The journey of a nuclear physicist to a mythical island

Theories about the possible existence of superheavy elements were introduced back in the 1960s. Their longest-lived nuclei could cause a so-called “island of stability” far beyond the uranium element. However, a new study conducted by nuclear physicists at Lund University shows that the 50-year-old manifesto of nuclear physics now needs to be revised.

The heaviest element found in nature is uranium, whose nucleus contains 92 protons and 146 neutrons. The nuclei of heavier elements are becoming increasingly unstable due to an increase in the number of positively charged protons. So they fall apart faster and faster, usually within a split second.

However, the “magic” combination of protons and neutrons can lead to elements with rapidly increasing lifespans. It is this “magic” number of protons has long been predicted for the element Fleury, which has an atomic number of 114 in the periodic table. In the late 1960s, Lund physicist Sven-Gosta Nilsson, among others, theorized that such an island of stability should exist around an as yet undiscovered element 114.

“It’s kind of like the Holy Grail in nuclear physics. Many people dream of discovering something as exotic as a long-lived or even stable superheavy element, ”said Anton Samark-Roth, a doctoral student in nuclear physics at Lund University.

Inspired by Nielson’s theories, the researchers studied the element of flair in detail and made groundbreaking discoveries. The experiment was conducted by an international research group led by Dirk Rudolf, a professor at Lund University.

As part of the FAIR Phase-0 research program at the GSI Helmholtzzentrum für Schwerionenforschung particle accelerator in Darmstadt, Germany, up to 6 × 10¹⁸ (6,000,000,000,000,000,000,000) The nuclear nuclei of calcium-48 were accelerated to 10 percent of the speed of light. They bombarded a thin film of rare plutonium-244, and with the help of nuclear fusion it was possible to create flair.[{” attribute=””>atom at a time. In the 18-day-long experiment, the research team then registered radioactive decay of some tens of flerovium nuclei in a detection device specially developed in Lund.

Through the exact analysis of decay fragments and the periods within which they were released, the team could identify new decay branches of flerovium. It was shown that these could not be reconciled with the element’s previously predicted “magical” properties.

“We were very pleased that all the technology surrounding our experimental set-up worked as it should when the experiment started. Above all, being able to follow the decay of several flerovium nuclei from the control room in real time was very exciting,” says Daniel Cox, postdoc in nuclear physics at Lund University.

The new results, published in the research journal Physical Review Letters, will be of considerable use to science. Instead of looking for the island of stability around the element 114, the research world can focus on other as yet undiscovered elements.

“It was a demanding but, of course, very successful experiment. Now we know, we can move on from element 114 and instead look around element 120, which has not been discovered yet. Now the voyage to the island of stability will take a new course,” concludes Anton Såmark-Roth.

Reference: “Spectroscopy along Flerovium Decay Chains: Discovery of ²⁸⁰Ds and an Excited State in ²⁸²Cn” by A. Såmark-Roth et al., 22 January 2021, Physical Review Letters.
DOI: 10.1103/PhysRevLett.126.032503