Dissertation / PhD Thesis

GSI-2025-00337

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Investigation of systematic effects and uncertainties involved in the determination of the invariant spin axis in a storage ring for an EDM measurement

Vitz, M. ; Pretz, J. (Supervisor) ; Stahl, A. (Supervisor)

2024
RWTH Aachen University

Please use a persistent id in citations: doi:10.18154/RWTH-2024-11202

Abstract: The excess of matter over antimatter in the known part of the Universe cannot be explained by the Standard Model of particle physics. Mechanisms that violate CP symmetry exist in the Standard Model and can be used to explain the excess of matter over antimatter. However, they are too weak to account for the observed asymmetry. Therefore, additional sources of CP violation are being investigated. A promising candidate for further CP violation beyond those established in the Standard Model is the permanent electric dipole moment of elementary particles. Using storage rings as particle traps, the EDM of charged particles can be studied, since the orientation of the polarization rotation axis also called the invariant spin axis is determined by the EDM.Therefore, the JEDI collaboration at Jülich has carried out the first direct EDM measurement of deuterons with the Precursor Runs at the storage ring COSY. Using solenoids and an RF Wien filter, the invariant spin axis tilt angle was determined. In addition to the influence of the EDM, the ISA tilt angle is also influenced by the storage ring systematics. Therefore, particle and spin tracking simulations in an accurate simulation model of the COSY storage ring are required to disentangle a potential EDM signal from the storage ring systematics. This thesis presents the development of such a simulation model of the COSY storage ring, based on the BMAD software library, in order to investigate the systematic effects, present during the Precursor Run 2 in 2021. Correction factors depending on the measurement method are shown and the uncertainties of the systematic effects and the COSY orbit measurements are discussed. Finally, it is shown that the measured ISA tilt angles at the RF Wien filter obtained during Precursor Run 2 are too large to originate from storage ring systematics in COSY or a potential EDM.

Keyword(s): Hochschulschrift

Note: Dissertation, RWTH Aachen, 2024

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Contributing Institute(s):

1. FAIR Forschung NRW (FFN)

Research Program(s):

1. 612 - Cosmic Matter in the Laboratory (POF4-612) (POF4-612)

Experiment(s):

1. External experiment at external facility/ no experiment at GSI (other)

Appears in the scientific report 2024

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