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@PHDTHESIS{Rosenthal:671012,
author = {Rosenthal, Marcel},
othercontributors = {Pretz, Jörg and Lehrach, Andreas and Aulenbacher, Kurt},
title = {{E}xperimental benchmarking of spin tracking algorithms for
electric dipole moment searches at the cooler synchrotron
{COSY}},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
reportid = {RWTH-2016-07944},
pages = {1 Online-Ressource (XI, 170, xxv Seiten) : Illustrationen,
Diagramme},
year = {2016},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2016},
abstract = {Known CP violating sources in the Standard Model of
Particle Physics are not sufficient to explain the
predominance of the observed matter in the Universe.
Additional sources beyond the Standard Model are required.
These sources can manifest in permanent electric dipole
moments (EDMs) of elementary particles. Searches for neutral
particles already started decades ago, but no value
significantly different from zero has been observed. The
current upper limit for the neutron amounts to 2.9 ·
$10^−26$ e cm $(90\%$ C. L.). New measurement methods for
protons and deuterons in dedicated electrostatic storage
rings are proposed. As an intermediate step, essential
requirements and limitations are studied by the JEDI
(Jülich Electric Dipole moments Investigations)
collaboration at the existing magnetic storage ring, the
Cooler Synchrotron COSY. A first direct measurement of the
deuteron EDM is planned, which employs a radiofrequency (RF)
Wien filter to create an EDM related spin polarization
signal. In the scope of this thesis a new framework
providing a convenient environment for simulation and
analysis was created to model this new method. It interfaces
with the existing simulation code COSY INFINITY to calculate
transfer maps for the particle beam and spin coordinates.
These maps are used to perform repetitive tracking. New
transfer map based algorithms have been implemented to
extend the functionality for time-varying electromagnetic
fields. One of the major requirements for storage ring based
EDM searches is a long spin coherence time, which limits the
available time to conduct the measurement. Important
contributions to spin decoherence arising from
path-lengthening of individual particles and from intrinsic
spin resonances have been discussed and verified by
simulation studies. To cancel those contributions, storage
ring parameters like betatron tunes, chromaticities and
momentum compaction factors require precise adjustment. The
measured locations of longest spin coherence times confirmed
the model predictions for different betatron tunes. Based on
a conservative definition, spin coherence times of about 750
s have been achieved during these studies at COSY. The long
spin coherence time allowed for the benchmarking of the new
algorithms for time-varying fields. An existing RF solenoid
running on an artificial spin resonance was used to
introduce vertical polarization oscillations. Theoretical
calculations predict a dependence of the oscillation
amplitude on the solenoid frequency. These calculations were
successfully verified by simulations and measurements. Also
analytical estimates of the EDM related polarization could
be confirmed by the new algorithms. Systematic contributions
mimicking this signal arise from misalignments and field
imperfections of the RF Wien filter or the storage ring
magnets. Calculations predicted that an RF Wien filter
rotation about the longitudinal axis by 0.1 mrad produces a
similar signal as an EDM 5 · $10^−19$ e cm. The same
order of magnitude was obtained by randomly shifting the
quadrupole magnets in vertical direction assuming a Gaussian
distribution with a width of 0.1 mm. Finally, orbit
correction methods to suppress these systematic
contributions were applied in simulations. These partially
compensated the false EDM signal contributions from
misalignments of the static storage ring elements.},
cin = {134820 / 130000 / 139520},
ddc = {530},
cid = {$I:(DE-82)134820_20140620$ / $I:(DE-82)130000_20140620$ /
$I:(DE-82)139520_20140620$},
typ = {PUB:(DE-HGF)11},
urn = {urn:nbn:de:hbz:82-rwth-2016-079449},
url = {https://publications.rwth-aachen.de/record/671012},
}
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