Atomic parity violation in a single radium ion

PhD ceremony: Ms. L.W. Wansbeek, 16.15 uur, Aula Academiegebouw, Broerstraat 5, Groningen

Dissertation: Atomic parity violation in a single radium ion

Promotor(s): prof. R.G.E. Timmermans and prof. K. Jungmann

Faculty: Mathematics and Natural Sciences

The thesis of Lotje Wansbeek is about a low-energy precision test of the Standard Model (SM) of particle physics. More specifically, about how a single, trapped radium ion is a promising candidate for an Atomic Parity Violation (APV) experiment. The ultimate goal of such an experiment is to extract the weak charge of radium, and consequently, a low-energy (in the order 1 MeV) value for the Weinberg angle. Since the SM makes an accurate prediction for this value, an APV experiment constitutes a low-energy test of the SM. A difference between the SM and experiment could be a sign of new physics.

In her thesis, a number of subjects related to an APV experiment in a radium ion are treated by Wansbeek. First, the sensitivity of an APV experiment to new physics is briefly studied. APV is especially sensitive to the additional Z bosons that appear in many successors of the SM.  The size of the APV effect in the radium ion is calculated, and found to be 50 times larger than the effect in the cesium atom, for which the most accurate APV experiment to date has been performed. It is confirmed that certain transitions in the radium ion are interesting candidates for an all-optical atomic clock. Especially interesting is the high intrinsic sensitivity of these transitions to temporal variation of the fine structure constant. Finally, experimentally determined isotope shifts are used to study the shape of the radium nucleus.