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| Dissertation / PhD Thesis | GSI-2022-00355 |
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2021
RWTH Aachen University
Please use a persistent id in citations: doi:10.18154/RWTH-2021-08453
Abstract: One of the unsolved puzzles of physics is the matter over antimatter dominance in our universe. The required matter-antimatter asymmetry is not explained within the standard model of particle physics and cosmology and current measurements, thus more CP violating effects are needed to explain that discrepancy. One of the possible sources for CP violation is a non-vanishing Electric Dipole Moment (EDM) of elementary particles. So far, all the measurements only provide upper limits and are consistent with a vanishing EDM. The Jülich Electric Dipole moment Investigations (JEDI) collaboration wants to directly measure the EDM of the proton and deuteron, which has not been done so far. This is done in the Cooler Synchrotron (COSY) storage ring with a Radio Frequency (RF) wien filter to observe a buildup of the vertical polarization proportional to the EDM. In addition the Magnetic Dipole Moment (MDM), which is orders of magnitude larger than the EDM, also influences the polarization of the stored beam. It is possible for the MDM to mimic the effect of an EDM in a non perfect machine. In order to eliminate that systematic effect one has to compare simulations to the measured data. To simulate the accelerator it is required to know the exact positions of all elements in the ring with a high precision. Therefore an alignment campaign of the magnets has been done. Unfortunately the Beam Positron Monitors (BPMs), which are essential to know how the beam passes the magnets, could not be aligned with that campaign. Thus a dedicated method to align the BPMs was developed and implemented to measure their alignment. The chosen method is the beam-based alignment method, which is aligning the BPMs with respect to the quadrupole magnetic centers and thus also within the coordinate system of all the magnets. The beam-based alignment measurements show a shift of the BPMs of up to 5 mm with respect to their ideal position, which has been corrected for. In addition, now the correction of the orbit to the optimal position (zero) is better and needs less steering magnets, as one does not have to steer against the beam passing off-center inside the quadruopoles anymore.
Keyword(s): COSY ; EDM ; accelerator ; alignment ; quadrupole
Note: Dissertation, RWTH Aachen University, 2021
Contributing Institute(s): Research Program(s): Experiment(s):
Appears in the scientific report 2021
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