The successful proposal of Dionysis Antypas aims to create a novel platform for fundamental tests in nuclear and particle physics based on detecting isotopic variation of parity violation in atomic nuclei. The European Research Council (ERC) will support the new project "YbFUN" - where Yb stands for the rare earth metal ytterbium - with an ERC Starting Grant worth EUR 1.46 million. "YbFUN" will run for the next five years at Johannes Gutenberg University Mainz (JGU) in Germany.
For decades, physics assumed that the laws of nature in our world and in the mirror world would be identical, that parity would be preserved. Then in the late 1950s, in the realm of elementary particles, or more precisely in the realm of the weak interaction, researchers discovered a violation of this principle. Parity violation has been a subject of scientific research ever since. Physicists at the PRISMA+ Cluster of Excellence at JGU and the Helmholtz Institute Mainz (HIM) particularly focus on the parity violation of ytterbium atoms with different numbers of neutrons in the nucleus - i.e. different isotopes of this element.
In 2018 they achieved a great success, as Dionysis Antypas describes: "We selected a chain of four of ytterbium's seven isotopes and confirmed the predictions of the Standard Model: the more neutrons in the nucleus, the greater the parity violation effect." The physicists conducted the research using an apparatus at HIM: in the presence of an electric and a magnetic field, ytterbium atoms are excited by laser light and the amplitude of the parity violation is measured.
New method provides a window into the effects of weak interaction in atoms
The promising results - at that time published in the renowned Nature Physics journal - motivated Dionysis Antypas to pursue the project as described in the actual proposal: "We will significantly expand the existing approaches to study isotope-dependent APV variation. This way we want to establish the method as a powerful tool at the interdisciplinary junction between atomic, nuclear and particle physics in order to make measurements of the atomic effects of the weak interaction with unprecedented accuracy. Such a platform would be complementary to high-energy physics experiments in large facilities".
More specifically, comparing the APV effect in different isotopes of the same atomic species is a sensitive tool to study the distribution of neutrons in the nucleus, which in turn is closely related to the structure and size of neutron stars. Indeed, neutron-rich nuclear matter appearing in vastly different sizes, such as the Yb nucleus (of size ?1 femtometer, or 10-15 meter) and a neutron star (of size ?10 kilometer), is described by the same physics models.
As part of their earlier measurements the researchers have also provided information on an additional Z-boson. Z bosons mediate the weak interaction and scientists in the field speculate the existence of a further Z boson, referred to as the "Z prime" or "Z'" with a much smaller mass than that of the established Z boson. For that reason, the new platform to be established in the context of "YbFUN" is also a probe of additional vector bosons, beyond the Standard Model of particle physics. Finally, the study of nuclear-spin-dependent contributions to the APV effect in isotopes with nuclear spin is a sensitive way to investigate intranuclear weak interactions, which are currently poorly understood.
Dr. Dionysis Antypas was born in 1981 in Kefalonia, Greece. He studied Physics at the Aristotle University of Thessaloniki and obtained a PhD in Physics from Purdue University, USA in 2013. Following his PhD he joined in 2014 the group of Prof. Dr. D. Budker within the Matter-Antimatter section at the Helmholtz Institute Mainz, where as a postdoc, he focused on carrying out preliminary studies of parity violation in Yb. Using the ERC Starting Grant, he also plans to set up a work group.
An ERC Starting Grant is one of the most richly endowed EU funding awards for young researchers. ERC Starting Grants are designed to support outstanding researchers at the beginning of their careers while they form their own research team or establish their research program. In order to receive the grant, applicants must not only demonstrate excellence in research, but also provide evidence of the pioneering nature of their project and its feasibility.