Inside the Unilateral Accelerator

Physicists harnessed Germany’s UNILAC accelerator to make nobelium atoms for structural analysis. Credit: Nicolas Armer/picture alliance/dpa

Nuclear physics

First glimpse of a giant nucleus reveals its peculiar shape

Lasers offer insight into the heaviest elements.

A record-setting observation has determined the structure of an atom of nobelium, the heaviest element to be observed in such detail.

Elements with atomic numbers greater than 100 decay quickly, making them difficult to observe. A team led by Sebastian Raeder at the GSI Helmholtz Center for Heavy Ion Research in Darmstadt, Germany, trained a laser on isotopes of nobelium, which has 102 protons. As the researchers varied the laser’s frequency, they measured the number of atoms that were ionized, or stripped of an electron.

This method allowed the scientists to deduce the radius and other properties of the nucleus. The researchers found that unlike smaller nuclei, which tend to be spherical, the nobelium nucleus is shaped like a rugby ball or an American football.

The results could furnish physicists with clues about the ‘island of stability’ — a predicted class of superheavy elements that are expected to be much more stable and longer-lasting than most of their heavy brethren.