After decades of experiments, scientists finally observed oxygen28 at a research facility in Japan. The structure of this isotope behaved in a way that challenges theories about how atomic nuclei work.
Oxygen28 has the highest number of neutrons ever observed in the nucleus of an oxygen atom. This strange isotope consists of 20 neutrons and eight protons. The discovery was published last Wednesday (30) in the journal Nature.
Scientists observed the new form of oxygen at the RIKEN Radioactive Isotope Beam Facility as part of the work of an international team led by Tokyo Institute of Technology nuclear physicist Yosuke Kondo.
In addition to oxygen28, scientists were able to observe oxygen27, which has 19 neutrons. The two isotopes have eight protons in their nucleus because the atomic number of the element oxygen is eight. But until then, the largest number of neutrons observed in the oxygen nucleus was 18, and in oxygen26. The newly observed “oxygens” exceed this mark.
Produce “new oxygen”.
In the facility’s particle accelerator, scientists fired a beam of calcium48 isotopes at beryllium, creating fluorine29. The latter was then separated and collided with liquid hydrogen to release a proton and form oxygen28.
With this, the researchers created oxygen atoms27 and 28. However, the isotopes decayed into oxygen24, meaning they lost three and four neutrons, respectively. This was a surprise because the team expected oxygen28 to be stable. The idea came about because the isotope has eight protons and 20 neutrons and both eight and 20 are considered “magic numbers” in nuclear physics.
A “magic number” is the number of protons or neutrons that completely fill a shell of the atomic nucleus. In the case of oxygen28, it would be doubly “magic,” suggesting that it would be very stable.
But that’s not what the scientists observed: isotope 28 was actually unstable. This result challenges previous theoretical predictions, meaning “there are many more physicists who don’t know about the forces that hold atomic nuclei together,” according to a statement from the Tokyo Institute of Technology.
“The present results improve our understanding of nuclear structure and offer new insights, especially for extremely neutronrich nuclei,” says the institute, adding that the team hopes future research will solve many more mysteries about atomic nuclei.