The Penning trap mass spectrometer SMILETRAP II and evaporative cooling of highly-charged ions
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
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.
Penning trap, Precision mass spectrometry, Atomic mass, Highly-charged ions, Evaporative cooling, Coherent oscillation, Ion beam emittance
Atom and Molecular Physics and Optics
Research subject Physics
IdentifiersURN: urn:nbn:se:su:diva-57787ISBN: 978-91-7447-317-9OAI: oai:DiVA.org:su-57787DiVA: diva2:418073
2011-06-17, FA32, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Lunney, David, Professor
Schuch, Reinhold, Professor
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.
List of papers