Researchers have discovered a new type of oxygen that may challenge nuclear physics' “magic numbers” theory.
Imagine looking inside an atom at its nucleus, which contains protons and neutrons. Elements are defined by their protons. Example: oxygen has eight protons. However, atoms can have varying neutron counts, creating isotopes.
Oxygen-28, with 20 neutrons, was recently discovered. Scientists synthesized oxygen-27 and oxygen-28 for the first time at the Radioactive Isotope Beam Factory (note: they do not mass produce and package beams).
Calcium-48 was fired at a beryllium ball initially. The lighter atoms had fewer protons and neutrons than the parent element. The scientists then isolated fluorine-29 from lighter atoms and hit it with liquid hydrogen to remove the proton needed to generate oxygen-28.
The scientists were surprised when oxygen-28 quickly disintegrated into another isotope, violating a nuclear physics premise about atom stability.
Elements and isotopes have “magic numbers”. An atom is stable when its protons or neutrons fill the nuclear shell. An atom with a magic number of protons and neutrons is called “doubly magic”. Oxygen-16, the most prevalent oxygen on Earth, is an example.
Oxygen-28 was supposed to be a doubly magic isotope because eight is a magic number for protons and 20 for neutrons. Instead, its instability prompted scientists to believe that the nuclear shell was not filled, casting doubt on whether 20 is a magic number. It may also explain why oxygen-28 was so hard to see.
Not only oxygen-28 loses its enchantment with 20 neutrons. The island of inversion occurs when neon, sodium, and magnesium isotopes with 20 neutrons lack nuclear shell closure.
The researchers suggested examining oxygen-28's nucleus in a higher-energy state for further research. This may clarify why 20 isn't magic.