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Preparation and Investigation of Highly Charged Ions in a Penning Trap for the Determination of Atomic Magnetic Moments

Wiesel, Marco :
Preparation and Investigation of Highly Charged Ions in a Penning Trap for the Determination of Atomic Magnetic Moments.
[Online-Edition: http://tuprints.ulb.tu-darmstadt.de/6280]
Technische Universität , Darmstadt
[Dissertation], (2017)

Offizielle URL: http://tuprints.ulb.tu-darmstadt.de/6280

Kurzbeschreibung (Abstract)

The ARTEMIS experiment aims at measuring magnetic moments of electrons bound in highly charged ions that are stored in a Penning trap. It will provide access to effects of quantum electrodynamics (QED) in the extreme fields close to an ionic nucleus. Additionally, due to the high magnetic field of the Penning trap, higher-order Zeeman effects can be examined and therefore provide a different access to the theory of QED. In this work, a cooled cloud of boron-like argon ions, Ar13+, was prepared in the creation part of a double Penning trap held at cryogenic temperatures. Systematic measurements were carried out in order to investigate the creation trap and its specific parameters to generate a suitable ion cloud. This ion cloud consisted after further charge breeding of different charge states. It was then cooled and parts of it were excited by the SWIFT-technique and, in combination with fast potential-switching, all ion species except Ar13+ were removed. Together with the successful transport of an ion cloud from the creation trap into the spectroscopy trap all concepts necessary in order to prepare an Ar13+ ion cloud for performing laser microwave double-resonance spectroscopy have been implemented. Additionally, a measurement of the modified cyclotron frequency in the creation trap was carried out by exciting the ions radially while detecting their axial motional frequency. Thus, a value for the magnetic field strength in the creation trap with a 5 parts-per-million accuracy was achieved. A system for irradiating microwaves with a frequency of 65 gigahertz onto the position of the ions was developed, characterized and implemented into the apparatus. It was conceptualized for meeting the challenging conditions of the experiment, such as the high magnetic field, the cryogenic temperatures and the difficult geometry. A novel concept of employing an indium tin oxide (ITO)-coated window as an endcap for a closed Penning trap was implemented in the spectroscopy trap and its functionality was proven. The window improves the fluorescence photon efficiency by at least 17% and increases the planarity over the previously used mesh and therefore decreases the trap anharmonicities. Additionally, a test of the ITO-coated window proved its applicability as a Faraday cup for detecting highly charged ions. During this thesis, experimental studies of the various components of ARTEMIS have been carried out and the full apparatus was assembled and put into operation. The focus of this work was the design of the mechanical parts and their assembly, such as the cryogenic concept and the vibrational decoupling. In the future, ARTEMIS will be connected to the HITRAP beamline at GSI, so heaviest highly charged ions can be examined. During this work, a fast opening valve, that separates the trap vacuum from the beamline vacuum, was assembled and initial tests were conducted.

Typ des Eintrags: Dissertation
Erschienen: 2017
Autor(en): Wiesel, Marco
Titel: Preparation and Investigation of Highly Charged Ions in a Penning Trap for the Determination of Atomic Magnetic Moments
Sprache: Englisch
Kurzbeschreibung (Abstract):

The ARTEMIS experiment aims at measuring magnetic moments of electrons bound in highly charged ions that are stored in a Penning trap. It will provide access to effects of quantum electrodynamics (QED) in the extreme fields close to an ionic nucleus. Additionally, due to the high magnetic field of the Penning trap, higher-order Zeeman effects can be examined and therefore provide a different access to the theory of QED. In this work, a cooled cloud of boron-like argon ions, Ar13+, was prepared in the creation part of a double Penning trap held at cryogenic temperatures. Systematic measurements were carried out in order to investigate the creation trap and its specific parameters to generate a suitable ion cloud. This ion cloud consisted after further charge breeding of different charge states. It was then cooled and parts of it were excited by the SWIFT-technique and, in combination with fast potential-switching, all ion species except Ar13+ were removed. Together with the successful transport of an ion cloud from the creation trap into the spectroscopy trap all concepts necessary in order to prepare an Ar13+ ion cloud for performing laser microwave double-resonance spectroscopy have been implemented. Additionally, a measurement of the modified cyclotron frequency in the creation trap was carried out by exciting the ions radially while detecting their axial motional frequency. Thus, a value for the magnetic field strength in the creation trap with a 5 parts-per-million accuracy was achieved. A system for irradiating microwaves with a frequency of 65 gigahertz onto the position of the ions was developed, characterized and implemented into the apparatus. It was conceptualized for meeting the challenging conditions of the experiment, such as the high magnetic field, the cryogenic temperatures and the difficult geometry. A novel concept of employing an indium tin oxide (ITO)-coated window as an endcap for a closed Penning trap was implemented in the spectroscopy trap and its functionality was proven. The window improves the fluorescence photon efficiency by at least 17% and increases the planarity over the previously used mesh and therefore decreases the trap anharmonicities. Additionally, a test of the ITO-coated window proved its applicability as a Faraday cup for detecting highly charged ions. During this thesis, experimental studies of the various components of ARTEMIS have been carried out and the full apparatus was assembled and put into operation. The focus of this work was the design of the mechanical parts and their assembly, such as the cryogenic concept and the vibrational decoupling. In the future, ARTEMIS will be connected to the HITRAP beamline at GSI, so heaviest highly charged ions can be examined. During this work, a fast opening valve, that separates the trap vacuum from the beamline vacuum, was assembled and initial tests were conducted.

Ort: Darmstadt
Fachbereich(e)/-gebiet(e): 05 Fachbereich Physik
05 Fachbereich Physik > Institut für Angewandte Physik > Atome Photonen Quanten
Hinterlegungsdatum: 02 Jul 2017 19:55
Offizielle URL: http://tuprints.ulb.tu-darmstadt.de/6280
URN: urn:nbn:de:tuda-tuprints-62803
Gutachter / Prüfer: Birkl, Prof. Dr. Gerhard ; Quint, PD Dr. Wolfgang
Datum der Begutachtung bzw. der mündlichen Prüfung / Verteidigung / mdl. Prüfung: 24 Mai 2017
Alternatives oder übersetztes Abstract:
AbstractSprache
Das ARTEMIS-Experiment speichert hochgeladene Ionen in einer Penning-Falle und zielt dabei auf die Messung der magnetischen Momente der darin gebundenen Elektronen ab. Dies ermöglicht den Zugang zu den Effekten der Quantenelektrodynamik (QED) unter den extremen Bedingungen in der Nähe des Ionenkerns. Aufgrund des starken magnetischen Feldes der Penning-Falle kann außerdem der Zeeman-Effekt höherer Ordnung untersucht werden, was einen alternativen Zugang zur QED darstellt. Im Rahmen dieser Arbeit wurde eine gekühlte Wolke borähnlicher Argonionen, Ar13+, im Erzeugungsteil einer kroygenen Doppel-Penningfalle präpariert. Es wurden Messungen durchgeführt, um die Erzeugungsfalle und ihre spezifischen Parameter zu untersuchen, sodass eine geeignete Ionenwolke generiert werden konnte. Diese Wolke, welche sich nach dem Ladungsbrüten aus unterschiedlichen Ladungszuständen zusammensetzt, wurde gekühlt und Teile davon mittels der SWIFT-Technik angeregt, um hiernach durch schnelles Schalten des Fallenpotentials alle ungewollten Ionenspezies außer Ar13+ zu enfternen. Gemeinsam mit dem erfolgreichen Transport einer Ionenwolke von der Erzeugungs- in die Spektroskopiefalle wurden damit alle nötigen Konzepte zur Präparation einer Ar13+-Wolke implementiert, um die Laser-Mikrowellen-Doppelresonanzspektroskopie durchzuführen. Außerdem wurde in der Erzeugungsfalle eine Messung der modifizierten Zyklotronfrequenz durch radiale Anregung und Detektion der axialen Bewegungsfrequenz durchgeführt und damit ein Wert für die Magnetfeldstärke mit einer Genauigkeit im ppm-Bereich ermittelt. Um die Ionen mit Mikrowellen mit einer Frequenz von 65 Gigahertz zu bestrahlen, wurde ein Mikrowellensystem entwickelt, charakterisiert und ins Experiment eingebaut. Es galt dabei, die schwierigen Bedingungen des Experiments (starkes Magnetfeld, kryogene Temperaturen und die schwierige Geometrie) zu erfüllen. Ein neues Konzept, das ein indiumzinnoxid (ITO)-beschichtetes Fenster als Endkappe einer geschlossenen Penningfalle nutzt, wurde erfolgreich umgesetzt. Mit diesem Fenster konnte die Fluoreszenzphotoneneffizienz gegenüber des zuvor verwendeten Netzes um 17% gesteigert und durch bessere Planarität die Anharmonizitäten der Falle verringert werden. Zudem wurde das Fenster auch in seiner Tauglichkeit als Farraday-Detektor zur Detektion hochgeladener Ionen getestet. Während dieser Arbeit wurden experimentelle Studien zu den einzelnen Komponenten durchgeführt und schließlich das komplette Experiment zusammengebaut und in Betrieb genommen. Der Schwerpunkt dieser Arbeit lag dabei im Design der mechanischen Komponenten und deren Installation, erwähnt seien hierbei das Konzept der kryotechnischen Umsetzung und die Vibrationsentkopplung. In Zukunft soll das Experiment an die HITRAP-Strahllinie der GSI angebunden werden, um höchstgeladene Ionen untersuchen zu können. Für dieses Ziel wurden im Rahmen dieser Arbeit ein schnellöffnendes Ventil, das das Fallenvakuum vom Stahllinienvakuum trennen soll, zusammengebaut und erste Tests durchgeführt.Deutsch
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