A groundbreaking experiment on the splitting of heavy elements has revealed a never-before-seen ratio of the particles that make up atomic nuclei. Physicists led by Oleg Tarasov from the University of Michigan discovered new isotopes of the rare earth elements thulium, ytterbium and lutetium by cracking platinum nuclei. It’s a feat that scientists believe will help them understand the properties of neutron-rich nuclei and the processes that create new elements when neutron stars collide.

Researchers say the study also demonstrates the power of Michigan State University’s recently completed Rare Isotope Beam Facility (FRIB), which conducted its first experiment in June 2022. Not all element shapes are created equal. Each atomic nucleus consists of a set of subatomic particles known as nucleons (protons and neutrons). The number of protons is constant for all forms of an element and gives that element its atomic number.

However, the number of neutrons may vary. These variations determine the so-called isotopes of the element.

All elements have a number of isotopes that occur at different levels of stability. Some of them decay extremely quickly and break down into lighter elements under the influence of ionizing radiation. Some swing in perfect balance. Understanding different isotopes and how they behave helps scientists understand how the universe creates elements and predict the distribution of these elements in space and time.

To create their new isotope, Tarasov and his colleagues started with a platinum isotope with 120 neutrons called 198 Pt. Standard platinum has 117 neutrons; Using a heavier isotope could change the way the nucleus fragments.

They placed these atoms in FRIB, which uses a heavy ion accelerator to split atomic nuclei. Beams of rare isotopes are directed to the target at speeds exceeding half the speed of light. When they hit a target, these isotopes split into lighter isotopes of the nucleus; Physicists can then detect and study these isotopes.

During the disintegration of 198 Pt. Tarasov’s team discovered 182 Tm and 183 Tm with 113 and 114 neutrons, respectively; standard thulium has 69 neutrons. They also found 186 Yb and 187 Yb with 116 and 117 neutrons, respectively; standard ytterbium has 103 neutrons. They eventually found 190 Lu with 119 neutrons; standard lutetium has 104 neutrons.

Each of these isotopes was observed during several accelerator runs. The researchers say this means FRIB can be used to study the synthesis of neutron-enriched isotopes of heavy elements in regimes that have so far been largely neglected; not for lack of interest, but for the ability to create and detect them.

This could help us understand how violent cosmic events create the heaviest elements in the universe. Anything heavier than iron in the universe can only be created under extreme conditions, such as supernovae and collisions between neutron stars.

One of the nucleosynthesis processes observed in collisions of neutron stars is the fast neutron capture process, or r-process. This happens when the atomic nucleus begins to decay into a heavier element, rapidly covering the free-floating neutrons released during the kilonova explosion. This is how we obtain gold, strontium, platinum and other heavy metals.

They say the team’s experiment comes close to replicating the r-process. This means we may soon have a tool that can recreate one of the nucleosynthesis pathways seen in some of the most violent events the universe has to offer.

“FRIB’s unique capabilities, including very intense primary beams with energies exceeding those available at the National Superconducting Cyclotron Laboratory, make it an ideal facility for studying the region around neutron numbers of N = 126 and above,” the researchers wrote.

“Researchers at FRIB can use these reactions to produce, identify and study the properties of new isotopes, contributing to our understanding of nuclear physics, astrophysics and the fundamental properties of matter.”