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Title: Positron and laser studies for the formation of antihydrogen
Author: Mitchard, D. R. J.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2006
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The ATHENA Collaboration at CERN, Geneva, was a world leading experiment in the production of and experimentation with antihydrogen. By combining antiprotons and positrons, it was the first to produce cold antiatoms (a sample of 50,000) in 2002 and continues towards the primary aim of producing the most accurate test of the CPT theorem to date by comparing spectroscopic measurements of antihydrogen and hydrogen. This thesis is primarily concerned with investigations into the effect of a rotating electric field on a confined positron plasma under various conditions, with the aim of increasing understanding and improving the methods used to produce suitable plasmas for antihydrogen production. A phosphor screen and CCD camera apparatus was used to do this, which replaced a segmented Faraday cup. Results include the identification of several problems with the apparatus, such as probable magnetic asymmetries and potential steps, as well as some unexpected observations, such as a hollow positron beam and double positron plasmas. They also include the identification of critical parameters, primarily the critical positron density, before which the rotating electric field had little or no effect: how these parameters were affected by the various conditions of the accumulator (mainly the buffer gas pressure) was also investigated. Finally the results demonstrated in detail a complex accumulation process previously unknown whereby two plasmas were formed side-by-side, and only one was affected by the rotating electric field.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available