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UBC Theses and Dissertations

Integration of a multi reflection time of flight isobar separator into the TITAN experiment at TRIUMF Finlay, Andrew

Abstract

The TITAN experiment at TRIUMF performs high-precision mass measurements on rare isotopes using Penning trap mass spectrometry. A major challenge is the presence of isobaric contamination introduced by the rare isotope production process. To remove these a new Multi-Reflection Time-of-Flight (MR-ToF) mass spectrometer and isobar separator has been integrated into the TITAN system. To facilitate the integration of the MR-ToF the TITAN beamline has been studied using a combination of computer based ion optics simulations and experimental measurements. Simulations were benchmarked against a measurement of the ion beam’s transverse emittance using an Allison meter, and beam time profiles measured with microchannel plate detectors. Computer models were found to be able to reproduce experimental results within a factor of 2. The key source of differences appears to be the modeling of the cooler buncher TITAN uses for beam preparation. Simulations were used to identify optimal settings on ion optical elements to facilitate the maximum efficiency of ion transport into the MR-ToF and from the MR-ToF to the measurement Penning trap. Additional tests of the impact of new optics on the beamline when bypassing the MR-ToF show beam properties before and after the changes to be identical within uncertainty. Suggested settings have successfully been used to guide the injection of ions into the MR-ToF. Once the MR-ToF was installed in the TITAN system, tests were performed to demonstrate the functionality of the MR-ToF using externally produced beam. The ISAC Off-Line Ions Source was used to produce a ⁴⁰Ar⁺ ion beam for testing. This was merged with ⁴⁰K⁺ ions from the MR-ToF internal ion source to demonstrate the resolving power of the MR-ToF. Mass measurements were performed at a resolving power of 200 000, exceeding performance expectations by a factor of 2. Isobar separation was used to remove either Ar or K, requiring a mass resolving power ≥ 25 000. The MR-ToF is now a functioning part of the

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