Pear-shaped atomic nuclei at the top 10 of break-throughs in physics

Pear-shaped atomic nuclei can reveal clues as to why the Universe is made up of more matter than anti-matter. Professor of Physics Joakim Cederkäll’s research on this type of atomic nucleus has now made it onto the top 10 of breakthroughs in physics from 2013.

Joakim Cederkall

Professor of Physics Joakim Cederkäll talks about the hunt for answers to the mystery of matter and anti-matter. Photo: Gunnar Menander.

Professor of Physics Joakim Cederkäll talks about the hunt for answers to the mystery of matter and anti-matter. Photo: Gunnar Menander.

According to the theory of the origins of the Universe, matter was created from energy in the Big Bang, in line with Einstein’s famous realisation that matter and energy are two sides of the same coin. In the processes that are currently known, however, every particle of matter created in this way in the laboratory is accompanied by a particle of anti-matter. However, if the same thing happened in the Big Bang, i.e. the creation of an equal amount of matter and anti-matter, after a while the particles and anti-particles would have wiped one another out and nothing of substance would be left. Our world would not exist. The question is what did happen.

“There must be something that made the matter win over the anti-matter. At the moment, we have no evidence for any theory that explains why there was such a big difference between matter and anti-matter. There are explanations for smaller differences, but not as large as those we can observe”, said Professor Joakim Cederkäll from the Department of Physics.

For many years, he has studied various properties of atomic nuclei through experiments at the CERN particle accelerator near Geneva. Last year, he and his colleagues produced research results that suggest there are atomic nuclei that are pear-shaped. Normal atomic nuclei are shaped more like a rugby ball or are spherical like a football. In the pear-shaped nuclei, the mass of the nucleus is shifted slightly towards one end of the nucleus. It is this shift that interests researchers.

“Many research groups around the world are looking for something called EDM, the electrical dipole moment”, says Joakim Cederkäll.

The electrical dipole moment could play a key role in the hunt for clues to the essence of anti-matter. Joakim Cederkäll explains that a number of groups worldwide are looking for EDM at particle level because it could mean that certain basic symmetries are broken in nature, which in turn could explain how the Universe came to be dominated by matter.

“Our findings point out which atoms are especially suitable to study in the hunt for EDM, especially using methods from atomic physics. They thus complement the research being carried out in the large experiments at CERN”, says Joakim Cederkäll.

Last year, their research findings were featured on the cover of the journal Nature. A while ago, they made it onto Physics World’s top ten of research breakthroughs in physics in 2013.

“It is particularly pleasing that the award went to the entire research team. This type of research cannot be performed by one individual; it requires a team of capable and enthusiastic researchers who choose to collaborate on a shared interest”, says Joakim Cederkäll.

Lena Björk Blixt