Energy distribution and adiabatic guiding of a solid-neon-moderated positron beam

Ghosh, S.; Danielson, J. R.; Surko, C. M.

doi:10.1088/1361-6455/ab7642

Cited by 11 publications

(5 citation statements)

References 53 publications

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“…The use of the magnetic moment adiabatic invariant enables measurement of the perpendicular component by measurement of the mean parallel energy with the analyzer at different magnetic fields (see Refs. [50,54] for details). The time of flight of positrons through the RPA is used as a cross-check on the measured mean parallel energy of the beam.…”

Section: A Measurementsmentioning

confidence: 99%

Effect of chlorination on positron binding to hydrocarbons: Experiment and theory

et al. 2021

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Measured and calculated positron binding energies are presented for a range of hydrocarbons with up to six carbon atoms (viz., methane, acetylene, ethylene, ethane, propane, butane, and hexane) and their chlorinated counterparts. Both experiment and theory confirm the large effect that the chlorine atoms have on the positron binding energy and the strong sensitivity of the binding energy to the exact position of the chlorine atoms. The experimental binding energies have been obtained by measuring positron resonant annihilation using a trapbased positron beam. The calculations are performed using the previously developed model-correlation-potential method [A. R. Swann and G. F. Gribakin, J. Chem. Phys. 149, 244305 (2018)]. The overall trends are discussed with regard to the molecular polarizability, dipole moment, and geometry. Good agreement between theory and experiment is found, with the exception of the chlorinated ethylenes and chlorinated hexane. Calculations of the electron-positron annihilation rate in the bound state are also presented.

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Section: A Measurementsmentioning

confidence: 99%

Effect of chlorination on positron binding to hydrocarbons: Experiment and theory

et al. 2021

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“…The energy distribution is separated into the components associated with motion either parallel or perpendicular to the guiding magnetic field. During adiabatic transport (Ghosh, Danielson & Surko 2020), parallel and perpendicular energy are exchanged to simultaneously conserve the total energy, and the magnetic moment, Similarly, the electron beam expands and compresses with the magnetic field lines. The area of the beam in the plane perpendicular to the magnetic field is inversely proportional to the magnetic flux density.…”

Section: Resultsmentioning

confidence: 99%

Section: Electron Beammentioning

confidence: 99%

A buffer-gas trap for the NEPOMUC positron beam: optimization studies with electrons

Deller,

Rogge,

Desopo

et al. 2023

J. Plasma Phys.

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Buffer-gas traps (BGTs) use inelastic interactions with nitrogen molecules to capture positrons from a continuous beam. These devices are invaluable for high-resolution studies of matter–antimatter interactions, antihydrogen research and positronium laser spectroscopy. We present a new project with the goal of producing a non-neutral plasma containing ${\sim }10^8$ low-energy positrons by installing a BGT on the NEPOMUC (NEutron induced POsitron source MUniCh) high-intensity positron beam. Details of the BGT are outlined and results are presented from experiments in which an electron beam, with a similar intensity and energy spread to the remoderated NEPOMUC beam, was used to create pulses of non-neutral electron plasma. The device is a vital component of the APEX (A Positron Electron eXperiment) project, which aims to create a low-temperature electron–positron pair plasma.

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“…Annihilation gamma rays are measured while the beam interacts with the test gas. The beam energy distribution is measured using a retarding potential analyzer [1,30,33]. The count rate vs positron energy is converted into a normalized annihilation rate Z eff [29] using the known number of positrons per pulse, gas pressure, and detector calibration.…”

Section: Experimental Methodsmentioning

confidence: 99%

Influence of geometry on positron binding to molecules

Danielson¹,

Ghosh²,

Surko³

2021

J. Phys. B: At. Mol. Opt. Phys.

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Annihilation studies have established that positrons bind to most molecules. They also provide measurements of the positron-molecule binding energies, which are found to vary widely and depend upon molecular size and composition. Trends of binding energy with global parameters such as molecular polarizability and dipole moment have been discussed previously. In this paper, the dependence of binding energy on molecular geometry is investigated by studying resonant positron annihilation on selected pairs of isomers. It is found that molecular geometry can play a significant role in determining the binding energies even for isomers with very similar polarizabilities and dipole moments. The possible origins of this dependence are discussed.

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Energy distribution and adiabatic guiding of a solid-neon-moderated positron beam

Cited by 11 publications

References 53 publications

Effect of chlorination on positron binding to hydrocarbons: Experiment and theory

Effect of chlorination on positron binding to hydrocarbons: Experiment and theory

A buffer-gas trap for the NEPOMUC positron beam: optimization studies with electrons

Influence of geometry on positron binding to molecules

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