The "overload" capability of atoms is much larger than people think. This is a relatively new research finding of a scientific group in the United States. Using particle accelerators, they created overweight aluminum and magnesium isotopes, in which the number of neutrons exceeds the number of protons. This achievement will help scientists find new theories for the combination of protons and neutrons into nuclei, and deepen their understanding of stellar elemental formation and decay. Related papers were published in the October 25 issue of Nature. The nucleus is formed by the strong interaction between protons and neutrons, and the number of protons determines the different elements. Elements with the same number of protons and different numbers of neutrons are isotopic to each other. The strength of the binding force between the two protons and the two neutrons is relatively weak (protons are mutually exclusive due to electrical repulsion) and the nucleus can be stably present mainly due to the role of proton-neutron pairs. Therefore, there is a theory that a condition for the existence of stable atoms is that the number of protons and neutrons in the nucleus cannot be too different. If this balance is broken, atoms will undergo radioactive decay or nuclear fission. Because of this, nuclear physicists have long been keen to find the boundary of such stability, known as the neutron drip line. Scientists have determined the neutron dripping lines of oxygen elements, but for some heavier elements, they have very short isotopes with neutrons, so it is very difficult to accurately measure neutron dripping lines. However, newer research has brought new insights. Thomas Baumann and colleagues at the National Superconducting Cyclometer Laboratory (NSCL) at Michigan State University in the United States have not only created overweight aluminum and magnesium isotopes with more neutrons, but they have also found that these isotopes are relatively stable for a certain period of time. The researchers fired a beam of accelerated high-energy calcium ions toward the tungsten layer, which produced new elements. Scientists have found in these new elements a very large number of aluminum and magnesium containing neutrons that decay in a matter of milliseconds. Further studies showed that the magnesium-40 isotope contains 28 neutrons, which is more than twice the normal number (12), and more than the scientists previously found that heavier magnesium isotopes containing 26 neutrons. Even more surprising to scientists, they also discovered overweight aluminum isotopes with 29 neutrons and 30 neutrons. According to current understanding, atoms with even numbers of neutrons are more stable, so the aluminum-42 isotopes with 29 neutrons cannot theoretically exist stably. Based on this discovery, the researchers predict that the aluminum neutron drip line may have been extended to 34, although this isotope has not yet been discovered. Bradley Sherrill, who participated in the study, said, "This study is a measure of the 'benchmark' of nuclear theory. It tests our understanding." In addition, the new findings are expected to deepen scientists’ understanding of neutron stars. Sherrill said that for neutron-rich nuclei, protons tend to be concentrated in the center, and the surface of the nuclei is almost completely covered by neutrons - and this happens to be the surface of the neutron star. Shaoxing Grace International Trade Co.,Ltd , https://www.shaoxinggrace.com
Nature: Studies have found that the number of neutrons in overweight aluminum and magnesium isotopes exceeds the number of protons