Recently, researchers at Sweden's Chalmers University of Technology conducted nuclear fission reaction studies on 100 different types of exotic element atomic nuclei, such as platinum, mercury, and lead, aiming to better understand the nuclear fission process. The university's press release noted that this research not only aids in producing cleaner energy in the future but also reveals how elements are formed in the universe.
As countries around the world actively explore new ways to meet energy demands, nuclear fission technology is once again gaining attention. Although wind and solar power plants are being built at a rapid pace to achieve net-zero emissions goals, these technologies struggle to meet on-demand power needs and cannot operate around the clock. While nuclear fission technology can provide a carbon-free method to generate large amounts of energy, it also has issues such as producing substantial radioactive waste. Newer nuclear methods, such as small modular reactors or micro-reactors, aim to address these problems; however, understanding of the underlying fission reactions remains very limited, and researchers are working to fill this gap.
In the nuclear fission process, isotopes of heavy elements like uranium are bombarded by neutrons, causing their atomic nuclei to split into element fragments much smaller than the original isotopes, and these fragments are always asymmetrical, meaning they differ in atomic mass or size. Researchers attribute this to the shell structure of the atomic nucleus, where certain numbers of protons and neutrons are more stable than others. Since fission studies typically focus on specific isotopes for commercial purposes, understanding this process is challenging.
Andreas Heinz, Associate Professor of High Energy and Plasma Physics at Chalmers University of Technology, stated: "Fission is a process that people have studied for a long time, but only for a very limited number of isotopes." Typically, neutrons and the like are used to bombard the target isotope to observe fission, which poses no problem for long-lived isotopes like uranium, but is extremely difficult for atomic nuclei with much shorter lifespans.
Therefore, Heinz's team decided to study the atomic nuclei of 100 exotic elements, such as platinum, mercury, and lead, to gain a deeper understanding of the fission process. The studied atomic nuclei are marked in different colors, unlike the stable isotopes found in nature (marked in black), and the colors also indicate the manner in which fission occurs; the taller the bar, the greater the mass difference between the two fission fragments. The research group specifically chose elements with more protons than neutrons in the atomic nuclei.
Heinz added in the press release: "We are trying to figure out which shell effects cause the atomic nucleus to split into a light part and a heavy part, which is hard to predict and hard to measure experimentally. We measured the region of atomic nuclei that are undergoing fission, an area that has not been very thoroughly studied to date."
The research group was surprised to discover that the smaller fragments in the fission reaction are more stable due to a specific number of protons, namely 36. Heinz summarized: "The evidence from this study indicates that there is a shell effect in the number of protons in the light fission fragments, which is exactly why we have never seen this evolution before."
