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Cold antihydrogen experiments and radial compression of antiproton clouds in the ALPHA apparatus at CERN

Antihydrogen is the simplest neutral antimatter atom. Precision comparisons between hydrogen and antihydrogen would provide stringent tests of CPT (charge conjugation/parity transformation/time reversal) invariance and the weak equivalence principle. In the last few years, the ALPHA collaboration ha...

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Autor principal: Gutierrez, A
Lenguaje:eng
Publicado: 2017
Materias:
Acceso en línea:http://cds.cern.ch/record/2284129
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author Gutierrez, A
author_facet Gutierrez, A
author_sort Gutierrez, A
collection CERN
description Antihydrogen is the simplest neutral antimatter atom. Precision comparisons between hydrogen and antihydrogen would provide stringent tests of CPT (charge conjugation/parity transformation/time reversal) invariance and the weak equivalence principle. In the last few years, the ALPHA collaboration has produced, and trapped antihydrogen. Most recently, this collaboration has probed antihydrogen’s internal structure by inducing hyperfine transitions in ground state atoms. In this thesis, many details of the cold antihydrogen formation, trapping and measurements of antihydrogen performed in the ALPHA apparatus are presented, with a focus on antiproton cloud compression. Such compression is an important tool for the formation and trapping of cold antihydrogen, since it allows control of the radial size and density of the antiproton cloud. Compression of non-neutral plasmas can be achieved using a rotating time-varying azimuthal electric field, which has been called rotating wall technique. In this work, we have observed a new mechanism for compression of a non-neutral plasma, specifically where antiprotons embedded in an electron plasma are compressed by a rotating wall drive at a frequency close to the sum of the axial bounce and rotation frequencies (in a frequency range of 50 – 750 kHz). The radius of the antiproton cloud is reduced by up to a factor of 20 with the smallest radius measured to be ∼ 0.2 mm. We have studied antiproton cloud compression as a function of the rotating wall frequency, the duration of compression, the rotating wall amplitude, the numbers of electrons and antiprotons, the magnetic field and the shape of the potential well. The frequency range over which compression is evident is compared to the sum of the antiproton bounce frequency and the system’s rotation frequency. It is suggested that bounce resonant transport is a likely explanation for the compression of antiproton clouds in this regime.
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spelling oai-inspirehep.net-16209712020-11-06T12:44:28Zhttp://cds.cern.ch/record/2284129engGutierrez, ACold antihydrogen experiments and radial compression of antiproton clouds in the ALPHA apparatus at CERNPhysics in GeneralAntihydrogen is the simplest neutral antimatter atom. Precision comparisons between hydrogen and antihydrogen would provide stringent tests of CPT (charge conjugation/parity transformation/time reversal) invariance and the weak equivalence principle. In the last few years, the ALPHA collaboration has produced, and trapped antihydrogen. Most recently, this collaboration has probed antihydrogen’s internal structure by inducing hyperfine transitions in ground state atoms. In this thesis, many details of the cold antihydrogen formation, trapping and measurements of antihydrogen performed in the ALPHA apparatus are presented, with a focus on antiproton cloud compression. Such compression is an important tool for the formation and trapping of cold antihydrogen, since it allows control of the radial size and density of the antiproton cloud. Compression of non-neutral plasmas can be achieved using a rotating time-varying azimuthal electric field, which has been called rotating wall technique. In this work, we have observed a new mechanism for compression of a non-neutral plasma, specifically where antiprotons embedded in an electron plasma are compressed by a rotating wall drive at a frequency close to the sum of the axial bounce and rotation frequencies (in a frequency range of 50 – 750 kHz). The radius of the antiproton cloud is reduced by up to a factor of 20 with the smallest radius measured to be ∼ 0.2 mm. We have studied antiproton cloud compression as a function of the rotating wall frequency, the duration of compression, the rotating wall amplitude, the numbers of electrons and antiprotons, the magnetic field and the shape of the potential well. The frequency range over which compression is evident is compared to the sum of the antiproton bounce frequency and the system’s rotation frequency. It is suggested that bounce resonant transport is a likely explanation for the compression of antiproton clouds in this regime.CERN-THESIS-2016-333oai:inspirehep.net:16209712017-09-14T08:00:22Z
spellingShingle Physics in General
Gutierrez, A
Cold antihydrogen experiments and radial compression of antiproton clouds in the ALPHA apparatus at CERN
title Cold antihydrogen experiments and radial compression of antiproton clouds in the ALPHA apparatus at CERN
title_full Cold antihydrogen experiments and radial compression of antiproton clouds in the ALPHA apparatus at CERN
title_fullStr Cold antihydrogen experiments and radial compression of antiproton clouds in the ALPHA apparatus at CERN
title_full_unstemmed Cold antihydrogen experiments and radial compression of antiproton clouds in the ALPHA apparatus at CERN
title_short Cold antihydrogen experiments and radial compression of antiproton clouds in the ALPHA apparatus at CERN
title_sort cold antihydrogen experiments and radial compression of antiproton clouds in the alpha apparatus at cern
topic Physics in General
url http://cds.cern.ch/record/2284129
work_keys_str_mv AT gutierreza coldantihydrogenexperimentsandradialcompressionofantiprotoncloudsinthealphaapparatusatcern