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Simulations of the image charge effect in high-precision Penning traps and the new IGISOL ion buncher

Schuh, Marc

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Abstract

Penning traps are currently the most precise mass measurement devices resulting from a long development, which started around 1900. With a relative precision of up to E−12 , Penning traps allow testing of various physical theories by means of mass measurements, such as quantum electrodynamics (QED), the CPT (charge, parity and time) theorem and theory of special relativity. In order to achieve this precision, many devices have to be coordinated and measurements have to be performed repeatedly. This work presents the basic structure of a newly-developed Python based control system for the THe-Trap experiment at the Max-Planck-Institute for Nuclear Physics in Heidelberg, Germany. During the development the focus was placed on enabling the user to recognize the state of the experiment at just one glance. It is also possible to control and automate the experiment with external scripts based on Python as well. High-precision Penning trap experiments worldwide with the above-mentioned precision are limited among other things by the so-called image charge effect. This effect is caused by the image charges induced by the ion in the surrounding electrodes of the Penning trap. These image charges generate an additional electric field, which systematically shifts the frequency of the ion and thus the measurement result. This thesis presents a numerical calculation of the image charge effect for various experiments using the finite element method in COMSOL multiphysicsTM. The results of the simulation have an uncertainty of 1 % and agree with the measurement results, which have an uncertainty of about 5 %. Time-of-flight measurements show their strength in determining the mass of short-lived nuclides with a half-life of less than 100 ms. Ions are reflected several times to extend the flight distance, which has given the instruments the name multi-reflection time-of-flight mass spectrometer (MR-ToF MS). They also serve as fast mass separators. However, MR-Tof MS require ion pulses with a temporal width of about 100 ns or shorter. In this work, an ion buncher using SIMION was developed, built, and tested for the IGISOL experiment in Jyväskylä, Finland. During the test a pulse width of 107 ns could be achieved.

Item Type: Dissertation
Supervisor: Blaum, Prof. Dr. Klaus
Date of thesis defense: 23 May 2019
Date Deposited: 29 May 2019 06:38
Date: 2019
Faculties / Institutes: The Faculty of Physics and Astronomy > Institute of Physics
Subjects: 530 Physics
Controlled Keywords: Penning Trap, Mass spectrometry, FEM, Python
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