules. The theoretical challenge stems from the need to accurately describe the strong many-body correlations including polarization of the electron cloud, screening of the electron-positron Coulomb interaction and the unique process of virtual-positronium formation (in which a molecular electron temporarily tunnels to the positron)1. Here we develop a many-body theory of positron-molecule interactions that achieves excellent agreement with experiment (to within 1 per cent in cases) and predicts binding in formamide and nucleobases. Our framework quantitatively captures the role of many-body correlations and shows their crucial effect on enhancing binding in polar molecules, enabling binding in nonpolar molecules, and increasing annihilation rates by 2 to 3 orders of magnitude. Our many-body approach can be extended to positron scattering and annihilation γ-ray spectra in molecules and condensed matter, to provide the fundamental insight and predictive capability required to improve materials science diagnostics7,8, develop antimatter-based technologies (including positron traps, beams and positron emission tomography)8-10, and understand positrons in the Galaxy11.
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Affiliation(s)
- Jaroslav Hofierka
- School of Mathematics and Physics, Queen's University Belfast, Belfast, UK
| | - Brian Cunningham
- School of Mathematics and Physics, Queen's University Belfast, Belfast, UK
| | - Charlie M Rawlins
- School of Mathematics and Physics, Queen's University Belfast, Belfast, UK
| | | | - Dermot G Green
- School of Mathematics and Physics, Queen's University Belfast, Belfast, UK.
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3
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Singer M, König S, Stoneking MR, Steinbrunner P, Danielson JR, Schweikhard L, Pedersen TS. Non-neutral plasma manipulation techniques in development of a high-capacity positron trap. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:123504. [PMID: 34972413 DOI: 10.1063/5.0067666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 11/09/2021] [Indexed: 06/14/2023]
Abstract
Preliminary experiments have been performed toward the development of a multi-cell Penning-Malmberg trap for the storage of large numbers of positrons (≥1010 e+). We introduce the master-cell test trap and the diagnostic tools for first experiments with electrons. The usage of a phosphor screen to measure the z-integrated plasma distribution and the number of confined particles is demonstrated, as well as the trap alignment to the magnetic field (B = 3.1 T) using the m = 1 diocotron mode. The plasma parameters and expansion are described along with the autoresonant excitation of the diocotron mode using rotating dipole fields and frequency chirped sinusoidal drive signals. We analyze the reproducibility of the excitation and use these findings to settle on the path for the next generation multi-cell test device.
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Affiliation(s)
- M Singer
- Max-Planck Institute for Plasma Physics, 17491 Greifswald, Germany
| | - S König
- University of Greifswald, 17489 Greifswald, Germany
| | - M R Stoneking
- Max-Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - P Steinbrunner
- Max-Planck Institute for Plasma Physics, 17491 Greifswald, Germany
| | - J R Danielson
- University of California, San Diego, La Jolla, California 92093, USA
| | | | - T Sunn Pedersen
- Max-Planck Institute for Plasma Physics, 17491 Greifswald, Germany
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Pietrow M, Zaleski R, Wagner A, Słomski P, Hirschmann E, Krause-Rehberg R, Liedke MO, Butterling M, Weinberger D. An experimental investigation of light emission produced in the process of positronium formation in matter. Phys Chem Chem Phys 2021; 23:11264-11271. [PMID: 33950060 DOI: 10.1039/d1cp00755f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The excess energy emitted during the positronium (Ps) formation in condensed matter may be released as light. Spectroscopic analysis of this light can be a new method of studying the electronic properties of materials. We report the first experimental attempt, according to our knowledge, to verify the existence of this emission process. As a result, the possibility of the emission of photons during Ps formation is within the experimental uncertainty in two different solids: an n-alkane and porous silica. However, it seems that the Ps formation on the alkane surface is not accompanied by the emission of photons with energy in the detection range of 1.6-3.8 eV. Various processes that can influence the energy of the photon emitted during the Ps formation are discussed to elucidate this issue. To aid future experiments, equations were developed to estimate the expected ratio of light emission events to annihilation events with the presence or absence of a photon during the Ps formation.
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Affiliation(s)
- M Pietrow
- Institute of Physics, M. Curie-Skłodowska University, ul. Pl. M. Curie-Skłodowskiej 1, 20-031 Lublin, Poland.
| | - R Zaleski
- Institute of Physics, M. Curie-Skłodowska University, ul. Pl. M. Curie-Skłodowskiej 1, 20-031 Lublin, Poland.
| | - A Wagner
- Institut für Strahlenphysik/Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden, Germany
| | - P Słomski
- IT Company Martinex, ul. Mełgiewska 95, 21-040 Swidnik, Poland
| | - E Hirschmann
- Institut für Strahlenphysik/Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden, Germany
| | - R Krause-Rehberg
- Institut für Physik, Universität Halle, von-Danckelmann-Platz 3, 06120 Halle, Germany
| | - M O Liedke
- Institut für Strahlenphysik/Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden, Germany
| | - M Butterling
- Institut für Strahlenphysik/Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden, Germany
| | - D Weinberger
- Institut für Strahlenphysik/Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden, Germany
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Chirayath VA, Gladen RW, McDonald AD, Fairchild AJ, Joglekar PV, Satyal S, Lim ZH, Shead TN, Chrysler MD, Mukherjee S, Barnett BM, Byrnes NK, Koymen AR, Greaves RG, Weiss AH. A multi-stop time-of-flight spectrometer for the measurement of positron annihilation-induced electrons in coincidence with the Doppler-shifted annihilation gamma photon. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:033903. [PMID: 32260020 DOI: 10.1063/1.5140789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Accepted: 02/07/2020] [Indexed: 06/11/2023]
Abstract
In this study, we describe an advanced multi-functional, variable-energy positron beam system capable of measuring the energies of multiple "positron-induced" electrons in coincidence with the Doppler-shifted gamma photon resulting from the annihilation of the correlated positron. The measurements were carried out using the unique characteristics of the digital time-of-flight spectrometer and the gamma spectrometer available with the advanced positron beam system. These measurements have resulted in (i) the first digital time-of-flight spectrum of positron annihilation-induced Auger electrons generated using coincident signals from a high-purity Ge detector and a micro-channel plate, (ii) a two-dimensional array of the energy of Doppler-broadened annihilation gamma and the time-of-flight of positron-annihilation induced Auger electrons/secondary electrons measured in coincidence with the annihilation gamma photon, and (iii) the time-of-flight spectra of multiple secondary electrons ejected from a bilayer graphene surface as a result of the impact and/or annihilation of positrons. The novelty of the gamma-electron coincidence spectroscopy has been demonstrated by extracting the Doppler-broadened spectrum of gamma photons emitted due to the annihilation of positrons exclusively with 1s electrons of carbon. The width of the extracted Doppler-broadened gamma spectrum has been found to be consistent with the expected broadening of the annihilation gamma spectrum due to the momentum of the 1s electrons in carbon.
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Affiliation(s)
- V A Chirayath
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - R W Gladen
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - A D McDonald
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - A J Fairchild
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - P V Joglekar
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - S Satyal
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - Z H Lim
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - T N Shead
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - M D Chrysler
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - S Mukherjee
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - B M Barnett
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - N K Byrnes
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - A R Koymen
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - R G Greaves
- First Point Scientific Inc., Agoura Hills, California 91301, USA
| | - A H Weiss
- Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA
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