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Antihydrogen trapping assisted by sympathetically cooled positrons

N Madsen, F Robicheaux, S Jonsell, Niels Madsen Orcid Logo

New Journal of Physics, Volume: 16, Issue: 6, Start page: 063046

Swansea University Author: Niels Madsen Orcid Logo

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DOI (Published version): 10.1088/1367-2630/16/6/063046

Abstract

Antihydrogen, the bound state of an antiproton and a positron, is of interest for use in precision tests of nature's fundamental symmetries. Antihydrogen formed by carefully merging cold plasmas of positrons and antiprotons has recently been trapped in magnetic traps. The efficiency of trapping...

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Published in: New Journal of Physics
Published: 2014
Online Access: http://iopscience.iop.org/1367-2630/16/6/063046/
URI: https://cronfa.swan.ac.uk/Record/cronfa18049
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Abstract: Antihydrogen, the bound state of an antiproton and a positron, is of interest for use in precision tests of nature's fundamental symmetries. Antihydrogen formed by carefully merging cold plasmas of positrons and antiprotons has recently been trapped in magnetic traps. The efficiency of trapping is strongly dependent on the temperature of the nascent antihydrogen, which, to be trapped, must have a kinetic energy less than the trap depth of $\sim 0.5\;{\mbox{K}}\;{{k}_{B}}$. In the conditions in the ALPHA experiment, the antihydrogen temperature seems dominated by the temperature of the positron plasma used for the synthesis. Cold positrons are therefore of paramount interest in that experiment. In this paper, we propose an alternative route to make ultra-cold positrons for enhanced antihydrogen trapping. We investigate theoretically how to extend previously successful sympathetic cooling of positrons by laser-cooled positive ions to be used for antihydrogen trapping. Using simulations, we investigate the effectiveness of such cooling in conditions similar to those in ALPHA, and discuss how the formation process and the nascent antihydrogen may be influenced by the presence of positive ions. We argue that this technique is a viable alternative to methods such as evaporative and adiabatic cooling, and may overcome limitations faced by these. Ultra-cold positrons, once available, may also be of interest for a range of other applications.
Keywords: Antihydrogen, Laser cooling, Non-neutral plasma
College: College of Science
Issue: 6
Start Page: 063046