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The Penning trap mass spectrometer SMILETRAP II and evaporative cooling of highly-charged ions
Stockholm University, Faculty of Science, Department of Physics. (Atomic Physics)
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Accurate mass values have wide-ranging applications in physics and metrology, allowing, for example, to test quantum electrodynamics and fundamental symmetries, to determine fundamental constants, and to establish weight standards.

This thesis describes the new high-precision double-Penning trap mass spectrometer SMILETRAP II which aims at relative uncertainties in the mass determination of 10-10 and below. SMILETRAP II exploits the merits of highly-charged ions as the relative precision in the mass determination with Penning traps is directly proportional to the charge state of the ion. The spectrometer was therefore connected to the electron beam ion trap S-EBIT which is designed to produce bare ions of practically any element up to uranium.

Technical and experimental developments were realized to overcome limitations that restricted the achievable precision at the former spectrometer SMILETRAP I. The technical developments include, for example, an ion detection setup with close to 100% efficiency and an extremely stable temperature-regulation system. Temperature fluctuations constitute a main limitation for the attainable precision.

Cold ions are a prerequisite to reach high precision in experiments with Penning traps. This makes cooling of the ions from the ion sources necessary. Ion temperature measurement and cooling experiments were performed. The transverse temperature of the trapped ions was determined via the emittance of extracted ions. A pepperpot emittance meter was designed to meet the requirements of low-energy, low-intensity beams. To measure the axial temperature and assess the ions’ longitudinal phase-space density, a coherent extraction method was developed. The evaporative cooling technique was successfully implemented. In particular, evaporative cooling of highly-charged ions in a Penning trap could be observed for the first time.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University , 2011. , 82 p.
Keyword [en]
Penning trap, Precision mass spectrometry, Atomic mass, Highly-charged ions, Evaporative cooling, Coherent oscillation, Ion beam emittance
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
URN: urn:nbn:se:su:diva-57787ISBN: 978-91-7447-317-9 (print)OAI: oai:DiVA.org:su-57787DiVA: diva2:418073
Public defence
2011-06-17, FA32, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Epub ahead of print. Paper 6: Accepted. Available from: 2011-05-26 Created: 2011-05-19 Last updated: 2011-05-20Bibliographically approved
List of papers
1. SMILETRAP II
Open this publication in new window or tab >>SMILETRAP II
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2011 (English)In: Hyperfine Interactions, ISSN 0304-3843, E-ISSN 1572-9540, Vol. 199, no 1-3, 141-150 p.Article in journal (Refereed) Published
Abstract [en]

The new Penning trap mass spectrometer SMILETRAP II has been set up at the AlbaNova Research Center, Stockholm. Based on the former spectrometer SMILETRAP I, it uses the merits of highly-charged ions to achieve high precision in the mass measurements. Various improvements over the SMILETRAP I setup will allow to routinely perform mass measurements with relative uncertainties of 10−10 and below. In this paper we will discuss the limitations of SMILETRAP I and present the corresponding improvements of SMILETRAP II. An overview on the SMILETRAP II setup is given.

Place, publisher, year, edition, pages
Springer Netherlands, 2011
Keyword
Atomic masses, Penning trap, Highly-charged ions
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-57629 (URN)10.1007/s10751-011-0308-6 (DOI)
Available from: 2011-05-13 Created: 2011-05-13 Last updated: 2017-12-11Bibliographically approved
2. Improved temperature regulation of Penning trap mass spectrometers
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2010 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 294, no 1, 28-32 p.Article in journal (Refereed) Published
Abstract [en]

In order to reach relative uncertainties in mass measurements with Penning traps of 10-10 or better, the temperature variation of the trap and surrounding materials must be kept below 10 mK. Temperature variations induce a shift in the measured ion cyclotron frequency because of non-zero, temperature dependent magnetic susceptibilities of the construction materials. In this paper we report of a new temperature regulation system recently installed at SMILETRAP II that manages to keep the temperature fixed at the set point with a standard deviation of only 2.6 mK. −10 or better, the temperature variation of the trap and surrounding.

Keyword
Penning trap, Magnetic field, Stabilization, Precision mass spectrometry, Temperature regulation
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-29382 (URN)10.1016/j.ijms.2010.04.008 (DOI)000279462700005 ()
Available from: 2009-08-26 Created: 2009-08-26 Last updated: 2017-12-13Bibliographically approved
3. Evaporative Cooling and Coherent Axial Oscillations of Highly Charged Ions in a Penning Trap
Open this publication in new window or tab >>Evaporative Cooling and Coherent Axial Oscillations of Highly Charged Ions in a Penning Trap
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2011 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 106, no 1, 013002- p.Article in journal (Refereed) Published
Abstract [en]

Externally, in an electron beam ion trap, generated Ar16+ ions were retrapped in a Penning trap and evaporatively cooled in their axial motion. The cooling was observed by a novel extraction technique based on the excitation of a coherent axial oscillation which yields short ion bunches of well-defined energies. The initial temperature of the ion cloud was decreased by a factor of more than 140 within 1 s, while the phase-space density of the coldest extracted ion pulses was increased by a factor of up to about 9.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:su:diva-56739 (URN)10.1103/PhysRevLett.106.013002 (DOI)000286749900008 ()
Available from: 2011-04-27 Created: 2011-04-26 Last updated: 2017-12-11Bibliographically approved
4. Optimization of the Stockholm R-EBIT for the production and extraction of highly charged ions
Open this publication in new window or tab >>Optimization of the Stockholm R-EBIT for the production and extraction of highly charged ions
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2010 (English)In: Journal of Instrumentation, ISSN 1748-0221, Vol. 5, no C11003Article in journal (Refereed) Published
Abstract [en]

We describe a refrigerated EBIT (R-EBIT) commissioned at the AlbaNova Research Center at Stockholm University. As an innovative solution, the superconducting magnet and the trapping drift tubes of the R-EBIT are cooled to a temperature of 4 K by a set of two cooling heads connected to helium compressors. This dry, i.e. liquid helium and liquid nitrogen free, system is easily operated and creates highly charged ions at a fraction of the cost of traditional liquid-cooled systems. A pulsed and continuous gas injection system was developed to feed neutral particles into the electron beam in the trap region. This improves significantly the highly charged ion production and R-EBIT performance. Fast extraction of ions from the R-EBIT yields very short ( < 100 ns), charge-separated ion bunches which can be either analysed using a straight time-of-flight section or sent to experimental beam lines following selection in a bending magnet. An emittance meter was used to measure the emittance of the ions extracted from the R-EBIT. The extracted ions were also re-trapped in a cylindrical Penning trap and properties of the re-trapped ions have been measured using the emittance meter. Results of these measurements are reported in this publication.

National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-57785 (URN)10.1088/1748-0221/5/11/C11003 (DOI)
Available from: 2011-05-19 Created: 2011-05-19 Last updated: 2011-05-20Bibliographically approved
5. The new Stockholm Electron Beam Ion Trap (S-EBIT)
Open this publication in new window or tab >>The new Stockholm Electron Beam Ion Trap (S-EBIT)
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2010 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 5, C12018- p.Article in journal (Refereed) Published
Abstract [en]

A new laboratory for highly charged ions is being built up at Stockholm University. A fully refrigerated electron beam ion trap (R-EBIT, 3 T magnet, 30 keV electron energy) was installed. It was used for spectroscopic studies, ion cooling experiments, electron ion collisions, and highly-charged ion surface studies. Here we report on an upgrade of this EBIT to a ``Super EBIT'' (S-EBIT, 4 T magnet, 260 keV electron energy). The high-voltage trapping system, the ion injection as well as the extraction scheme of S-EBIT and the LabView based operational system of S-EBIT are described.

National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-57786 (URN)10.1088/1748-0221/5/12/C12018 (DOI)
Conference
International Symposium on Electron Beam Ion Sources and Traps (EBIST), Stockholm University, April 7th - 10th, 2010
Available from: 2011-05-19 Created: 2011-05-19 Last updated: 2017-12-11Bibliographically approved
6. A compact time-resolving pepperpot emittance meter for low energy highly-charged ions
Open this publication in new window or tab >>A compact time-resolving pepperpot emittance meter for low energy highly-charged ions
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(English)In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896Article in journal (Refereed) Accepted
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-56741 (URN)
Available from: 2011-04-27 Created: 2011-04-26 Last updated: 2017-12-11Bibliographically approved

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