The NSCL accelerator has succeeded in obtaining record-breaking light magnesium nuclei containing only seven neutrons. Magnesium is the 12th element of the Periodic Table and one of the most abundant in the earth's crust. It is found in seawater and many minerals and plays an important role in the life of biological cells.

According to some assumptions, magnesium was one of the key elements that ensured the origin of life on our planet. And all this magnesium consists of a mixture of three relatively stable isotopes with masses of 24, 25 and 26 atomic units. They contain 12 protons and 12, 13 and 14 neutrons, respectively.

With the help of powerful accelerators and particle colliders, scientists have obtained other isotopes of magnesium, which are far from so stable: from magnesium-40, which has 28 neutrons in the nucleus, to magnesium-19 with only seven neutrons. And recently a new record was set: Yu Jin and his colleagues from the Peking and Michigan universities synthesized the lightest magnesium-18, which contains one more neutron less.

The work was done at the accelerator of the National Superconducting Cyclotron Laboratory (NSCL) at the University of Michigan. A beam of stable magnesium-24 nuclei accelerated to about half the speed of light and hit a beryllium target, scattering into a whole spectrum of lighter particles, including light magnesium isotopes. Among them was unstable magnesium-20 with a half-life of a fraction of a second.

The experiment was designed in such a way that the nuclei of magnesium-20, scattering, immediately hit the second target located 30 meters away. This made it possible to obtain an even lighter and more unstable magnesium-18, which exists literally in sextillion fractions of a second. It immediately decayed, converting directly on the target into oxygen-14, which is relatively stable (half-life - 71 seconds). The detectors registered the protons ejected during this decay, as well as oxygen-14 and traces of the intermediate isotope neon-16.

"Ultralight" magnesium-18 is extremely unstable and can appear only in some thermonuclear transformations taking place in the bowels of stars and other space "reactors". Its receipt and analysis in the laboratory will make it possible to better understand the processes occurring in them, which eventually fill the cosmos with all the variety of chemical elements and nuclei that make up the earth's crust and ourselves.

The article was published in the journal Physical Review Letters

PHOTO © S.M. Wang, Fudan University & Facility for Rare Isotope Beams, MSU
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