They noticed a form of oxygen unknown until today

A team of researchers from the Tokyo Institute of Technology in Japan and Oak Ridge National Laboratory (ORNL) in the United States has discovered a new form of oxygen unknown today, called Oxygen -28, which contains the largest number of neutrons ever observed in the nuclear structure of this element. Moreover, their unstable properties contradict known theories about the behavior of these atomic structures.

The work, led by nuclear physicist Yusuke Kondo, led to the discovery of two previously unidentified isotopes of oxygen: oxygen-27 and oxygen-28, with 19 and 20 neutrons, respectively. However, Oxygen 28 particularly stands out in the “record-breaking” at The number of neutrons detected in the nucleus of an oxygen atom: Until today, oxygen-26 has taken the lead, with 18 neutrons.

Surprise and mystery

The researchers discovered that this new limit in the number of neutrons had been exceeded Unstable strange property of oxygen 28This goes in the opposite direction to the established theories about the structure of the atomic nucleus of these elements, according to A condition Published in ScienceAlert. The new study, which recently appeared in Nature, was made possible by experiments conducted at the Radioisotope Beam Fabrication (RIBF) at the RIKEN facility in Japan, and computer simulations at ORNL.

The scientists used the RIBF instrument, which is an accelerator Cyclotron It was designed to produce unstable isotopes, with the aim of generating various reactions and eventually achieving the observation of oxygen-27 and oxygen-28. The attempt was as successful as it was surprising: they estimated that both oxygen-27 and oxygen-28 are unstable and persist for only a short period of time. in a blink of an eye, It decays into oxygen-24 accompanied by 3 or 4 bulk neutrons, as appropriate in each case..

This is where the surprise about oxygen-28 begins in particular. According to one press release From ORNL, 20 neutrons and 8 protons interact in the atomic nucleus of oxygen-28, by Strong nuclear power, one of the four fundamental forces of nature. Specifically, the number following the name of an atom indicates the number of nucleons, that is, the total number of protons and neutrons combined in the atomic nucleus.

Physicists expected this combination of 8 protons and 20 neutrons in oxygen-28 It will generate stronger binding energy than other configurationsTo form stable and non-radioactive isotopes. On the contrary, they discovered that oxygen-28 is not stable at all It disintegrates quickly.

Oxygen 28 Wasn’t ‘Double Magic’

“We are learning How do atomic nuclei behave under extreme conditions?. Everything indicates that the traditional approach to the structure of atomic nuclei does not apply as we move towards the limits of the nuclear map. In this sense, new phenomena emerge and the small details of the strong nuclear force begin to play a major role in defining these limits.

We know that most Earth’s oxygenIncluding the air we breathe, it is Oxygen-16: to scientists, this combination is A “magic double” form of oxygen For its formation and stability. Oxygen-28 has long been expected to be the next “double magic” oxygen isotope after oxygen-16, but previous attempts to find it have been unsuccessful.

Now, Kondo and colleagues’ work has succeeded in monitoring oxygen-28, But with very different results than expected. In future research, specialists hope to solve the mystery about the composition of this form of oxygen and make new discoveries about the boundaries of the nuclear map.

reference

The first note of 28O. Y. Kondo et al. Nature (2023). doi:https://doi.org/10.1038/s41586-023-06352-6