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Improved temperature regulation of Penning trap mass spectrometers
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
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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.

Place, publisher, year, edition, pages
2010. Vol. 294, no 1, 28-32 p.
Keyword [en]
Penning trap, Magnetic field, Stabilization, Precision mass spectrometry, Temperature regulation
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
URN: urn:nbn:se:su:diva-29382DOI: 10.1016/j.ijms.2010.04.008ISI: 000279462700005OAI: oai:DiVA.org:su-29382DiVA: diva2:232786
Available from: 2009-08-26 Created: 2009-08-26 Last updated: 2017-12-13Bibliographically approved
In thesis
1. SMILETRAP I / II: Precision Improvements in Penning-Trap Mass-Spectrometry
Open this publication in new window or tab >>SMILETRAP I / II: Precision Improvements in Penning-Trap Mass-Spectrometry
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes the final precision mass measurements with SMILETRAP I, where a relative precision of < 1 ppb (10-9) was reached routinely, and the development of SMILETRAP II, aiming for measurements with < 0.1 ppb relative precision. The emphasis of the thesis is on the implementation of new techniques for achieving this precision improvement with SMILETRAP II. The Ramsey multiple-pulse excitation technique was tested at SMILETRAP I, and a reduction of the statistical uncertainty by factor three could by verified. The technique was applied in the last measurement with SMILETRAP I on H2+ and D+ ions. From these measurements the proton mass was deduced with a relative error of 0.18 ppb. It was found that temperature dependent magnetic field oscillations limited us from reducing the uncertainties further. A technical achievement of reducing the peak to peak temperature oscillation in the trapping region of SMILETRAP II by a factor four is presented, which should give an extended observation time and likewise improved precision. The new SMILETRAP II super-conducting magnet, with a slightly stronger field of 5.8 T compared with the previous of 4.7 T, was installed and adjusted.  A careful field alignment and reduction of inhomogeneities was done for minimizing the disturbances of the cyclotron frequency for improved precision. In that attempt, the localization and control of the trapped ion motion is also important. Thus a new cooling trap was set up. In the spring of 2009 coherent axial motion of a confined ion cloud was discovered in the cooling trap. By observation of the axial oscillations we can see the effects of evaporative cooling in the reduction of the axial energy distribution. Storing the ions up to 1 s in the cooling trap reduces the energy distribution by a factor of five. Other remarkable results of the ion oscillations are also reported.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2009. 78 p.
Keyword
Penning trap, Mass spectrometers, Instrumentation and methods for time-of-flight (TOF) spectroscopy, Highly charged ions
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-29399 (URN)978-91-7155-931-9 (ISBN)
Public defence
2009-09-25, sal FA31, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: In progress. Paper 3: Submitted.Available from: 2009-09-03 Created: 2009-08-26 Last updated: 2010-01-13Bibliographically approved
2. Precision mass measurements: Final limit of SMILETRAP I and the developments of SMILETRAP II
Open this publication in new window or tab >>Precision mass measurements: Final limit of SMILETRAP I and the developments of SMILETRAP II
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The subject of this thesis is high-precision mass-measurements performed with Penning trap mass spectrometers (PTMS). In particular it describes the SMILETRAP I PTMS and the final results obtained with it, the masses of 40Ca and that of the proton. The mass of 40Ca is an indispensible input in the evaluation of measurements of the bound electron g-factor, used to test quantum electrodynamical calculations in strong fields. The value obtained agrees with available literature values but has a ten times higher precision.

The measurement of the proton mass, considered a fundamental physical constant, was performed with the aim of validating other Penning trap results and to test the limit of SMILETRAP I. It was also anticipated that a measurement at a relative precision close to 10-10 would give insight in how to treat certain systematic uncertainties. The result is a value of the proton mass in agreement with earlier measurements and with an unprecedented precision of 1.8×10-10.

Vital for the achieved precision of the proton mass measurement was the use of the Ramsey excitation technique. This technique, how it was implemented at SMILETRAP I and the benefits from it is discussed in the thesis and in one of the included papers.

The second part of the thesis describes the improved SMILETRAP II setup at the S-EBIT laboratory, AlbaNova. All major changes and upgrades compared to SMILETRAP I are discussed. This includes, apart from the Ramsey excitation technique, higher ionic charge states, improved temperature stabilization, longer run times, different reference ions, stronger and more stable magnetic field and a more efficient ion detection. Altogether these changes should reduce the uncertainty in future mass determinations by an order of magnitude, possibly down to 10-11.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2011. 64 p.
Keyword
SMILETRAP, Precision mass spectrometry, Penning trap, Atomic mass, Highly charged ions, Low energy ion storage, Time of flight ion cyclotron resonance, High frequency, Proton mass, QED, g-factor
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-56777 (URN)978-91-7447-303-2 (ISBN)
Public defence
2011-05-26, sal FB53, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 9: Accepted.Available from: 2011-05-04 Created: 2011-04-27 Last updated: 2011-05-13Bibliographically approved
3. The Penning trap mass spectrometer SMILETRAP II and evaporative cooling of highly-charged ions
Open this publication in new window or tab >>The Penning trap mass spectrometer SMILETRAP II and evaporative cooling of highly-charged ions
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
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:nbn:se:su:diva-57787 (URN)978-91-7447-317-9 (ISBN)
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

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Hobein, MatthiasSolders, AndreasSuhonen, MarkusSchuch, Reinhold
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