Presented by: Lars von der Wense, Johannes Gutenberg University Mainz

Abstract: The year 2024 was a breakthrough year in ²²⁹Th-related research, with three experiments reporting success in the laser spectroscopy of the lowest nuclear excited state of ²²⁹Th. The highest accuracy was achieved at JILA via direct frequency comb spectroscopy of this, previously elusive, nuclear state. This success is the result of several decades of effort to precisely determine the transition energy and a first step towards nuclear precision spectroscopy and the development of a nuclear frequency standard of extremely high accuracy. Applications for dark matter detection as well as the search for time variations of fundamental constants appear to be in reach.
In this talk I will provide an overview over the history of ²²⁹Th that has culminated in this success. Further, I will discuss the remaining efforts and challenges. Finally, I will introduce the investigations underway within the framework of the BMFTR-funded project “NuQuant”.

Host: Ethan Neil