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Be+-Assisted Antihydrogen Synthesis and Trapping / MARIA GONCALVES

Swansea University Author: MARIA GONCALVES

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DOI (Published version): 10.23889/SUThesis.71615

Abstract

Antihydrogen, the bound state of a positron and an antiproton, is a uniquely well-suited system for testing fundamental symmetries between matter and antimatter. The Antihydrogen Laser Physics Apparatus (ALPHA collaboration) synthesises antihydrogen atoms by slowly merging cold non-neutral positron...

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Published: Swansea 2026
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Madsen, N.
URI: https://cronfa.swan.ac.uk/Record/cronfa71615
first_indexed 2026-03-12T11:26:14Z
last_indexed 2026-03-13T05:25:16Z
id cronfa71615
recordtype RisThesis
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spelling 2026-03-12T11:32:41.2426597 v2 71615 2026-03-12 Be+-Assisted Antihydrogen Synthesis and Trapping b03e12fa0d67ade5c771ae45afae0e1d MARIA GONCALVES MARIA GONCALVES true false 2026-03-12 Antihydrogen, the bound state of a positron and an antiproton, is a uniquely well-suited system for testing fundamental symmetries between matter and antimatter. The Antihydrogen Laser Physics Apparatus (ALPHA collaboration) synthesises antihydrogen atoms by slowly merging cold non-neutral positron and antiproton plasmas and traps the antiatoms in a magnetic minimum trap.While trapping efficiency has improved since its first demonstration in 2010, it plateaued after 2017.In ALPHA’s experimental conditions, antihydrogen is predominantly formed via three-body recombination, which has been theoretically and experimentally shown to strongly depend on the temperature of the positron plasma: lower positron temperatures yield higher antihydrogen trapping rates. In the ALPHA-2 trap, positrons alone reach a lower temperature limit of 15−20 K.The implementation of sympathetic cooling of positrons through collisions with laser-cooled Be+ions enabled stable lowering of these temperatures to below 10 K.This thesis describes the work towards antihydrogen synthesis with positrons prepared using this cooling method. A novel ion plasma preparation technique was developed to improve reproducibility, and a sophisticated control system with automated beam steering was implemented to ensure long-term operational stability. Moreover, the first demonstration of sympathetic cooling of positrons to < 10 K in a radially asymmetric magnetic field was carried out. Culminating in the first Be+-assisted antihydrogen synthesis and trapping. Careful optimisation of this technique resulted in a near eightfold increase in the antihydrogen trapping rate, and allowed for systematic studies of three-body recombination that were not possible before its implementation. Overall, this technique represents a paradigm shift for the ALPHA physics programme and provides a deeper understanding of antihydrogen synthesis, opening new avenues for precision studies of antimatter. E-Thesis Swansea Physics, Antimatter Physics, Atomic Physics 23 1 2026 2026-01-23 10.23889/SUThesis.71615 COLLEGE NANME COLLEGE CODE Swansea University Madsen, N. Doctoral Ph.D 2026-03-12T11:32:41.2426597 2026-03-12T11:17:20.2700971 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Physics MARIA GONCALVES 1 71615__36392__c97dc0b1ed8a4b2997fdf406045f014f.pdf 2025_Gomes_Gonvalves_M.final.71615.pdf 2026-03-12T11:23:45.9647192 Output 36281255 application/pdf E-Thesis – open access true Copyright: the author, Maria Beatriz Gomes Gonçalves, 2026. true eng
title Be+-Assisted Antihydrogen Synthesis and Trapping
spellingShingle Be+-Assisted Antihydrogen Synthesis and Trapping
MARIA GONCALVES
title_short Be+-Assisted Antihydrogen Synthesis and Trapping
title_full Be+-Assisted Antihydrogen Synthesis and Trapping
title_fullStr Be+-Assisted Antihydrogen Synthesis and Trapping
title_full_unstemmed Be+-Assisted Antihydrogen Synthesis and Trapping
title_sort Be+-Assisted Antihydrogen Synthesis and Trapping
author_id_str_mv b03e12fa0d67ade5c771ae45afae0e1d
author_id_fullname_str_mv b03e12fa0d67ade5c771ae45afae0e1d_***_MARIA GONCALVES
author MARIA GONCALVES
author2 MARIA GONCALVES
format E-Thesis
publishDate 2026
institution Swansea University
doi_str_mv 10.23889/SUThesis.71615
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Physics{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Physics
document_store_str 1
active_str 0
description Antihydrogen, the bound state of a positron and an antiproton, is a uniquely well-suited system for testing fundamental symmetries between matter and antimatter. The Antihydrogen Laser Physics Apparatus (ALPHA collaboration) synthesises antihydrogen atoms by slowly merging cold non-neutral positron and antiproton plasmas and traps the antiatoms in a magnetic minimum trap.While trapping efficiency has improved since its first demonstration in 2010, it plateaued after 2017.In ALPHA’s experimental conditions, antihydrogen is predominantly formed via three-body recombination, which has been theoretically and experimentally shown to strongly depend on the temperature of the positron plasma: lower positron temperatures yield higher antihydrogen trapping rates. In the ALPHA-2 trap, positrons alone reach a lower temperature limit of 15−20 K.The implementation of sympathetic cooling of positrons through collisions with laser-cooled Be+ions enabled stable lowering of these temperatures to below 10 K.This thesis describes the work towards antihydrogen synthesis with positrons prepared using this cooling method. A novel ion plasma preparation technique was developed to improve reproducibility, and a sophisticated control system with automated beam steering was implemented to ensure long-term operational stability. Moreover, the first demonstration of sympathetic cooling of positrons to < 10 K in a radially asymmetric magnetic field was carried out. Culminating in the first Be+-assisted antihydrogen synthesis and trapping. Careful optimisation of this technique resulted in a near eightfold increase in the antihydrogen trapping rate, and allowed for systematic studies of three-body recombination that were not possible before its implementation. Overall, this technique represents a paradigm shift for the ALPHA physics programme and provides a deeper understanding of antihydrogen synthesis, opening new avenues for precision studies of antimatter.
published_date 2026-01-23T05:25:16Z
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score 11.099629

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