Measurement of highly charged Ca and Xe ions and their sensitivity to a hypothetical fifth force beyond the Standard Model

It is evident that the current Standard Model of particle physics fails to decode the enigma of dark matter. Amongst dark matter candidates, a promising contender is a hypothetical fifth-force coupling between atom constituents, which is key to establishing a New Physics (NP) model. To prove its existence, isotope shifts are investigated with the King plot method to detect its coupling effect between neutrons and electrons in an atom. Although this effect is weak, it may be resolved with quantum logic spectroscopy of highly charged ions, which offers high precision measurements of isotope shifts, but this method requires ground-state transitions. In this thesis, I measured ground-state transitions in isotope-rich elements, Ca and Xe, using an electron beam ion trap. Furthermore, I theoretically investigated these transitions in their sensitivity to a hypothetical fifth-force, using the generalized King plot method. My results predicted an improvement of sensitivity by at least four orders of magnitude, compared to previous King plot analyses. This sensitivity would constrain the NP parameter space more stringently than prior imposed restrictions. This work lays the theoretical foundation of searching for a fifth force and, ultimately, validating an NP model better suited to decipher our universe's mysteries

Scattering asymmetry in in-situ Mie polarimetry diagnostic of nanodust clouds

Imaging Mie polarimetry is key to determining spatially resolved information about the properties, i.e. refractive index and grain size, of particle clouds, such as during the growth process in reactive particle producing plasmas. Asymmetries in the intensity maps of the different Stokes parameters resulting from the anisotropic scattering of polarized laser light complicate the analysis and require the use of radiative transfer (RT) simulations. We use RT simulations to investigate the asymmetric scattering behavior based on a model of a typical reactive argon-acetylene plasma. We address possible misinterpretations and explore the potential for analyzing particle properties. We find that the asymmetric pattern of the intensity distributions is highly dependent on the refractive index, providing the potential to determine the refractive index and grain size at any time during the growth process

Sensitivity to New Physics of Isotope Shift Studies using the Coronal Lines of Highly Charged Calcium Ions

Promising searches for new physics beyond the current Standard Model (SM) of particle physics are feasible through isotope-shift spectroscopy, which is sensitive to a hypothetical fifth force between the neutrons of the nucleus and the electrons of the shell. Such an interaction would be mediated by a new particle which could in principle be associated with dark matter. In so-called King plots, the mass-scaled frequency shifts of two optical transitions are plotted against each other for a series of isotopes. Subtle deviations from the expected linearity could reveal such a fifth force. Here, we study experimentally and theoretically six transitions in highly charged ions of Ca, an element with five stable isotopes of zero nuclear spin. Some of the transitions are suitable for upcoming high-precision coherent laser spectroscopy and optical clocks. Our results provide a sufficient number of clock transitions for -- in combination with those of singly charged Ca$^+$ -- application of the generalized King plot method. This will allow future high-precision measurements to remove higher-order SM-related nonlinearities and open a new door to yet more sensitive searches for unknown forces and particles.Comment: 8 pages, 4 figure